├── .gitignore
├── Readme.md
├── poi-generated-file.xlsx
├── pom.xml
├── sample-xls-file.xls
├── sample-xlsx-file.xlsx
└── src
    └── main
        └── java
            ├── ExcelReader.java
            └── ExcelWriter.java


/.gitignore:
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1 | .DS_Store
2 | .idea
3 | *.class
4 | target
5 | *.iml
6 | 


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/Readme.md:
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1 | ## Learn how to Read and Write Excel files in Java using Apache POI
2 | 
3 | [How to Read Excel files in Java using Apache POI](https://www.callicoder.com/java-read-excel-file-apache-poi/)
4 | 
5 | [How to Write to an Excel file in Java using Apache POI](https://www.callicoder.com/java-write-excel-file-apache-poi/)


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/poi-generated-file.xlsx:
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https://raw.githubusercontent.com/callicoder/java-read-write-excel-file-using-apache-poi/c68f5375bb860a02c9b8368c134fd89c56db30f9/poi-generated-file.xlsx


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/pom.xml:
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 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | <project xmlns="http://maven.apache.org/POM/4.0.0"
 3 |          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4 |          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5 |     <modelVersion>4.0.0</modelVersion>
 6 | 
 7 |     <groupId>com.callicoder</groupId>
 8 |     <artifactId>excel-utils</artifactId>
 9 |     <version>1.0-SNAPSHOT</version>
10 | 
11 |     <properties>
12 |         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
13 |         <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
14 |         <java.version>1.8</java.version>
15 |     </properties>
16 | 
17 |     <dependencies>
18 |         <!-- https://mvnrepository.com/artifact/org.apache.poi/poi -->
19 |         <dependency>
20 |             <groupId>org.apache.poi</groupId>
21 |             <artifactId>poi</artifactId>
22 |             <version>3.17</version>
23 |         </dependency>
24 | 
25 |         <!-- https://mvnrepository.com/artifact/org.apache.poi/poi-ooxml -->
26 |         <dependency>
27 |             <groupId>org.apache.poi</groupId>
28 |             <artifactId>poi-ooxml</artifactId>
29 |             <version>3.17</version>
30 |         </dependency>
31 |     </dependencies>
32 | 
33 |     <build>
34 |         <plugins>
35 |             <plugin>
36 |                 <groupId>org.apache.maven.plugins</groupId>
37 |                 <artifactId>maven-compiler-plugin</artifactId>
38 |                 <version>3.7.0</version>
39 |                 <configuration>
40 |                     <source>${java.version}</source>
41 |                     <target>${java.version}</target>
42 |                 </configuration>
43 |             </plugin>
44 |             <!--
45 |             <plugin>
46 |                 <groupId>org.apache.maven.plugins</groupId>
47 |                 <artifactId>maven-shade-plugin</artifactId>
48 |                 <version>3.1.0</version>
49 |                 <configuration>
50 |                     <transformers>
51 |                     <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
52 |                         <mainClass>ExcelReader</mainClass>
53 |                     </transformer>
54 |                     </transformers>
55 |                 </configuration>
56 |                 <executions>
57 |                   <execution>
58 |                     <phase>package</phase>
59 |                     <goals>
60 |                       <goal>shade</goal>
61 |                     </goals>
62 |                   </execution>
63 |                 </executions>
64 |             </plugin>
65 |             -->
66 |         </plugins>
67 |     </build>
68 | </project>


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/sample-xls-file.xls:
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https://raw.githubusercontent.com/callicoder/java-read-write-excel-file-using-apache-poi/c68f5375bb860a02c9b8368c134fd89c56db30f9/sample-xls-file.xls


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/sample-xlsx-file.xlsx:
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https://raw.githubusercontent.com/callicoder/java-read-write-excel-file-using-apache-poi/c68f5375bb860a02c9b8368c134fd89c56db30f9/sample-xlsx-file.xlsx


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/src/main/java/ExcelReader.java:
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  1 | import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
  2 | import org.apache.poi.ss.usermodel.*;
  3 | 
  4 | import java.io.File;
  5 | import java.io.IOException;
  6 | import java.util.Iterator;
  7 | 
  8 | /**
  9 |  * Created by rajeevkumarsingh on 18/12/17.
 10 |  */
 11 | 
 12 | public class ExcelReader {
 13 |     public static final String SAMPLE_XLS_FILE_PATH = "./sample-xls-file.xls";
 14 |     public static final String SAMPLE_XLSX_FILE_PATH = "./sample-xlsx-file.xlsx";
 15 | 
 16 |     public static void main(String[] args) throws IOException, InvalidFormatException {
 17 | 
 18 |         // Creating a Workbook from an Excel file (.xls or .xlsx)
 19 |         Workbook workbook = WorkbookFactory.create(new File(SAMPLE_XLSX_FILE_PATH));
 20 | 
 21 |         // Retrieving the number of sheets in the Workbook
 22 |         System.out.println("Workbook has " + workbook.getNumberOfSheets() + " Sheets : ");
 23 | 
 24 |         /*
 25 |            =============================================================
 26 |            Iterating over all the sheets in the workbook (Multiple ways)
 27 |            =============================================================
 28 |         */
 29 | 
 30 |         // 1. You can obtain a sheetIterator and iterate over it
 31 |         Iterator<Sheet> sheetIterator = workbook.sheetIterator();
 32 |         System.out.println("Retrieving Sheets using Iterator");
 33 |         while (sheetIterator.hasNext()) {
 34 |             Sheet sheet = sheetIterator.next();
 35 |             System.out.println("=> " + sheet.getSheetName());
 36 |         }
 37 | 
 38 |         // 2. Or you can use a for-each loop
 39 |         System.out.println("Retrieving Sheets using for-each loop");
 40 |         for(Sheet sheet: workbook) {
 41 |             System.out.println("=> " + sheet.getSheetName());
 42 |         }
 43 | 
 44 |         // 3. Or you can use a Java 8 forEach wih lambda
 45 |         System.out.println("Retrieving Sheets using Java 8 forEach with lambda");
 46 |         workbook.forEach(sheet -> {
 47 |             System.out.println("=> " + sheet.getSheetName());
 48 |         });
 49 | 
 50 |         /*
 51 |            ==================================================================
 52 |            Iterating over all the rows and columns in a Sheet (Multiple ways)
 53 |            ==================================================================
 54 |         */
 55 | 
 56 |         // Getting the Sheet at index zero
 57 |         Sheet sheet = workbook.getSheetAt(0);
 58 | 
 59 |         // Create a DataFormatter to format and get each cell's value as String
 60 |         DataFormatter dataFormatter = new DataFormatter();
 61 | 
 62 |         // 1. You can obtain a rowIterator and columnIterator and iterate over them
 63 |         System.out.println("\n\nIterating over Rows and Columns using Iterator\n");
 64 |         Iterator<Row> rowIterator = sheet.rowIterator();
 65 |         while (rowIterator.hasNext()) {
 66 |             Row row = rowIterator.next();
 67 | 
 68 |             // Now let's iterate over the columns of the current row
 69 |             Iterator<Cell> cellIterator = row.cellIterator();
 70 | 
 71 |             while (cellIterator.hasNext()) {
 72 |                 Cell cell = cellIterator.next();
 73 |                 String cellValue = dataFormatter.formatCellValue(cell);
 74 |                 System.out.print(cellValue + "\t");
 75 |             }
 76 |             System.out.println();
 77 |         }
 78 | 
 79 |         // 2. Or you can use a for-each loop to iterate over the rows and columns
 80 |         System.out.println("\n\nIterating over Rows and Columns using for-each loop\n");
 81 |         for (Row row: sheet) {
 82 |             for(Cell cell: row) {
 83 |                 String cellValue = dataFormatter.formatCellValue(cell);
 84 |                 System.out.print(cellValue + "\t");
 85 |             }
 86 |             System.out.println();
 87 |         }
 88 | 
 89 |         // 3. Or you can use Java 8 forEach loop with lambda
 90 |         System.out.println("\n\nIterating over Rows and Columns using Java 8 forEach with lambda\n");
 91 |         sheet.forEach(row -> {
 92 |             row.forEach(cell -> {
 93 |                 printCellValue(cell);
 94 |             });
 95 |             System.out.println();
 96 |         });
 97 | 
 98 |         // Closing the workbook
 99 |         workbook.close();
100 |     }
101 | 
102 |     private static void printCellValue(Cell cell) {
103 |         switch (cell.getCellTypeEnum()) {
104 |             case BOOLEAN:
105 |                 System.out.print(cell.getBooleanCellValue());
106 |                 break;
107 |             case STRING:
108 |                 System.out.print(cell.getRichStringCellValue().getString());
109 |                 break;
110 |             case NUMERIC:
111 |                 if (DateUtil.isCellDateFormatted(cell)) {
112 |                     System.out.print(cell.getDateCellValue());
113 |                 } else {
114 |                     System.out.print(cell.getNumericCellValue());
115 |                 }
116 |                 break;
117 |             case FORMULA:
118 |                 System.out.print(cell.getCellFormula());
119 |                 break;
120 |             case BLANK:
121 |                 System.out.print("");
122 |                 break;
123 |             default:
124 |                 System.out.print("");
125 |         }
126 | 
127 |         System.out.print("\t");
128 |     }
129 | }
130 | 


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/src/main/java/ExcelWriter.java:
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  1 | import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
  2 | import org.apache.poi.ss.usermodel.*;
  3 | import org.apache.poi.xssf.usermodel.XSSFWorkbook;
  4 | 
  5 | import java.io.File;
  6 | import java.io.FileOutputStream;
  7 | import java.io.IOException;
  8 | import java.util.ArrayList;
  9 | import java.util.Calendar;
 10 | import java.util.Date;
 11 | import java.util.List;
 12 | 
 13 | /**
 14 |  * Created by rajeevkumarsingh on 22/12/17.
 15 |  */
 16 | 
 17 | public class ExcelWriter {
 18 | 
 19 |     private static String[] columns = {"Name", "Email", "Date Of Birth", "Salary"};
 20 | 
 21 |     private static List<Employee> employees =  new ArrayList<>();
 22 | 
 23 |     static {
 24 |         Calendar dateOfBirth = Calendar.getInstance();
 25 |         dateOfBirth.set(1992, 7, 21);
 26 |         employees.add(new Employee("Rajeev Singh", "rajeev@example.com",
 27 |                 dateOfBirth.getTime(), 1200000.0));
 28 | 
 29 |         dateOfBirth.set(1965, 10, 15);
 30 |         employees.add(new Employee("Thomas cook", "thomas@example.com",
 31 |                 dateOfBirth.getTime(), 1500000.0));
 32 | 
 33 |         dateOfBirth.set(1987, 4, 18);
 34 |         employees.add(new Employee("Steve Maiden", "steve@example.com",
 35 |                 dateOfBirth.getTime(), 1800000.0));
 36 |     }
 37 | 
 38 |     public static void main(String[] args) throws IOException, InvalidFormatException {
 39 | 
 40 |         // Create a Workbook
 41 |         Workbook workbook = new XSSFWorkbook();     // new HSSFWorkbook() for generating `.xls` file
 42 | 
 43 |         /* CreationHelper helps us create instances for various things like DataFormat,
 44 |            Hyperlink, RichTextString etc in a format (HSSF, XSSF) independent way */
 45 |         CreationHelper createHelper = workbook.getCreationHelper();
 46 | 
 47 |         // Create a Sheet
 48 |         Sheet sheet = workbook.createSheet("Employee");
 49 | 
 50 |         // Create a Font for styling header cells
 51 |         Font headerFont = workbook.createFont();
 52 |         headerFont.setBold(true);
 53 |         headerFont.setFontHeightInPoints((short) 14);
 54 |         headerFont.setColor(IndexedColors.RED.getIndex());
 55 | 
 56 |         // Create a CellStyle with the font
 57 |         CellStyle headerCellStyle = workbook.createCellStyle();
 58 |         headerCellStyle.setFont(headerFont);
 59 | 
 60 |         // Create a Row
 61 |         Row headerRow = sheet.createRow(0);
 62 | 
 63 |         // Creating cells
 64 |         for(int i = 0; i < columns.length; i++) {
 65 |             Cell cell = headerRow.createCell(i);
 66 |             cell.setCellValue(columns[i]);
 67 |             cell.setCellStyle(headerCellStyle);
 68 |         }
 69 | 
 70 |         // Cell Style for formatting Date
 71 |         CellStyle dateCellStyle = workbook.createCellStyle();
 72 |         dateCellStyle.setDataFormat(createHelper.createDataFormat().getFormat("dd-MM-yyyy"));
 73 | 
 74 |         // Create Other rows and cells with employees data
 75 |         int rowNum = 1;
 76 |         for(Employee employee: employees) {
 77 |             Row row = sheet.createRow(rowNum++);
 78 | 
 79 |             row.createCell(0)
 80 |                     .setCellValue(employee.getName());
 81 | 
 82 |             row.createCell(1)
 83 |                     .setCellValue(employee.getEmail());
 84 | 
 85 |             Cell dateOfBirthCell = row.createCell(2);
 86 |             dateOfBirthCell.setCellValue(employee.getDateOfBirth());
 87 |             dateOfBirthCell.setCellStyle(dateCellStyle);
 88 | 
 89 |             row.createCell(3)
 90 |                     .setCellValue(employee.getSalary());
 91 |         }
 92 | 
 93 |         // Resize all columns to fit the content size
 94 |         for(int i = 0; i < columns.length; i++) {
 95 |             sheet.autoSizeColumn(i);
 96 |         }
 97 | 
 98 |         // Write the output to a file
 99 |         FileOutputStream fileOut = new FileOutputStream("poi-generated-file.xlsx");
100 |         workbook.write(fileOut);
101 |         fileOut.close();
102 | 
103 |         workbook.close();
104 |     }
105 | 
106 | 
107 |     // Example to modify an existing excel file
108 |     private static void modifyExistingWorkbook() throws InvalidFormatException, IOException {
109 |         // Obtain a workbook from the excel file
110 |         Workbook workbook = WorkbookFactory.create(new File("existing-spreadsheet.xlsx"));
111 | 
112 |         // Get Sheet at index 0
113 |         Sheet sheet = workbook.getSheetAt(0);
114 | 
115 |         // Get Row at index 1
116 |         Row row = sheet.getRow(1);
117 | 
118 |         // Get the Cell at index 2 from the above row
119 |         Cell cell = row.getCell(2);
120 | 
121 |         // Create the cell if it doesn't exist
122 |         if (cell == null)
123 |             cell = row.createCell(2);
124 | 
125 |         // Update the cell's value
126 |         cell.setCellType(CellType.STRING);
127 |         cell.setCellValue("Updated Value");
128 | 
129 |         // Write the output to a file
130 |         FileOutputStream fileOut = new FileOutputStream("existing-spreadsheet.xlsx");
131 |         workbook.write(fileOut);
132 |         fileOut.close();
133 | 
134 |         // Closing the workbook
135 |         workbook.close();
136 |     }
137 | }
138 | 
139 | 
140 | class Employee {
141 |     private String name;
142 | 
143 |     private String email;
144 | 
145 |     private Date dateOfBirth;
146 | 
147 |     private double salary;
148 | 
149 |     public Employee(String name, String email, Date dateOfBirth, double salary) {
150 |         this.name = name;
151 |         this.email = email;
152 |         this.dateOfBirth = dateOfBirth;
153 |         this.salary = salary;
154 |     }
155 | 
156 |     public String getName() {
157 |         return name;
158 |     }
159 | 
160 |     public void setName(String name) {
161 |         this.name = name;
162 |     }
163 | 
164 |     public String getEmail() {
165 |         return email;
166 |     }
167 | 
168 |     public void setEmail(String email) {
169 |         this.email = email;
170 |     }
171 | 
172 |     public Date getDateOfBirth() {
173 |         return dateOfBirth;
174 |     }
175 | 
176 |     public void setDateOfBirth(Date dateOfBirth) {
177 |         this.dateOfBirth = dateOfBirth;
178 |     }
179 | 
180 |     public double getSalary() {
181 |         return salary;
182 |     }
183 | 
184 |     public void setSalary(double salary) {
185 |         this.salary = salary;
186 |     }
187 | }
188 | 


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