├── .DS_Store ├── .gitignore ├── .idea ├── .gitignore ├── codeStyles │ ├── Project.xml │ └── codeStyleConfig.xml ├── jarRepositories.xml ├── learn-kotlin.iml ├── misc.xml └── vcs.xml ├── LICENSE ├── README.md ├── build.gradle ├── gradle.properties ├── gradle └── wrapper │ ├── gradle-wrapper.jar │ └── gradle-wrapper.properties ├── gradlew ├── gradlew.bat ├── settings.gradle └── src └── main └── kotlin ├── Animals.kt ├── Calculator.kt ├── ControlFlowAndTypeChecks.kt ├── DataClasses.kt ├── DataTypes.kt ├── Functions.kt ├── HelloWorld.kt ├── NullSafety.kt ├── Variables.kt ├── collections ├── Associate.kt ├── Filter.kt ├── Flatten.kt ├── Grouping.kt ├── Iterators.kt ├── Library.kt ├── Map.kt ├── Partition.kt ├── Reduce.kt ├── Sequence.kt ├── SortBy.kt └── Zip.kt └── scope ├── Also.kt ├── Apply.kt ├── Let.kt ├── Run.kt ├── ScopeFunctions.kt └── With.kt /.DS_Store: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/CodyEngel/learn-kotlin/073eee7125b9467c805747f7c0b806e54560814e/.DS_Store -------------------------------------------------------------------------------- /.gitignore: -------------------------------------------------------------------------------- 1 | # Compiled class file 2 | *.class 3 | 4 | # Log file 5 | *.log 6 | 7 | # BlueJ files 8 | *.ctxt 9 | 10 | # Mobile Tools for Java (J2ME) 11 | .mtj.tmp/ 12 | 13 | # Package Files # 14 | *.jar 15 | *.war 16 | *.nar 17 | *.ear 18 | *.zip 19 | *.tar.gz 20 | *.rar 21 | 22 | # virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml 23 | hs_err_pid* 24 | 25 | # IntelliJ 26 | /workspace.xml 27 | .idea/**/workspace.xml 28 | .idea/**/tasks.xml 29 | .idea/**/usage.statistics.xml 30 | .idea/**/dictionaries 31 | .idea/**/shelf 32 | .idea/**/contentModel.xml 33 | .idea/**/dataSources/ 34 | .idea/**/dataSources.ids 35 | .idea/**/dataSources.local.xml 36 | .idea/**/sqlDataSources.xml 37 | .idea/**/dynamic.xml 38 | .idea/**/uiDesigner.xml 39 | .idea/**/dbnavigator.xml 40 | .idea/**/gradle.xml 41 | .idea/**/libraries 42 | 43 | # Gradle 44 | .gradle 45 | /build/ 46 | gradle-app.setting 47 | !gradle-wrapper.jar -------------------------------------------------------------------------------- /.idea/.gitignore: -------------------------------------------------------------------------------- 1 | # Default ignored files 2 | /workspace.xml -------------------------------------------------------------------------------- /.idea/codeStyles/Project.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 6 | 7 | 9 | 10 | -------------------------------------------------------------------------------- /.idea/codeStyles/codeStyleConfig.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 5 | -------------------------------------------------------------------------------- /.idea/jarRepositories.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 9 | 10 | 14 | 15 | 19 | 20 | -------------------------------------------------------------------------------- /.idea/learn-kotlin.iml: -------------------------------------------------------------------------------- 1 | 2 | -------------------------------------------------------------------------------- /.idea/misc.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 7 | 8 | 9 | 10 | -------------------------------------------------------------------------------- /.idea/vcs.xml: -------------------------------------------------------------------------------- 1 | 2 | 3 | 4 | 5 | 6 | -------------------------------------------------------------------------------- /LICENSE: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. 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Such new versions will 567 | be similar in spirit to the present version, but may differ in detail to 568 | address new problems or concerns. 569 | 570 | Each version is given a distinguishing version number. If the 571 | Program specifies that a certain numbered version of the GNU General 572 | Public License "or any later version" applies to it, you have the 573 | option of following the terms and conditions either of that numbered 574 | version or of any later version published by the Free Software 575 | Foundation. If the Program does not specify a version number of the 576 | GNU General Public License, you may choose any version ever published 577 | by the Free Software Foundation. 578 | 579 | If the Program specifies that a proxy can decide which future 580 | versions of the GNU General Public License can be used, that proxy's 581 | public statement of acceptance of a version permanently authorizes you 582 | to choose that version for the Program. 583 | 584 | Later license versions may give you additional or different 585 | permissions. However, no additional obligations are imposed on any 586 | author or copyright holder as a result of your choosing to follow a 587 | later version. 588 | 589 | 15. Disclaimer of Warranty. 590 | 591 | THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY 592 | APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT 593 | HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY 594 | OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, 595 | THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 596 | PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM 597 | IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF 598 | ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 599 | 600 | 16. Limitation of Liability. 601 | 602 | IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING 603 | WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS 604 | THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY 605 | GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE 606 | USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF 607 | DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD 608 | PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), 609 | EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF 610 | SUCH DAMAGES. 611 | 612 | 17. Interpretation of Sections 15 and 16. 613 | 614 | If the disclaimer of warranty and limitation of liability provided 615 | above cannot be given local legal effect according to their terms, 616 | reviewing courts shall apply local law that most closely approximates 617 | an absolute waiver of all civil liability in connection with the 618 | Program, unless a warranty or assumption of liability accompanies a 619 | copy of the Program in return for a fee. 620 | 621 | END OF TERMS AND CONDITIONS 622 | 623 | How to Apply These Terms to Your New Programs 624 | 625 | If you develop a new program, and you want it to be of the greatest 626 | possible use to the public, the best way to achieve this is to make it 627 | free software which everyone can redistribute and change under these terms. 628 | 629 | To do so, attach the following notices to the program. It is safest 630 | to attach them to the start of each source file to most effectively 631 | state the exclusion of warranty; and each file should have at least 632 | the "copyright" line and a pointer to where the full notice is found. 633 | 634 | 635 | Copyright (C) 636 | 637 | This program is free software: you can redistribute it and/or modify 638 | it under the terms of the GNU General Public License as published by 639 | the Free Software Foundation, either version 3 of the License, or 640 | (at your option) any later version. 641 | 642 | This program is distributed in the hope that it will be useful, 643 | but WITHOUT ANY WARRANTY; without even the implied warranty of 644 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 645 | GNU General Public License for more details. 646 | 647 | You should have received a copy of the GNU General Public License 648 | along with this program. If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | Copyright (C) 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . 675 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # learn-kotlin 2 | This is a repository that provides the code used during my "Learn Kotlin" video series. 3 | -------------------------------------------------------------------------------- /build.gradle: -------------------------------------------------------------------------------- 1 | plugins { 2 | id 'java' 3 | id 'org.jetbrains.kotlin.jvm' version '1.3.41' 4 | } 5 | 6 | group 'dev.engel' 7 | version '1.0-SNAPSHOT' 8 | 9 | sourceCompatibility = 1.8 10 | 11 | repositories { 12 | mavenCentral() 13 | } 14 | 15 | dependencies { 16 | implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8" 17 | testCompile group: 'junit', name: 'junit', version: '4.12' 18 | } 19 | 20 | compileKotlin { 21 | kotlinOptions.jvmTarget = "1.8" 22 | } 23 | compileTestKotlin { 24 | kotlinOptions.jvmTarget = "1.8" 25 | } -------------------------------------------------------------------------------- /gradle.properties: -------------------------------------------------------------------------------- 1 | kotlin.code.style=official -------------------------------------------------------------------------------- /gradle/wrapper/gradle-wrapper.jar: -------------------------------------------------------------------------------- https://raw.githubusercontent.com/CodyEngel/learn-kotlin/073eee7125b9467c805747f7c0b806e54560814e/gradle/wrapper/gradle-wrapper.jar -------------------------------------------------------------------------------- /gradle/wrapper/gradle-wrapper.properties: -------------------------------------------------------------------------------- 1 | distributionBase=GRADLE_USER_HOME 2 | distributionPath=wrapper/dists 3 | distributionUrl=https\://services.gradle.org/distributions/gradle-5.2.1-bin.zip 4 | zipStoreBase=GRADLE_USER_HOME 5 | zipStorePath=wrapper/dists 6 | -------------------------------------------------------------------------------- /gradlew: -------------------------------------------------------------------------------- 1 | #!/usr/bin/env sh 2 | 3 | ############################################################################## 4 | ## 5 | ## Gradle start up script for UN*X 6 | ## 7 | ############################################################################## 8 | 9 | # Attempt to set APP_HOME 10 | # Resolve links: $0 may be a link 11 | PRG="$0" 12 | # Need this for relative symlinks. 13 | while [ -h "$PRG" ] ; do 14 | ls=`ls -ld "$PRG"` 15 | link=`expr "$ls" : '.*-> \(.*\)$'` 16 | if expr "$link" : '/.*' > /dev/null; then 17 | PRG="$link" 18 | else 19 | PRG=`dirname "$PRG"`"/$link" 20 | fi 21 | done 22 | SAVED="`pwd`" 23 | cd "`dirname \"$PRG\"`/" >/dev/null 24 | APP_HOME="`pwd -P`" 25 | cd "$SAVED" >/dev/null 26 | 27 | APP_NAME="Gradle" 28 | APP_BASE_NAME=`basename "$0"` 29 | 30 | # Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. 31 | DEFAULT_JVM_OPTS='"-Xmx64m"' 32 | 33 | # Use the maximum available, or set MAX_FD != -1 to use that value. 34 | MAX_FD="maximum" 35 | 36 | warn () { 37 | echo "$*" 38 | } 39 | 40 | die () { 41 | echo 42 | echo "$*" 43 | echo 44 | exit 1 45 | } 46 | 47 | # OS specific support (must be 'true' or 'false'). 48 | cygwin=false 49 | msys=false 50 | darwin=false 51 | nonstop=false 52 | case "`uname`" in 53 | CYGWIN* ) 54 | cygwin=true 55 | ;; 56 | Darwin* ) 57 | darwin=true 58 | ;; 59 | MINGW* ) 60 | msys=true 61 | ;; 62 | NONSTOP* ) 63 | nonstop=true 64 | ;; 65 | esac 66 | 67 | CLASSPATH=$APP_HOME/gradle/wrapper/gradle-wrapper.jar 68 | 69 | # Determine the Java command to use to start the JVM. 70 | if [ -n "$JAVA_HOME" ] ; then 71 | if [ -x "$JAVA_HOME/jre/sh/java" ] ; then 72 | # IBM's JDK on AIX uses strange locations for the executables 73 | JAVACMD="$JAVA_HOME/jre/sh/java" 74 | else 75 | JAVACMD="$JAVA_HOME/bin/java" 76 | fi 77 | if [ ! -x "$JAVACMD" ] ; then 78 | die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME 79 | 80 | Please set the JAVA_HOME variable in your environment to match the 81 | location of your Java installation." 82 | fi 83 | else 84 | JAVACMD="java" 85 | which java >/dev/null 2>&1 || die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 86 | 87 | Please set the JAVA_HOME variable in your environment to match the 88 | location of your Java installation." 89 | fi 90 | 91 | # Increase the maximum file descriptors if we can. 92 | if [ "$cygwin" = "false" -a "$darwin" = "false" -a "$nonstop" = "false" ] ; then 93 | MAX_FD_LIMIT=`ulimit -H -n` 94 | if [ $? -eq 0 ] ; then 95 | if [ "$MAX_FD" = "maximum" -o "$MAX_FD" = "max" ] ; then 96 | MAX_FD="$MAX_FD_LIMIT" 97 | fi 98 | ulimit -n $MAX_FD 99 | if [ $? -ne 0 ] ; then 100 | warn "Could not set maximum file descriptor limit: $MAX_FD" 101 | fi 102 | else 103 | warn "Could not query maximum file descriptor limit: $MAX_FD_LIMIT" 104 | fi 105 | fi 106 | 107 | # For Darwin, add options to specify how the application appears in the dock 108 | if $darwin; then 109 | GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\"" 110 | fi 111 | 112 | # For Cygwin, switch paths to Windows format before running java 113 | if $cygwin ; then 114 | APP_HOME=`cygpath --path --mixed "$APP_HOME"` 115 | CLASSPATH=`cygpath --path --mixed "$CLASSPATH"` 116 | JAVACMD=`cygpath --unix "$JAVACMD"` 117 | 118 | # We build the pattern for arguments to be converted via cygpath 119 | ROOTDIRSRAW=`find -L / -maxdepth 1 -mindepth 1 -type d 2>/dev/null` 120 | SEP="" 121 | for dir in $ROOTDIRSRAW ; do 122 | ROOTDIRS="$ROOTDIRS$SEP$dir" 123 | SEP="|" 124 | done 125 | OURCYGPATTERN="(^($ROOTDIRS))" 126 | # Add a user-defined pattern to the cygpath arguments 127 | if [ "$GRADLE_CYGPATTERN" != "" ] ; then 128 | OURCYGPATTERN="$OURCYGPATTERN|($GRADLE_CYGPATTERN)" 129 | fi 130 | # Now convert the arguments - kludge to limit ourselves to /bin/sh 131 | i=0 132 | for arg in "$@" ; do 133 | CHECK=`echo "$arg"|egrep -c "$OURCYGPATTERN" -` 134 | CHECK2=`echo "$arg"|egrep -c "^-"` ### Determine if an option 135 | 136 | if [ $CHECK -ne 0 ] && [ $CHECK2 -eq 0 ] ; then ### Added a condition 137 | eval `echo args$i`=`cygpath --path --ignore --mixed "$arg"` 138 | else 139 | eval `echo args$i`="\"$arg\"" 140 | fi 141 | i=$((i+1)) 142 | done 143 | case $i in 144 | (0) set -- ;; 145 | (1) set -- "$args0" ;; 146 | (2) set -- "$args0" "$args1" ;; 147 | (3) set -- "$args0" "$args1" "$args2" ;; 148 | (4) set -- "$args0" "$args1" "$args2" "$args3" ;; 149 | (5) set -- "$args0" "$args1" "$args2" "$args3" "$args4" ;; 150 | (6) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" ;; 151 | (7) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" ;; 152 | (8) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" ;; 153 | (9) set -- "$args0" "$args1" "$args2" "$args3" "$args4" "$args5" "$args6" "$args7" "$args8" ;; 154 | esac 155 | fi 156 | 157 | # Escape application args 158 | save () { 159 | for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done 160 | echo " " 161 | } 162 | APP_ARGS=$(save "$@") 163 | 164 | # Collect all arguments for the java command, following the shell quoting and substitution rules 165 | eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS" 166 | 167 | # by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong 168 | if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then 169 | cd "$(dirname "$0")" 170 | fi 171 | 172 | exec "$JAVACMD" "$@" 173 | -------------------------------------------------------------------------------- /gradlew.bat: -------------------------------------------------------------------------------- 1 | @if "%DEBUG%" == "" @echo off 2 | @rem ########################################################################## 3 | @rem 4 | @rem Gradle startup script for Windows 5 | @rem 6 | @rem ########################################################################## 7 | 8 | @rem Set local scope for the variables with windows NT shell 9 | if "%OS%"=="Windows_NT" setlocal 10 | 11 | set DIRNAME=%~dp0 12 | if "%DIRNAME%" == "" set DIRNAME=. 13 | set APP_BASE_NAME=%~n0 14 | set APP_HOME=%DIRNAME% 15 | 16 | @rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. 17 | set DEFAULT_JVM_OPTS="-Xmx64m" 18 | 19 | @rem Find java.exe 20 | if defined JAVA_HOME goto findJavaFromJavaHome 21 | 22 | set JAVA_EXE=java.exe 23 | %JAVA_EXE% -version >NUL 2>&1 24 | if "%ERRORLEVEL%" == "0" goto init 25 | 26 | echo. 27 | echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 28 | echo. 29 | echo Please set the JAVA_HOME variable in your environment to match the 30 | echo location of your Java installation. 31 | 32 | goto fail 33 | 34 | :findJavaFromJavaHome 35 | set JAVA_HOME=%JAVA_HOME:"=% 36 | set JAVA_EXE=%JAVA_HOME%/bin/java.exe 37 | 38 | if exist "%JAVA_EXE%" goto init 39 | 40 | echo. 41 | echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 42 | echo. 43 | echo Please set the JAVA_HOME variable in your environment to match the 44 | echo location of your Java installation. 45 | 46 | goto fail 47 | 48 | :init 49 | @rem Get command-line arguments, handling Windows variants 50 | 51 | if not "%OS%" == "Windows_NT" goto win9xME_args 52 | 53 | :win9xME_args 54 | @rem Slurp the command line arguments. 55 | set CMD_LINE_ARGS= 56 | set _SKIP=2 57 | 58 | :win9xME_args_slurp 59 | if "x%~1" == "x" goto execute 60 | 61 | set CMD_LINE_ARGS=%* 62 | 63 | :execute 64 | @rem Setup the command line 65 | 66 | set CLASSPATH=%APP_HOME%\gradle\wrapper\gradle-wrapper.jar 67 | 68 | @rem Execute Gradle 69 | "%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -classpath "%CLASSPATH%" org.gradle.wrapper.GradleWrapperMain %CMD_LINE_ARGS% 70 | 71 | :end 72 | @rem End local scope for the variables with windows NT shell 73 | if "%ERRORLEVEL%"=="0" goto mainEnd 74 | 75 | :fail 76 | rem Set variable GRADLE_EXIT_CONSOLE if you need the _script_ return code instead of 77 | rem the _cmd.exe /c_ return code! 78 | if not "" == "%GRADLE_EXIT_CONSOLE%" exit 1 79 | exit /b 1 80 | 81 | :mainEnd 82 | if "%OS%"=="Windows_NT" endlocal 83 | 84 | :omega 85 | -------------------------------------------------------------------------------- /settings.gradle: -------------------------------------------------------------------------------- 1 | rootProject.name = 'learn-kotlin' 2 | 3 | -------------------------------------------------------------------------------- /src/main/kotlin/Animals.kt: -------------------------------------------------------------------------------- 1 | fun main() { 2 | val doggo = Dog() 3 | printXtraLn("Talk To Me: ${doggo.talk()}") 4 | printXtraLn("Run Doggo Run: ${doggo.move()}") 5 | printXtraLn("Did You Enjoy Your Steak? ${doggo.eat("steak")}") 6 | printXtraLn("Did You Enjoy Your Carrot? ${doggo.eat("carrot")}") 7 | 8 | val kitty = Cat() 9 | printXtraLn("Talk To Me: ${kitty.talk()}") 10 | printXtraLn("Run Kitty Run: ${kitty.move()}") 11 | printXtraLn("Did You Enjoy Your Steak? ${kitty.eat("steak")}") 12 | printXtraLn("Did You Enjoy Your Fish? ${kitty.eat("fish")}") 13 | 14 | 15 | } 16 | 17 | interface Animal {} 18 | 19 | typealias Movement = String 20 | typealias Talk = String 21 | typealias Food = String 22 | typealias DidEnjoy = Boolean 23 | 24 | interface CanMove { 25 | fun move(): Movement 26 | } 27 | 28 | interface CanTalk { 29 | fun talk(): Talk 30 | } 31 | 32 | interface CanEat { 33 | fun eat(food: Food): DidEnjoy 34 | } 35 | 36 | class FastMover : CanMove { 37 | override fun move(): Movement { 38 | return "FAST" 39 | } 40 | } 41 | 42 | class Slither : CanMove { 43 | override fun move(): Movement { 44 | return "SLITHER" 45 | } 46 | } 47 | 48 | class Herbivoure : CanEat { 49 | override fun eat(food: String): DidEnjoy { 50 | return food == "veggie" 51 | } 52 | 53 | } 54 | 55 | class Carnivoure : CanEat { 56 | override fun eat(food: String): DidEnjoy { 57 | return food == "fish" || food == "steak" 58 | } 59 | } 60 | 61 | class GardenSnake : CanEat by Herbivoure(), CanMove by Slither() 62 | class Python : CanEat by Carnivoure(), CanMove by Slither() 63 | 64 | class Cat : CanMove by FastMover(), CanTalk, CanEat by Carnivoure() { 65 | override fun talk(): Talk { 66 | return "MEOW!" 67 | } 68 | } 69 | 70 | class Dog : CanMove by FastMover(), CanTalk, CanEat by Carnivoure() { 71 | override fun talk(): Talk { 72 | return "WOOF!" 73 | } 74 | } 75 | -------------------------------------------------------------------------------- /src/main/kotlin/Calculator.kt: -------------------------------------------------------------------------------- 1 | import kotlin.random.Random 2 | 3 | fun main() { 4 | printXtraLn("Properties & Fields / Calculator") 5 | val calculator = CalculatorStore.theBestCalculator 6 | calculator.add(2) 7 | calculator.add(2) 8 | calculator.subtract(3) 9 | // calculator.multiply(4) 10 | calculator.add(1) 11 | printXtraLn("Result: ${calculator.currentValue}") 12 | 13 | val subtractionCalculator = CalculatorStore.subtractionCalculator 14 | 15 | } 16 | 17 | object CalculatorStore { 18 | val theBestCalculator: Calculator = BetterCalculator(42) 19 | val aRandomCalculator: Calculator = RandomCalculator() 20 | 21 | val subtractionCalculator: SubtractionCalculator = BetterCalculator() 22 | 23 | const val ZERO = 0 24 | const val LARGE_NEGATIVE = Int.MIN_VALUE 25 | const val LARGE_POSITIVE = Int.MAX_VALUE 26 | } 27 | 28 | class RandomCalculator : Calculator( 29 | initialValue = Random.nextInt(Int.MIN_VALUE, Int.MAX_VALUE) 30 | ) 31 | 32 | class BadCalculator : Calculator() { 33 | override var currentValue: Int = super.currentValue 34 | get() { 35 | return field - 1 36 | } 37 | set(value) { 38 | field = value * value 39 | } 40 | 41 | } 42 | 43 | class BetterCalculator(initialValue: Int = 0) : Calculator(initialValue) { 44 | fun remainder(number: Int): Int { 45 | println("$currentValue % $number") 46 | return currentValue % number 47 | } 48 | 49 | companion object { 50 | val negativeCalculator = BetterCalculator(-10) 51 | 52 | fun clone(calculator: Calculator): Calculator { 53 | return BetterCalculator(calculator.currentValue) 54 | } 55 | 56 | fun empty(): Calculator { 57 | return BetterCalculator() 58 | } 59 | 60 | fun fix(calculator: BadCalculator): BetterCalculator { 61 | return clone(calculator) as BetterCalculator 62 | } 63 | } 64 | } 65 | 66 | interface AdditionCalculator { 67 | fun add(previousNumber: Int, number: Int): Int 68 | 69 | class Real : AdditionCalculator { 70 | override fun add(previousNumber: Int, number: Int): Int { 71 | println("$previousNumber + $number") 72 | return previousNumber + number 73 | } 74 | } 75 | } 76 | 77 | interface SubtractionCalculator { 78 | fun subtract(previousNumber: Int, number: Int): Int 79 | 80 | class Real : SubtractionCalculator { 81 | override fun subtract(previousNumber: Int, number: Int): Int { 82 | println("$previousNumber - $number") 83 | return previousNumber - number 84 | } 85 | } 86 | } 87 | 88 | interface MultiplicationCalculator { 89 | fun multiply(number: Int): Int 90 | } 91 | 92 | abstract class Calculator( 93 | initialValue: Int = 0 94 | ) : AdditionCalculator by AdditionCalculator.Real(), SubtractionCalculator by SubtractionCalculator.Real() { 95 | open var currentValue = initialValue 96 | protected set 97 | 98 | fun add(number: Int): Int { 99 | currentValue = add(currentValue, number) 100 | return currentValue 101 | } 102 | 103 | fun subtract(number: Int): Int { 104 | currentValue = subtract(currentValue, number) 105 | return currentValue 106 | } 107 | 108 | // fun add(number: Int): Int { 109 | // println("$currentValue + $number") 110 | // currentValue += number 111 | // return currentValue 112 | // } 113 | // 114 | // fun subtract(number: Int): Int { 115 | // println("$currentValue - $number") 116 | // currentValue -= number 117 | // return currentValue 118 | // } 119 | // 120 | // fun multiply(number: Int): Int { 121 | // println("$currentValue * $number") 122 | // currentValue *= number 123 | // return currentValue 124 | // } 125 | 126 | fun divide(number: Int): Int { 127 | println("$currentValue / $number") 128 | currentValue /= number 129 | return currentValue 130 | } 131 | } -------------------------------------------------------------------------------- /src/main/kotlin/ControlFlowAndTypeChecks.kt: -------------------------------------------------------------------------------- 1 | import kotlin.math.max 2 | 3 | fun main() { 4 | println("Control Flow & Type Checks") 5 | 6 | println("Basic & traditional way...") 7 | val a = 1 8 | val b = 2 9 | // if (a < b) maxNumber = b 10 | // var maxNumber: Int 11 | // if (a > b) { 12 | // maxNumber = a 13 | // } else { 14 | // maxNumber = b 15 | // } 16 | 17 | val maxNumber = if (a > b) { 18 | println("It looks like a will be our max number :)") 19 | a 20 | } else { 21 | println("It looks like b will be our max number :(") 22 | b 23 | } 24 | 25 | println("The maxNumber is $maxNumber") 26 | 27 | println("When expressions...") 28 | 29 | val x: Any = 1 30 | when (x) { 31 | 1 -> println("x == 1") 32 | 2 -> println("x == 2") 33 | else -> println("x is something else") 34 | } 35 | 36 | println("Multiple Options") 37 | when (x) { 38 | 0, 1 -> println("x is 0 or 1") 39 | else -> println("x is something else") 40 | } 41 | 42 | println("Ranges") 43 | when (x) { 44 | in 1..10 -> println("x is in the range") 45 | in listOf(2, 4, 6, 8, 10, 12, 14, 16, 18, 20) -> println("x is at least a valid number...") 46 | !in 10..20 -> println("x is wayyyyyyyy outside of the range") 47 | else -> println("x is none of the above, somehow") 48 | } 49 | 50 | println("Casting & Smart Casting") 51 | when (x) { 52 | is String -> println("Length of x: ${x.length}") 53 | is Int -> println("Value of x: $x") 54 | else -> println("X is something else") 55 | } 56 | 57 | println("Replacing if/elseif/else with when") 58 | var y = 2 59 | // if (y % 2 != 0) { 60 | // println("y is odd") 61 | // } else if (y % 2 == 0) { 62 | // println("y is even") 63 | // } else { 64 | // println("y is funky") 65 | // } 66 | when { 67 | y % 2 != 0 -> println("y is odd") 68 | y % 2 == 0 -> println("y is even") 69 | else -> println("y is funky") 70 | } 71 | 72 | println("For Loops") 73 | for (i in 1..3) { 74 | println(i) 75 | } 76 | 77 | println("Fancier For Loops...") 78 | for (i in 6 downTo 0 step 2) { 79 | println(i) 80 | } 81 | 82 | println("For Loops With Collections") 83 | val myCollection = listOf("Hey", "Be", "Sure", "To", "Like", "&", "Subscribe", "😊") 84 | 85 | for (item in myCollection) println(item) 86 | 87 | println("For Loops With Collections on Indices") 88 | for (i in myCollection.indices) { 89 | println("$i : ${myCollection[i]}") 90 | } 91 | 92 | println("For Loops With Collections for Items & Indices") 93 | for ((index, value) in myCollection.withIndex()) { 94 | println("$index : $value") 95 | } 96 | 97 | println("While Loops") 98 | var number = 12 99 | while (number > 0) { 100 | number-- 101 | println("We're still going to decrement the number...") 102 | } 103 | 104 | do { 105 | val anotherNumber = 0 106 | println("Do While...") 107 | } while (anotherNumber > 0) 108 | 109 | println("Break...") 110 | number = 12 111 | while (number > 0) { 112 | number -- 113 | if (number % 5 == 0) break 114 | println("We're still going to decrement the number...") 115 | } 116 | 117 | println("Continue...") 118 | number = 12 119 | while (number > 0) { 120 | number-- 121 | if (number % 2 == 0) continue 122 | println("We're still going to decrement the number...") 123 | } 124 | } -------------------------------------------------------------------------------- /src/main/kotlin/DataClasses.kt: -------------------------------------------------------------------------------- 1 | data class Person( 2 | val name: String = "Jane Doe", 3 | val age: Int = 22, 4 | val gender: String = "Female", 5 | val nationality: List = listOf("United States") 6 | ) 7 | 8 | fun main() { 9 | printXtraLn("Data Classes") 10 | val cody = Person( 11 | age = 29, 12 | nationality = listOf("United States"), 13 | gender = "Male", 14 | name = "Cody Engel" 15 | ) 16 | 17 | printXtraLn("Cody: $cody") 18 | 19 | val newCody = cody.copy(nationality = listOf("United States", "Canada")) 20 | 21 | printXtraLn("New Cody: $newCody") 22 | 23 | val (name, age) = newCody 24 | 25 | printXtraLn("Name: $name, Age: $age") 26 | 27 | val defaultPerson = Person( 28 | gender = "Male", 29 | age = 75, 30 | name = "John Smith" 31 | ) 32 | printXtraLn("Default Person: $defaultPerson") 33 | } -------------------------------------------------------------------------------- /src/main/kotlin/DataTypes.kt: -------------------------------------------------------------------------------- 1 | fun main() { 2 | // Numbers - Min/Max Values 3 | println(Byte.MIN_VALUE) 4 | println(Byte.MAX_VALUE) 5 | println() 6 | println(Short.MIN_VALUE) 7 | println(Short.MAX_VALUE) 8 | println() 9 | println(Int.MIN_VALUE) 10 | println(Int.MAX_VALUE) 11 | println() 12 | println(Long.MIN_VALUE) 13 | println(Long.MAX_VALUE) 14 | println() 15 | println(Float.MIN_VALUE) 16 | println(Float.MAX_VALUE) 17 | println() 18 | println(Double.MIN_VALUE) 19 | println(Double.MAX_VALUE) 20 | println() 21 | 22 | // Different Ways to Represent 1 23 | println(1L) 24 | println(1) 25 | println(0x01) 26 | println(0b01) 27 | println(1.0) 28 | println() 29 | 30 | // Numeric Conversations 31 | println(1.toLong()) 32 | println(1.toByte()) 33 | println(1.toShort()) 34 | println(1.toDouble().toFloat().toLong().toByte().toShort()) 35 | println() 36 | 37 | // Math 38 | println(2 + 2) 39 | println(7 / 3) 40 | println(7 / 3.toFloat()) 41 | println(7 / 3.toDouble()) 42 | println(7 * 2 + 1 / 16 - 32) 43 | println() 44 | 45 | // Binary Operations 46 | println(4 shr 2) // 0b100 -> 0b001 47 | println(1 shl 1) // 0b01 -> 0b10 48 | println(8 and 2) 49 | println(8 or 2) 50 | println(8 xor 2) 51 | println() 52 | 53 | // Underscores to make numbers more readable 54 | println(1000000) 55 | println(1_000_000) 56 | println(1234_5678_9012_3456L) 57 | println(0xFFECDE5E) 58 | println(0xFF_EC_DE_5E) 59 | println(0b11010010_01101001_10010100_10010010) 60 | println() 61 | 62 | // Characters 63 | println('a') 64 | println(97.toChar()) 65 | println("EMOJI REDEMPTION") 66 | "😅".toCharArray().forEach { println(it.toInt()) } 67 | println('\u1F60') 68 | println('\t') 69 | print('b') 70 | print('\n') 71 | print('c') 72 | println() 73 | println() 74 | 75 | // Strings 76 | println("abcd") 77 | println("🤷‍♂️") 78 | println("abcd\nefgh\tijkl") 79 | println(""" 80 | abcd 81 | efgh ijkl 82 | """.trimIndent()) 83 | println("Int: ${2 + 3}") 84 | println() 85 | 86 | // Booleans 87 | println(true) 88 | println(false) 89 | println(true || false) 90 | println(true && false) 91 | println(!true) 92 | println(!false) 93 | 94 | // Arrays 95 | println(Array(5) { it * it }) // [0, 1, 2, 3, 4] 96 | Array(5) { it * it }.forEach { println(it) } 97 | println() 98 | println(intArrayOf(0, 1, 2, 3, 4)) 99 | intArrayOf(0, 1, 2, 3, 4).forEach { println(it) } 100 | println() 101 | longArrayOf(0, 1, 2, 3, 4) 102 | doubleArrayOf(0.3, 0.5, 1.0, 232.3423) 103 | floatArrayOf(3.4.toFloat(), 0.23.toFloat(), Double.MAX_VALUE.toFloat()) 104 | .forEach { println(it) } 105 | } -------------------------------------------------------------------------------- /src/main/kotlin/Functions.kt: -------------------------------------------------------------------------------- 1 | fun doSomeMath(x: Int = 2, y: Int = 2, operator: String = "add"): Int { 2 | return when (operator) { 3 | "add" -> x + y 4 | "subtract" -> x - y 5 | "multiply" -> x * y 6 | "divide" -> x / y 7 | else -> 0 8 | } 9 | } 10 | 11 | fun printXtraLn(message: Any) { 12 | println(message) 13 | println() 14 | } 15 | 16 | fun main() { 17 | printXtraLn("Kotlin Functions") 18 | printXtraLn(doSomeMath(8, 5, "subtract")) 19 | printXtraLn(doSomeMath(x = 3, operator = "multiply", y = 4)) 20 | } -------------------------------------------------------------------------------- /src/main/kotlin/HelloWorld.kt: -------------------------------------------------------------------------------- 1 | fun main() { 2 | println("Hello World!") 3 | } -------------------------------------------------------------------------------- /src/main/kotlin/NullSafety.kt: -------------------------------------------------------------------------------- 1 | fun main() { 2 | // Let's Talk About Null 3 | var thisCouldExist: String? = "Sometimes this exists, sometimes it does not." 4 | println(thisCouldExist) 5 | 6 | // thisCouldExist = null 7 | // println(thisCouldExist) 8 | // println(thisCouldExist!!.length) 9 | // thisCouldExist = null 10 | 11 | if (thisCouldExist != null) { 12 | println(thisCouldExist.length) 13 | } 14 | 15 | thisCouldExist?.let { 16 | println(it.length) 17 | } 18 | 19 | println(thisCouldExist?.length ?: 0) 20 | } -------------------------------------------------------------------------------- /src/main/kotlin/Variables.kt: -------------------------------------------------------------------------------- 1 | fun main() { 2 | // Variables in Kotlin 3 | val okayEmojiPleaseWork = "😭" // immutable 4 | println(okayEmojiPleaseWork) 5 | 6 | var changingEmoji = "😭" 7 | println(changingEmoji) 8 | changingEmoji = "😂" 9 | println(changingEmoji) 10 | 11 | // More common use case... 12 | var counter = 0 13 | println(counter++) 14 | println(counter++) 15 | println(counter++) 16 | } -------------------------------------------------------------------------------- /src/main/kotlin/collections/Associate.kt: -------------------------------------------------------------------------------- 1 | package collections 2 | 3 | fun main() { 4 | Library.books.associate { 5 | // println("Associate Book: $it") 6 | Pair(it.genres.first(), it) // Pair 7 | }.forEach { key, value -> 8 | // println("$key : $value") 9 | } 10 | 11 | Library.books.associateBy { it.genres.first() }.forEach { key, value -> 12 | // println("$key : $value") 13 | } 14 | 15 | Library.books.associateWith { it.genres.first() }.forEach { key, value -> 16 | // println("$key : $value") 17 | } 18 | 19 | val theType: Map = Library.books.associateBy { it.genres.first() } 20 | } -------------------------------------------------------------------------------- /src/main/kotlin/collections/Filter.kt: -------------------------------------------------------------------------------- 1 | package collections 2 | 3 | fun main() { 4 | val multipleAuthors = Library.books 5 | .filter { book: Book -> 6 | book.authors.size > 1 7 | } 8 | // .map { "${it.title} by ${it.authors.joinToString { it.name }}" } 9 | // .also { it.forEach { println(it) } } 10 | 11 | val nonFiction = Library.books 12 | .filter { book -> 13 | book.genres.any { genre -> 14 | genre is Genre.NonFiction 15 | } 16 | } 17 | // .map { "${it.title} is ${it.genres}" } 18 | // .also { it.forEach { println(it) } } 19 | 20 | val notFiction = Library.books 21 | .filter { book -> 22 | book.genres.none { genre -> 23 | genre is Genre.Fiction 24 | } 25 | } 26 | // .map { "${it.title} is ${it.genres}" } 27 | // .also { it.forEach { println(it) } } 28 | 29 | val allFiction = Library.books 30 | .filter { book -> 31 | book.genres.all { genre -> 32 | genre is Genre.Fiction 33 | } 34 | } 35 | // .map { "${it.title} is ${it.genres}" } 36 | // .also { it.forEach { println(it) } } 37 | 38 | val allFictionNotJK = allFiction.filterNot { book -> 39 | book.authors.any { it.name == "J.K. Rowling" } 40 | } 41 | .map { "${it.title} is ${it.genres}" } 42 | .also { it.forEach { println(it) } } 43 | } -------------------------------------------------------------------------------- /src/main/kotlin/collections/Flatten.kt: -------------------------------------------------------------------------------- 1 | package collections 2 | 3 | fun main() { 4 | val listOfAListOfAuthors: List> = Library.books.map { it.authors } 5 | // .also { it.forEach { println(it) } } 6 | 7 | val authors: List = listOfAListOfAuthors.flatten() 8 | // .also { it.forEach { println(it) } } 9 | 10 | val flatMappedAuthors: List = listOfAListOfAuthors 11 | .flatMap { authorList -> 12 | // val flattenedAuthorNames = mutableListOf() 13 | // authorList.forEach { author -> 14 | // flattenedAuthorNames.add(author.name) 15 | // } 16 | // flattenedAuthorNames 17 | authorList.map { it.name } 18 | }.also { it.forEach { println(it) } } 19 | } -------------------------------------------------------------------------------- /src/main/kotlin/collections/Grouping.kt: -------------------------------------------------------------------------------- 1 | package collections 2 | 3 | fun main() { 4 | Library.books.groupBy { book -> 5 | book.genres 6 | } 7 | // .forEach { key, value -> 8 | // println("=== $key ===") 9 | // value.forEachIndexed { index, book -> 10 | // println("${index + 1}. ${book.title}") 11 | // } 12 | // } 13 | 14 | Library.books.map { book -> 15 | book.genres.map { genre -> 16 | Pair(genre, book) 17 | } 18 | }.flatten().groupBy { genreBooks -> 19 | genreBooks.first 20 | }.forEach { entry -> 21 | println("=== ${entry.key} ===") 22 | entry.value.forEachIndexed { index, pair -> 23 | println("${index + 1}. ${pair.second.title}") 24 | } 25 | } 26 | } -------------------------------------------------------------------------------- /src/main/kotlin/collections/Iterators.kt: -------------------------------------------------------------------------------- 1 | package collections 2 | 3 | fun main() { 4 | Library.books.iterator().let { iterator -> 5 | while (iterator.hasNext()) { 6 | val book = iterator.next() 7 | // println(book) 8 | } 9 | } 10 | 11 | Library.books.let { books: List -> 12 | for (book in books) { 13 | // println(book) 14 | } 15 | } 16 | 17 | Library.books.forEach { book -> 18 | // println(book) 19 | } 20 | 21 | Library.books.forEachIndexed { index, book -> 22 | println("${index + 1} - $book") 23 | } 24 | } -------------------------------------------------------------------------------- /src/main/kotlin/collections/Library.kt: -------------------------------------------------------------------------------- 1 | package collections 2 | 3 | object Library { 4 | val books: List = listOf( 5 | Book( 6 | title = "Zero to One", 7 | authors = listOf(Author("Peter Thiel"), Author("Blake Masters")), 8 | genre = Genre.NonFiction.Business, 9 | price = 1963 10 | ), 11 | Book( 12 | title = "Why We Sleep: Unlocking the Power of Sleep and Dreams", 13 | author = Author("Matthew Walker"), 14 | genre = Genre.NonFiction.SelfHelp, 15 | price = 1796 16 | ), 17 | Book( 18 | title = "Utopia for Realists: How We Can Build the Ideal World", 19 | author = Author("Rutger Bregman"), 20 | genre = Genre.NonFiction.Politics, 21 | price = 899 22 | ), 23 | Book( 24 | title = "Friend of a Friend: Understanding the Hidden Networks That Can Transform Your Life and Your Career", 25 | author = Author("David Burkus"), 26 | genre = Genre.NonFiction.Business, 27 | price = 1469 28 | ), 29 | Book( 30 | title = "The Moment of Lift: How Empowering Women Changes the World", 31 | author = Author("Melinda Gates"), 32 | genre = Genre.NonFiction.Feminism, 33 | price = 1449 34 | ), 35 | Book( 36 | title = "Profit First: Transform Your Business from a Cash-Eating Monster to a Money-Making Machine", 37 | author = Author("Mike Michalowicz"), 38 | genre = Genre.NonFiction.Business, 39 | price = 1916 40 | ), 41 | Book( 42 | title = "The Dip: A Little Book That Teaches You When to Quit (and When to Stick)", 43 | author = Author("Seth Godin"), 44 | genres = listOf(Genre.NonFiction.Business, Genre.NonFiction.SelfHelp), 45 | price = 949 46 | ), 47 | Book( 48 | title = "The Making of a Manager: What to Do When Everyone Looks to You", 49 | author = Author("Julie Zhuo"), 50 | genres = listOf(Genre.NonFiction.Business, Genre.NonFiction.SelfHelp), 51 | price = 1529 52 | ), 53 | Book( 54 | title = "The Transparency Sale: How Unexpected Honesty and Understanding the Buying Brain Can Transform Your Results", 55 | author = Author("Todd Caponi"), 56 | genre = Genre.NonFiction.Business, 57 | price = 1549 58 | ), 59 | Book( 60 | title = "Company of One: Why Staying Small Is the Next Big Thing for Business", 61 | author = Author("Paul Jarvis"), 62 | genres = listOf(Genre.NonFiction.Business, Genre.NonFiction.SelfHelp), 63 | price = 1159 64 | ), 65 | Book( 66 | title = "It Doesn't Have to Be Crazy at Work", 67 | authors = listOf(Author("Jason Fried"), Author("David Heinemeier Hansson")), 68 | genres = listOf(Genre.NonFiction.Business, Genre.NonFiction.SelfHelp), 69 | price = 1639 70 | ), 71 | Book( 72 | title = "How Democracies Die", 73 | authors = listOf(Author("Steven Levitsky"), Author("Daniel Ziblatt")), 74 | genre = Genre.NonFiction.Politics, 75 | price = 1175 76 | ), 77 | Book( 78 | title = "ReWork", 79 | authors = listOf(Author("Jason Fried"), Author("David Heinemeier Hansson")), 80 | genres = listOf(Genre.NonFiction.Business, Genre.NonFiction.SelfHelp), 81 | price = 1499 82 | ), 83 | Book( 84 | title = "High Output Management", 85 | author = Author("Andrew Grove"), 86 | genre = Genre.NonFiction.Business, 87 | price = 899 88 | ), 89 | Book( 90 | title = "Solving the Procrastination Puzzle: A Concise Guide to Strategies for Change", 91 | author = Author("Timothy Pychyl"), 92 | genre = Genre.NonFiction.SelfHelp, 93 | price = 999 94 | ), 95 | Book( 96 | title = "Blitzscaling: The Lightning-Fast Path to Building Massively Valuable Companies", 97 | authors = listOf(Author("Reid Hoffman"), Author("Chris Yeh")), 98 | genre = Genre.NonFiction.Business, 99 | price = 1829 100 | ), 101 | Book( 102 | title = "Capital Gaines: Smart Things I Learned Doing Stupid Stuff", 103 | author = Author("Chip Gaines"), 104 | genres = listOf(Genre.NonFiction.Biography, Genre.NonFiction.Business), 105 | price = 1681 106 | ), 107 | Book( 108 | title = "Digital Minimalism: Choosing a Focused Life in a Noisy World", 109 | author = Author("Cal Newport"), 110 | genre = Genre.NonFiction.SelfHelp, 111 | price = 1599 112 | ), 113 | Book( 114 | title = "Leaders Eat Last: Why Some Teams Pull Together and Others Don't", 115 | author = Author("Simon Sinek"), 116 | genres = listOf(Genre.NonFiction.Business, Genre.NonFiction.SelfHelp), 117 | price = 989 118 | ), 119 | Book( 120 | title = "The Compound Effect", 121 | author = Author("Darren Hardy"), 122 | genres = listOf(Genre.NonFiction.Business, Genre.NonFiction.SelfHelp), 123 | price = 1249 124 | ), 125 | Book( 126 | title = "Start with Why: How Great Leaders Inspire Everyone to Take Action", 127 | author = Author("Simon Sinek"), 128 | genres = listOf(Genre.NonFiction.Business, Genre.NonFiction.SelfHelp), 129 | price = 879 130 | ), 131 | Book( 132 | title = "The Hard Thing About Hard Things: Building a Business When There Are No Easy Answers", 133 | author = Author("Ben Horowitz"), 134 | genres = listOf(Genre.NonFiction.Business, Genre.NonFiction.SelfHelp), 135 | price = 2111 136 | ), 137 | Book( 138 | title = "Hooked: How to Build Habit-Forming Products", 139 | author = Author("Nir Eyal"), 140 | genre = Genre.NonFiction.Business, 141 | price = 1847 142 | ), 143 | Book( 144 | title = "Make Your Bed: Little Things That Can Change Your Life...And Maybe the World", 145 | author = Author("William McRaven"), 146 | genres = listOf(Genre.NonFiction.Business, Genre.NonFiction.SelfHelp), 147 | price = 1148 148 | ), 149 | Book( 150 | title = "How Google Works", 151 | authors = listOf(Author("Eric Schmidt"), Author("Jonathan Rosenberg ")), 152 | genre = Genre.NonFiction.Business, 153 | price = 1399 154 | ), 155 | Book( 156 | title = "Artemis", 157 | author = Author("Andy Weir"), 158 | genre = Genre.Fiction.ScienceFiction, 159 | price = 1059 160 | ), 161 | Book( 162 | title = "The Martian", 163 | author = Author("Andy Weir"), 164 | genre = Genre.Fiction.ScienceFiction, 165 | price = 969 166 | ), 167 | Book( 168 | title = "The Ballad of Songbirds and Snakes", 169 | author = Author("Suzanne Collins"), 170 | genres = listOf(Genre.Fiction.Fantasy, Genre.Fiction.ScienceFiction), 171 | price = 1737 172 | ), 173 | Book( 174 | title = "The Hunger Games", 175 | author = Author("Suzanne Collins"), 176 | genres = listOf(Genre.Fiction.Fantasy, Genre.Fiction.ScienceFiction), 177 | price = 877 178 | ), 179 | Book( 180 | title = "Catching Fire", 181 | author = Author("Suzanne Collins"), 182 | genres = listOf(Genre.Fiction.Fantasy, Genre.Fiction.ScienceFiction), 183 | price = 991 184 | ), 185 | Book( 186 | title = "Mockingjay", 187 | author = Author("Suzanne Collins"), 188 | genres = listOf(Genre.Fiction.Fantasy, Genre.Fiction.ScienceFiction), 189 | price = 1017 190 | ), 191 | Book( 192 | title = "Lord of the Flies", 193 | author = Author("William Golding"), 194 | genre = Genre.Fiction.Classics, 195 | price = 599 196 | ), 197 | Book( 198 | title = "Harry Potter and the Sorcerer's Stone", 199 | author = Author("J.K. Rowling"), 200 | genre = Genre.Fiction.Fantasy, 201 | price = 3419 202 | ), 203 | Book( 204 | title = "Harry Potter and the Chamber of Secrets", 205 | author = Author("J.K. Rowling"), 206 | genre = Genre.Fiction.Fantasy, 207 | price = 2057 208 | ), 209 | Book( 210 | title = "Harry Potter and the Prisoner of Azkaban", 211 | author = Author("J.K. Rowling"), 212 | genre = Genre.Fiction.Fantasy, 213 | price = 2069 214 | ), 215 | Book( 216 | title = "Harry Potter and the Goblet of Fire", 217 | author = Author("J.K. Rowling"), 218 | genre = Genre.Fiction.Fantasy, 219 | price = 3498 220 | ), 221 | Book( 222 | title = "Harry Potter and the Order of the Phoenix", 223 | author = Author("J.K. Rowling"), 224 | genre = Genre.Fiction.Fantasy, 225 | price = 4505 226 | ), 227 | Book( 228 | title = "Harry Potter and the Half-Blood Prince", 229 | author = Author("J.K. Rowling"), 230 | genre = Genre.Fiction.Fantasy, 231 | price = 1999 232 | ), 233 | Book( 234 | title = "Harry Potter and the Deathly Hallows", 235 | author = Author("J.K. Rowling"), 236 | genre = Genre.Fiction.Fantasy, 237 | price = 1374 238 | ) 239 | ) 240 | } 241 | 242 | data class Book(val title: String, val authors: List, val genres: List, val price: Int) { 243 | constructor(title: String, author: Author, genre: Genre, price: Int) : this(title, listOf(author), listOf(genre), price) 244 | constructor(title: String, authors: List, genre: Genre, price: Int) : this (title, authors, listOf(genre), price) 245 | constructor(title: String, author: Author, genres: List, price: Int) : this(title, listOf(author), genres, price) 246 | } 247 | 248 | data class Author(val name: String) 249 | 250 | sealed class Genre { 251 | 252 | sealed class Fiction : Genre() { 253 | object Classics : Fiction() 254 | object Fantasy : Fiction() 255 | object ScienceFiction : Fiction() 256 | } 257 | 258 | sealed class NonFiction : Genre() { 259 | object Biography : NonFiction() 260 | object Business : NonFiction() 261 | object Feminism : NonFiction() 262 | object Politics : NonFiction() 263 | object SelfHelp : NonFiction() 264 | } 265 | 266 | override fun toString(): String { 267 | return this::javaClass.get().simpleName 268 | } 269 | } -------------------------------------------------------------------------------- /src/main/kotlin/collections/Map.kt: -------------------------------------------------------------------------------- 1 | package collections 2 | 3 | fun main() { 4 | 5 | // Print All Authors 6 | val justAuthors = Library.books 7 | .map { book: Book -> 8 | book.authors 9 | } 10 | .map { authors: List -> 11 | authors.joinToString { it.name } 12 | } 13 | .joinToString(separator = "\n") 14 | 15 | // println("=== Authors ===") 16 | // println(justAuthors) 17 | 18 | // Print Book Title + Authors 19 | val titleAndAuthors = Library.books 20 | .map { book: Book -> 21 | val authors = book.authors.joinToString { it.name } 22 | "${book.title} by $authors" 23 | }.joinToString(separator = "\n") 24 | 25 | // println("=== Title & Authors ===") 26 | // println(titleAndAuthors) 27 | 28 | // Book Title + Location/ID 29 | println("=== Books with Index") 30 | val booksWithIndex = Library.books 31 | .mapIndexed { index, book -> "$index - ${book.title}" } 32 | 33 | println(booksWithIndex.joinToString(separator = "\n")) 34 | } -------------------------------------------------------------------------------- /src/main/kotlin/collections/Partition.kt: -------------------------------------------------------------------------------- 1 | package collections 2 | 3 | fun main() { 4 | val fictionNonFiction: Pair, List> = 5 | Library.books.partition { book -> 6 | book.genres.all { genre -> 7 | genre is Genre.NonFiction 8 | } 9 | } 10 | 11 | println("=== Non Fiction ===") 12 | fictionNonFiction.first.forEach { println(it) } 13 | 14 | println("=== Fiction ===") 15 | fictionNonFiction.second.forEach { println(it) } 16 | } -------------------------------------------------------------------------------- /src/main/kotlin/collections/Reduce.kt: -------------------------------------------------------------------------------- 1 | package collections 2 | 3 | import kotlin.math.roundToInt 4 | 5 | fun main() { 6 | Library.books.map { it.price } 7 | .reduce { accumulator: Int, price: Int -> accumulator + price } 8 | // .also { println("Total Value: $it") } 9 | 10 | Library.books.map { it.price }.sum() 11 | // .also { println("Total Value: $it") } 12 | 13 | Library.books.sumBy { it.price }//.also { println("Total Value: $it") } 14 | 15 | Library.books.map { it.price } 16 | .average().roundToInt() 17 | .also { println("Average Value: $it") } 18 | 19 | Library.books.minBy { it.price } 20 | .also { println("Cheapest Book: $it") } 21 | 22 | Library.books.maxBy { it.price } 23 | .also { println("Most Expensive Book: $it") } 24 | } -------------------------------------------------------------------------------- /src/main/kotlin/collections/Sequence.kt: -------------------------------------------------------------------------------- 1 | package collections 2 | 3 | import kotlin.system.measureTimeMillis 4 | 5 | fun main() { 6 | 7 | (0 until 10).map { 8 | measureTimeMillis { 9 | testingSequence() 10 | } 11 | }.sum().also { executionTime -> println("Exeucted in ${executionTime}ms") } 12 | 13 | } 14 | 15 | fun testingSequence() { 16 | // Library.books 17 | // .asSequence() 18 | (0 until 100_000) 19 | .map { 20 | Book( 21 | title = it.toString(), 22 | author = Author(it.toString()), 23 | genre = Genre.NonFiction.SelfHelp, 24 | price = it * 100 25 | ) 26 | } 27 | .asSequence() 28 | .map { book -> 29 | book.copy(title = book.title.toUpperCase()) 30 | } 31 | .map { book -> 32 | val firstAuthor = book.authors.first() 33 | book.copy(authors = listOf(firstAuthor)) 34 | } 35 | .filter { book -> 36 | book.genres.all { it is Genre.NonFiction } 37 | } 38 | .filter { book -> 39 | book.price >= 1000 40 | } 41 | .map { book -> 42 | book.title 43 | } 44 | //.forEach { bookTitle -> println(bookTitle) } 45 | } -------------------------------------------------------------------------------- /src/main/kotlin/collections/SortBy.kt: -------------------------------------------------------------------------------- 1 | package collections 2 | 3 | fun main() { 4 | listOf(10, 4, 3, 1, 57, 80, 0, -12).sorted() 5 | // .also { println(it) } 6 | 7 | // Library.books.sorted() 8 | Library.books.sortedBy { book -> 9 | book.title 10 | }//.forEach { println(it.title) } 11 | 12 | Library.books.sortedByDescending { book -> 13 | book.title 14 | }//.forEach { println(it.title) } 15 | 16 | Library.books.reversed()//.forEach { println(it.title) } 17 | 18 | Library.books.sortedBy { it.title } 19 | .shuffled() 20 | // .forEach { println(it.title) } 21 | 22 | val aToZBooks = Library.books.sortedBy { it.title } 23 | val shuffledBooks = aToZBooks.shuffled() 24 | // .forEach { println(it.title) } 25 | } -------------------------------------------------------------------------------- /src/main/kotlin/collections/Zip.kt: -------------------------------------------------------------------------------- 1 | package collections 2 | 3 | fun main() { 4 | 5 | val authors: List> = Library.books.map { it.authors } 6 | val genres: List> = Library.books.map { it.genres } 7 | 8 | val authorGenres: List, List>> = authors.zip(genres) 9 | // authorGenres.forEach { println("${it.first} : ${it.second}") } 10 | 11 | authorGenres.unzip() 12 | .also { 13 | println(it.first) 14 | println(it.second) 15 | } 16 | } -------------------------------------------------------------------------------- /src/main/kotlin/scope/Also.kt: -------------------------------------------------------------------------------- 1 | package scope 2 | 3 | fun main() { 4 | val homer = FictionalPerson( 5 | firstName = "Homer", 6 | lastName = "Simpson", 7 | age = 39, 8 | address = Address( 9 | number = 742, 10 | street = "Evergreen Terrace", 11 | city = "Springfield", 12 | state = "Oregon", 13 | zipCode = 97475 14 | ) 15 | ).also { insert(it) } 16 | 17 | println(homer) 18 | } 19 | 20 | fun insert(fictionalPerson: FictionalPerson) { 21 | println("Inserted $fictionalPerson into the database.") 22 | } -------------------------------------------------------------------------------- /src/main/kotlin/scope/Apply.kt: -------------------------------------------------------------------------------- 1 | package scope 2 | 3 | fun main() { 4 | val homer = FictionalPerson( 5 | firstName = "Homer", 6 | lastName = "Simpson", 7 | age = 39, 8 | address = Address( 9 | number = 742, 10 | street = "Evergreen Terrace", 11 | city = "Springfield", 12 | state = "Oregon", 13 | zipCode = 97475 14 | ) 15 | ) 16 | 17 | println(homer) 18 | 19 | val returned = homer.apply { 20 | address.state = "Illinois" 21 | address.zipCode = 62629 22 | println("Homer Has Moved To Illinois") 23 | gender = "Male" 24 | hasFacebook = true 25 | hasTwitter = false 26 | occupation = "Nuclear Safety Inspector" 27 | println("Optional Values Have Been Applied") 28 | } 29 | 30 | println(homer) 31 | println(returned) 32 | } -------------------------------------------------------------------------------- /src/main/kotlin/scope/Let.kt: -------------------------------------------------------------------------------- 1 | package scope 2 | 3 | data class FictionalPerson( 4 | var firstName: String, 5 | var lastName: String, 6 | var age: Int, 7 | var address: Address, 8 | var gender: String? = null, 9 | var hasFacebook: Boolean = false, 10 | var hasTwitter: Boolean = false, 11 | var occupation: String? = null 12 | ) 13 | data class Address( 14 | var number: Int, 15 | var street: String, 16 | var city: String, 17 | var state: String, 18 | var zipCode: Int 19 | ) 20 | 21 | fun main() { 22 | val homer = FictionalPerson( 23 | firstName = "Homer", 24 | lastName = "Simpson", 25 | age = 39, 26 | address = Address( 27 | number = 742, 28 | street = "Evergreen Terrace", 29 | city = "Springfield", 30 | state = "Oregon", 31 | zipCode = 97475 32 | ) 33 | ) 34 | 35 | println(homer) 36 | 37 | val returned = homer.address.let { address -> 38 | address.state = "Illinois" 39 | address.zipCode = 62629 40 | } 41 | 42 | println(homer) 43 | println(returned) 44 | 45 | var marge: FictionalPerson? = FictionalPerson( 46 | firstName = "Marge", 47 | lastName = "Simpson", 48 | age = 36, 49 | address = Address( 50 | number = 742, 51 | street = "Evergreen Terrace", 52 | city = "Springfield", 53 | state = "Oregon", 54 | zipCode = 97475 55 | ) 56 | ) 57 | 58 | println(marge) 59 | marge = null 60 | 61 | marge?.let { person -> 62 | person.address = homer.address 63 | person.gender = "Female" 64 | person.hasFacebook = true 65 | person.hasTwitter = false 66 | } ?: println("Whoops, marge is actually null, isn't that bad?") 67 | 68 | println(marge) 69 | } -------------------------------------------------------------------------------- /src/main/kotlin/scope/Run.kt: -------------------------------------------------------------------------------- 1 | package scope 2 | 3 | fun main() { 4 | val homer = FictionalPerson( 5 | firstName = "Homer", 6 | lastName = "Simpson", 7 | age = 39, 8 | address = Address( 9 | number = 742, 10 | street = "Evergreen Terrace", 11 | city = "Springfield", 12 | state = "Oregon", 13 | zipCode = 97475 14 | ) 15 | ) 16 | 17 | println(homer) 18 | 19 | val returned = homer.address.run { 20 | state = "Illinois" 21 | zipCode = 62629 22 | } 23 | 24 | println(homer) 25 | println(returned) 26 | 27 | var marge: FictionalPerson? = FictionalPerson( 28 | firstName = "Marge", 29 | lastName = "Simpson", 30 | age = 36, 31 | address = Address( 32 | number = 742, 33 | street = "Evergreen Terrace", 34 | city = "Springfield", 35 | state = "Oregon", 36 | zipCode = 97475 37 | ) 38 | ) 39 | 40 | println(marge) 41 | marge = null 42 | 43 | marge?.run { 44 | address = homer.address 45 | hasTwitter = true 46 | gender = "Female" 47 | occupation = "Housewife" 48 | } ?: println("Whoops, marge was null.") 49 | 50 | println(marge) 51 | } -------------------------------------------------------------------------------- /src/main/kotlin/scope/ScopeFunctions.kt: -------------------------------------------------------------------------------- 1 | package scope 2 | 3 | fun main() { 4 | println("Scope Functions") 5 | println() 6 | val scopeFunctions = "Hello scope functions!" 7 | 8 | val let = scopeFunctions.let { 9 | println("What is let?") 10 | it.replace(" ", ".").reversed() 11 | } 12 | println(let) 13 | println() 14 | 15 | val run = scopeFunctions.run { 16 | println("What is run?") 17 | toUpperCase().removePrefix("HELLO").trim() 18 | } 19 | println(run) 20 | println() 21 | 22 | val with = with(scopeFunctions) { 23 | println("What is with?") 24 | drop(5).toByteArray().contentToString() 25 | } 26 | println(with) 27 | println() 28 | 29 | val apply = mutableListOf().apply { 30 | println("What is apply?") 31 | add(1) 32 | add(2) 33 | add(3) 34 | } 35 | println(apply.toString()) 36 | println() 37 | 38 | val also = mutableListOf().also { 39 | it.add(1) 40 | it.add(2) 41 | println("This is a side effect thing.") 42 | } 43 | println(also.toString()) 44 | println() 45 | } -------------------------------------------------------------------------------- /src/main/kotlin/scope/With.kt: -------------------------------------------------------------------------------- 1 | package scope 2 | 3 | fun main() { 4 | val homer = FictionalPerson( 5 | firstName = "Homer", 6 | lastName = "Simpson", 7 | age = 39, 8 | address = Address( 9 | number = 742, 10 | street = "Evergreen Terrace", 11 | city = "Springfield", 12 | state = "Oregon", 13 | zipCode = 97475 14 | ) 15 | ) 16 | 17 | println(homer) 18 | 19 | moveToIllinois(homer) 20 | 21 | println(homer) 22 | 23 | var marge: FictionalPerson? = FictionalPerson( 24 | firstName = "Marge", 25 | lastName = "Simpson", 26 | age = 36, 27 | address = Address( 28 | number = 742, 29 | street = "Evergreen Terrace", 30 | city = "Springfield", 31 | state = "Oregon", 32 | zipCode = 97475 33 | ) 34 | ) 35 | 36 | moveToIllinois(marge!!) 37 | 38 | println(marge) 39 | } 40 | 41 | fun moveToIllinois(fictionalPerson: FictionalPerson) = with(fictionalPerson.address) { 42 | state = "Illinois" 43 | zipCode = 62629 44 | } --------------------------------------------------------------------------------