├── 2d spiral matrix.java
├── Arrays.java
├── JAVA.java
├── String operations.java
├── area of rectangle.java
├── comparing two arrays.java
├── java basic program.java
├── java recursion.java
├── pattern program.java
└── reversing an array.java


/2d spiral matrix.java:
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 1 | import java.util.*;
 2 | class spiral_matrix {
 3 |     public static void main(String [] args)
 4 |     {
 5 |       Scanner sc=new Scanner(System.in);  
 6 |       int row=sc.nextInt();
 7 |       int col=sc.nextInt();
 8 |       int [][] arr=new int[row][col];
 9 |       for(int i=0;i<arr.length;i++)
10 |       {
11 |         for(int j=0;j<arr.length;j++)
12 |         {
13 |             arr[i][j]=sc.nextInt();
14 |         }
15 |       }
16 |      int top=0;
17 |      int bot=col-1;
18 |      int left=0;
19 |      int right=row-1;
20 |      int d=1;
21 |      while(top<=bot && left<=right)
22 |      {
23 |         if(d==1)
24 |         {
25 |             for(int i=left;i<=right;i++)
26 |             {
27 |                 System.out.println(arr[top][i]);
28 | 
29 |             }
30 |             top++;
31 | 
32 |         }
33 |         if(d==2)
34 |         {
35 |             for(int i=top;i<=bot;i++)
36 |             {
37 |                 System.out.println(arr[i][right]);
38 |             }
39 |             right--;
40 |         }
41 |         if(d==3)
42 |         {
43 |             for(int i=right;i>=left;i--)
44 |             {
45 |                 System.out.println(arr[bot][i]);
46 |             }
47 |             bot--;
48 |         }
49 |         if(d==4)
50 |         {
51 |             for(int i=bot;i>=top;i--)
52 |             {
53 |                 System.out.println(arr[i][left ]);
54 | 
55 |             }
56 |             left++;
57 |         }
58 |         d++;
59 |         if(d==5)
60 |         {
61 |             d=1;
62 |         }
63 |      }
64 | 
65 |     }
66 |     
67 | }
68 | 


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/Arrays.java:
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 1 | 
 2 | import java.util.Arrays;
 3 | 
 4 | public class main 
 5 | {
 6 |    public static void a()//checking 2 arrays are equal
 7 |     {
 8 |       int[] nums={1,2,3,3,4};
 9 |       int[] nums1={1,2,3,3,4};
10 |      boolean r= Arrays.equals(nums,nums1);
11 |      if(r)
12 |      {
13 |          System.out.println("equal");
14 |      }
15 |      else
16 |      {
17 |         System.out.println("not equal");
18 |      }
19 |       
20 |     }
21 |     
22 |      public static void b()//array sorting
23 |     {
24 |         int[] n1={156,666,434,222};
25 |         Arrays.sort(n1);
26 |         for(int n:n1)
27 |         {
28 |             System.out.print(n+" ");
29 |         }
30 |         System.out.println();
31 |     }
32 |     
33 |     
34 |     
35 |     
36 | public static void c()//array addition and average
37 | {
38 | int nums[]={54,21,66,55};
39 | int sum=0;
40 | for(int i=0;i<nums.length;i++)
41 | {
42 | sum=sum+nums[i];
43 | }
44 | System.out.println(sum);
45 | System.out.println(sum/nums.length);
46 | }
47 | 
48 | 
49 | 
50 | 
51 |     public static void main(String[] args)
52 |     {
53 |         a();
54 |         b();
55 |         c();
56 |     }
57 | }
58 | 


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/JAVA.java:
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1 | 
2 | 


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/String operations.java:
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 1 | public class g
 2 |  {
 3 |     public static void main(String[] args) {
 4 |         StringBuilder sb=new StringBuilder("JOE");
 5 |         sb.append("movie");
 6 |         System.out.println("after appending:" + sb);
 7 |         sb.insert(3,"is a");
 8 |         System.out.println("After indexing:" +sb);
 9 |         sb.replace(0,2,"kgf");
10 |         System.out.println("After replacing:" +sb);
11 |         sb.delete(4,7);
12 |         System.out.println("After deleting:" +sb);
13 |         sb.reverse();
14 |         System.out.println("After reversing:" +sb);
15 |         int capacity=sb.capacity();
16 |         System.out.println("Current capacity:" +capacity);
17 |         int length=sb.length();
18 |         System.out.println("String length:" +length);
19 |         char charAt7=sb.charAt(7);
20 |         System.out.println("character at given index:" +charAt7);
21 |         sb.setCharAt(5,'v');
22 |         System.out.println("After changing char at given index:" +sb);
23 |         String Substring=sb.substring(5,6);
24 |         System.out.println("printing substring for given range:" +Substring);
25 |         int n=sb.indexOf("movie");
26 |         System.out.println("printing index:" +n);
27 |         sb.deleteCharAt(6);
28 |         System.out.println("After deleting character:" +sb);
29 |         String result=sb.toString();
30 |         System.out.println("Final string:" +result);
31 |     }
32 |     
33 | }
34 | 


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/area of rectangle.java:
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 1 | import java.util.Scanner;
 2 | class Main{
 3 | public static int area_of_rectangle(int a,int b)
 4 | {
 5 | int area=a*b;
 6 | return area;
 7 | }
 8 | public static void main(String[] args)
 9 | {
10 | Scanner sc=new Scanner(System.in);
11 | int a=sc.nextInt();
12 | int b=sc.nextInt();
13 | int r=area_of_rectangle(a,b);
14 | System.out.println(r);
15 | }
16 | }
17 | 


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/comparing two arrays.java:
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 1 |  class Main{
 2 |     public static void main(String[] args) {
 3 |         Scanner sc=new Scanner(System.in);
 4 |             int a=sc.nextInt();
 5 |             int b=sc.nextInt();
 6 |             int[] arr=new int[a];
 7 |             int[] arr1=new int[b];
 8 |             for(int j=0;j<a;j++)
 9 |             {
10 |              arr[j]=sc.nextInt(); 
11 |               
12 |             }
13 |               for(int j=0;j<b;j++)
14 |             {
15 |              arr1[j]=sc.nextInt(); 
16 |               
17 |             }
18 |             for(int i=0;i<a;i++)
19 |             {
20 |                 for(int j=0;j<b;j++)
21 |                 {
22 |                     if(arr[i]==arr1[j])
23 |                     {
24 |                         System.out.print(arr[i]+" ");
25 |                         arr1[j]=0;
26 |                     }
27 |                 }
28 |             }
29 |         
30 | 
31 |     }
32 | }
33 | 


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/java basic program.java:
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 1 | import java.util.Scanner;
 2 | class Main{
 3 |     public static void main(String[] args)
 4 |     {
 5 |         Scanner pg=new Scanner(System.in);
 6 |         int a=pg.nextInt();
 7 |         int b=pg.nextInt();
 8 |         System.out.println("1.Addition");
 9 |         System.out.println("2.Subtraction");
10 |         System.out.println("3.Multiplication");
11 |         System.out.println("4.Division");
12 |         System.out.println("5.Quit");
13 |         System.out.println("Enter your choice");
14 |        
15 |        while(true){
16 |             int choice=pg.nextInt();
17 |         if(choice==1)
18 |         {
19 |             System.out.println("adding:"+(a+b));
20 |         }
21 |          else if(choice==2)
22 |         {
23 |             System.out.println("subtracting:"+(a-b));
24 |         }
25 |          else if(choice==3)
26 |         {
27 |             System.out.println("multiplying:"+(a*b));
28 |         }
29 |          else if(choice==4)
30 |         {
31 |             System.out.println("dividing:"+(a/b));
32 |         }
33 |         else
34 |         {
35 |             break;
36 |         }
37 |        }
38 |     }
39 | }
40 | 


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/java recursion.java:
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 1 | import java.util.*;
 2 | class Main {
 3 | 
 4 | 
 5 | // direct recursion
 6 |     public static void direct_recursion(int n)
 7 |     {
 8 |       if(n==0) return;
 9 |       System.out.println(n);
10 |       direct_recursion(n-1);
11 |     }
12 | 
13 | 
14 | //indirect recursion
15 |     public static void indirect_recursionA(int k)
16 |     {
17 |      if(k<0) return;
18 |      System.out.println(k);
19 |      indirect_recursionB(k-2);
20 |     }
21 |     public static void indirect_recursionB(int k)
22 |     {
23 |     if(k<0) return;
24 |      System.out.println(k);
25 |      indirect_recursionC(k-2);
26 |     }
27 |     public static void indirect_recursionC(int k)
28 |     {
29 |      if(k<0) return;
30 |      System.out.println(k);
31 |      indirect_recursionA(k-6);
32 |     }
33 | 
34 |     
35 | //non-tail recursion
36 |     public static int factorial(int g)
37 |     {
38 |         if(g==1) return 1;
39 |         return g*factorial(g-1);
40 |     }
41 |     public static int sum_of_digit(int g)
42 |     {
43 |         if(g==1) return 1;
44 |         return g+sum_of_digit(g-1);
45 |     }
46 |     public static int square(int p,int o)
47 |     {
48 |         if(o==0) return 1;
49 |         return p*(square(p,o-1));
50 |     }
51 |     public static int sum(int l,int n)
52 |     {
53 |         if(l==0) return n;
54 |         return sum(l/10,n+1);
55 | 
56 |     }
57 | 
58 |     
59 | 
60 | 
61 |     public static void main(String[] args) {
62 |             Scanner sc=new Scanner(System.in);
63 |             System.out.println("enter number for direct recursion: ");
64 |             int a=sc.nextInt();
65 |             direct_recursion(a);
66 | 
67 | 
68 | 
69 |             System.out.println("enter number for indirect recursion : ");
70 |             int b=sc.nextInt();
71 |             indirect_recursionA(b);
72 | 
73 | 
74 |             
75 |             System.out.println("factorial: ");
76 |             int c=sc.nextInt();
77 |             System.out.println(factorial(c));
78 |             System.out.println(" sum of numbers: ");
79 |             int d=sc.nextInt();
80 |             System.out.println(sum_of_digit(d));
81 |             System.out.println("power of a and b numbers: ");
82 |             int e=sc.nextInt();
83 |             int f=sc.nextInt();
84 |             System.out.println(square(e,f));
85 |             System.out.println("number of digit: ");
86 |             int number=sc.nextInt();
87 |             int sum=0;
88 |             System.out.println(sum(number,sum));
89 |         }
90 | }
91 | 


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/pattern program.java:
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 1 | import java.util.Scanner;
 2 | class Main{
 3 | 
 4 | public static void z(int size)
 5 | {
 6 | for(int i=0;i<size;i++)
 7 | {
 8 |    for(int j=0;j<size;j++)
 9 |     {
10 |     System.out.print("*");
11 |     }
12 | System.out.println(); 
13 | }
14 | }
15 | 
16 | public static void y(int a)
17 | {
18 | for(int i=1;i<=a;i++)
19 |  {
20 | for(int k=a-1;k>=i;k--)
21 | {
22 | System.out.print(" ");
23 | }
24 |  for(int j=1;j<=i;j++)
25 | {
26 | System.out.print("* ");
27 | }
28 | 
29 | System.out.println();
30 | }
31 | }
32 | 
33 | 
34 | public static void x(int a)
35 | {
36 |  for(int i=a;i>=1;i--)
37 |    {
38 |        for(int j=0;j<a-i;j++)
39 |        {
40 |            System.out.print(" ");
41 |        }
42 |        for(int j=a;j>=a-i+1;j--)
43 |        {
44 |            System.out.print("* ");
45 |        }
46 |        System.out.println();
47 |        
48 |    }
49 | }
50 | 
51 | 
52 | public static void main(String[] args)
53 | {
54 | System.out.println("1.square pattern");
55 | System.out.println("2.triangle pattern");
56 | System.out.println("3.reverse triangle pattern");
57 | Scanner sc=new Scanner(System.in);
58 | System.out.println("Enter your choice:");
59 | int choice=sc.nextInt();
60 | while(true){
61 | if(choice==1)
62 | {
63 | int size=sc.nextInt();
64 | z(size);
65 | }
66 | else if(choice==2)
67 | {
68 | int a=sc.nextInt();
69 | y(a);
70 | }
71 | else if(choice==3)
72 | {
73 | int a=sc.nextInt();
74 | x(a);
75 | }
76 | else
77 | {
78 | break;
79 | }
80 | }
81 | }
82 | }
83 | 


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/reversing an array.java:
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 1 | import java.util.*;
 2 |  class Main{
 3 |     public static void main(String[] args) {
 4 |         Scanner sc=new Scanner(System.in);
 5 |         
 6 |        
 7 |             int a=sc.nextInt();
 8 |             int[] arr=new int[a];
 9 |             for(int j=0;j<a;j++)
10 |             {
11 |              arr[j]=sc.nextInt(); 
12 |               
13 |             }
14 |             for(int j=arr.length-1;j>=0;j--)
15 |             {
16 |                 System.out.print(arr[j]+" ");
17 |             }
18 |             System.out.println();
19 |         
20 | 
21 |     }
22 | }
23 | 


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