2D array in Java

1 . Write a java program to print all elements of an array

public class printAllElements 
{
   public static void main(String[] args) 
   { 
      int [][]arr = {{1,2},{3,4},{5,6}};
      for(int row = 0; row < arr.length; row++) 
      {
          for(int col = 0; col < arr[0].length; col++)
          {
             System.out.print(arr[row][col]+" ");
          }
          System.out.println();
     }
  }
}

2 . Write a java program to print first and last row of an array

public class print1StAndLast
{
   public static void main(String[] args) 
   { 
      int [][]arr = {{1,2,3},{4,5,6},{7,8,9}};
      for(int row = 0; row < arr.length; row++) 
      {
         for(int col = 0; col < arr[0].length; col++)
         {
            if(row==0 || row==arr.length-1)
               System.out.print(arr[row][col]+" ");
         }
         System.out.println();
     }
  }
}

3 . Write a java program to print first and last row of an array

public class borderElements
{
    public static void main(String[] args) 
    { 
       int [][]arr = {{1,2,3},{4,5,6},{7,8,9}};
       for(int row = 0; row < arr.length; row++) 
       {
          for(int col = 0; col < arr[0].length; col++)
          {
              if(row==0 || row==arr.length-1 || col==0||col==arr[0].length-1)
                  System.out.print(arr[row][col]+" ");
              else
                  System.out.print(" ");
          }
          System.out.println();
      }
   }
}

4 . Write a java program to print only diagonal elements of an array

public class onlyDiagonal
{
    public static void main(String[] args) 
    { 
        int [][]arr = {{1,2,3},{4,5,6},{7,8,9}};
        for(int row = 0; row < arr.length; row++) 
        {
            for(int col = 0; col < arr[0].length; col++)
            {
               if(row==col || row+col==arr.length-1)
                  System.out.print(arr[row][col]+" ");
               else
                  System.out.print(" ");
            }
            System.out.println();
        }
    }
}

5 . Write a java program to print all elements below the major Diagonal of an array

public class majorDiagonal
{
   public static void main(String[] args) 
   { 
      int [][]arr = {{1,2,3},{4,5,6},{7,8,9}};
      for(int row = 0; row < arr.length; row++) 
      {
         for(int col = 0; col < arr[0].length; col++)
         {
            if(row>=col)
               System.out.print(arr[row][col]+" ");
            else
               System.out.print(" ");
         }
         System.out.println();
      }
   }
}

6 . Write a java program to print all elements above the major Diagonal of an array

public class aboveMajorDiagonal
{
   public static void main(String[] args) 
   { 
      int [][]arr = {{1,2,3},{4,5,6},{7,8,9}};
      for(int row = 0; row < arr.length; row++) 
      {
          for(int col = 0; col < arr[0].length; col++)
          {
              if(row<=col)
                 System.out.print(arr[row][col]+" ");
              else
                 System.out.print(" ");
          }
          System.out.println();
      }
   }
}

7 . Write a java program to print all even elements of an array

public class evenElements
{
   public static void main(String[] args) 
   { 
       int [][]arr = {{1,2,3},{4,5,6},{7,8,9}};
       for(int row = 0; row < arr.length; row++) 
       {
          for(int col = 0; col < arr[0].length; col++)
          {
              if(arr[row][col]%2==0)
                 System.out.print(arr[row][col]+" ");
              else
                 System.out.print(" ");
          }
          System.out.println();
       }
   }
}

8 . Write a java program to multiply all elements of an array by 10

import java.util.*; 
public class MultiplyBy10
{
   void alterArr(int[][]arr){
      for(int row = 0; row < arr.length; row++) 
      {
         for(int col = 0; col < arr[0].length; col++)
         {
             System.out.println(arr[row][col]*=10);
         }
      }
   }
}

9 . Write a java program to replace all negative elements of an array by 0 (zero).

public class ReplaceNegativeElem
{
   void alterArr(int[][] arr)
   {
       for(int row=0; row<arr.length;row++) {
          for (int col=0;col<arr[0].length;col++) {
             if(arr[row][col] < 0)
                 arr[row][col] = 0; 
                 System.out.println(arr[row][col]);
          }
       }
   }
}

10 . Write a java program to swap first row with last row

public class Swap1rowWithLast
{
   void alterArr(int [][] arr) {
     int row1 = 0;
     int row2 = arr.length -1;
     for (int col=0;col<arr[0].length;col++) {
        int temp = arr[row1][col];
        arr[row1][col] = arr[row2][col];
        arr[row2][col] = temp;
    }
    for(int row=0; row<arr.length;row++) {
      for (int col=0;col<arr[0].length;col++) {
         System.out.print(arr[row][col]+ " "); 
      }
      System.out.println();
    }
  }
}

11 . Write a java program to swap first column with last column

public class Swap1stColWithLastCol
{
    void alterArr(int [][] arr) {
       int col1 = 0;
       int col2 = arr[0].length -1;
       for (int row=0;row<arr.length;row++) {
          int temp = arr[row][col1];
          arr[row][col1] = arr[row][col2];
          arr[row][col2] = temp;
       }
    }
    public static void main(String[] args)
    {
        Swap1stColWithLastCol sw = new Swap1stColWithLastCol();
        int [][] arr = {{1,2,3},{4,5,6},{7,8,9}};
        sw.alterArr(arr);
        for(int row=0; row<arr.length;row++) {
           for (int col=0;col<arr[0].length;col++) {
              System.out.print(arr[row][col]+ " "); 
           } 
           System.out.println();
        }
    }
}

12 . Write a java program to circular shift the array up

public class CircularShift
{
   void alterArr(int [][] arr) {
     for(int row=0; row<arr.length-1;row++) {
        for (int col=0;col<arr[0].length;col++){
           int temp = arr[row][col];
           arr[row][col] = arr[row+1][col];
           arr[row+1][col] = temp;
        }
     }
     for(int row=0; row<arr.length;row++) {
        for (int col=0;col<arr[0].length;col++) {
           System.out.print(arr[row][col]+ " "); 
        }
        System.out.println();
     }
  }
}

13 . Write a java program to Circular shift the array down

public class CircularShiftDown1
{
   void alterArr(int [][] arr) {
      for(int row=arr.length-1; row>0;row--) {
         for (int col=0;col<arr[0].length;col++){
            int temp = arr[row][col];
            arr[row][col] = arr[row-1][col];
            arr[row-1][col] = temp;
         }
      }
      for(int row=0; row<arr.length;row++) {
         for (int col=0;col<arr[0].length;col++) {
            System.out.print(arr[row][col]+ " "); 
         }
         System.out.println();
      }
   }
}

14 . Write a java program to shift the array one column left

public class ShiftArrayLeft
{
    void alterArr(int [][] arr) {
       for(int row=0; row<arr.length;row++) {
          for (int col=0;col<arr[0].length-1;col++){
             int temp = arr[row][col];
             arr[row][col] = arr[row][col+1];
             arr[row][col+1] = temp;
         }
      }
      for(int row=0; row<arr.length;row++) {
         for (int col=0;col<arr[0].length;col++) {
            System.out.print(arr[row][col]+ " "); 
         }
         System.out.println();
     }
  }
}

15 . Write a java program to create mirror image of array

public class MirrorImageOfTheArray
{
    void alterArr(int [][] arr) {
       for(int row=0; row<arr.length;row++) {
          for (int col=0;col<arr[0].length/2;col++){
             int temp = arr[row][col];
             arr[row][col] = arr[row][arr[0].length-1-col];
             arr[row][arr[0].length-1-col] = temp;
          }
       }
       for(int row=0; row<arr.length;row++) {
          for (int col=0;col<arr[0].length;col++) {
              System.out.print(arr[row][col]+ " "); 
          }
          System.out.println();
       }
   }
}

16 . Write a java program to create transpose of the array

public class TransposeImage
{
   void alterArr(int [][] arr, int [][] arr1) {
      for(int row=0; row<arr.length;row++) {
         for (int col=0;col<arr[0].length;col++){
            arr1[row][col] = arr[col][row];
         }
      }
      for(int row=0; row<arr1.length;row++) {
         for (int col=0;col<arr1[0].length;col++) {
            System.out.print(arr1[row][col]+ " "); 
         }
         System.out.println();
      }
    }
    public static void main (String[] args)
    {
        int arr[][] = { {1, 1, 1},{2, 2, 2},{3, 3, 3}};
        int arr1[][] = new int[3][3], i, j;
        TransposeImage t= new TransposeImage();
        t. alterArr(arr, arr1);
        for(int row=0; row<arr1.length;row++) {
            for (int col=0;col<arr1[0].length;col++) {
               System.out.print(arr1[row][col]+ " "); 
            }
            System.out.println();
        }
    }
}

17 . Write a java program to sort each row of the array

public class SortEachRow
{
   void alterArr(int [][] arr) {
     for(int row=0; row<arr.length;row++) {
       for (int col=0;col<arr[0].length/2;col++){
          for (int k=0; k<arr.length-col-1; k++) {
             if (arr[row][k] > arr[row][k + 1]) {
                int t = arr[row][k]; 
                arr[row][k] = arr[row][k + 1];
                arr[row][k + 1] = t;
             }
          }
        }
     }
     for(int row=0; row<arr.length;row++) {
        for (int col=0;col<arr[0].length;col++) {
           System.out.print(arr[row][col]+ " "); 
        }
        System.out.println();
     }
  }
}

18 . Write a java program to sort each column of the array

public class SortEachColumn
{
   void alterArr(int [][] arr) {
      for (int col=0;col<arr[0].length;col++) { 
         for (int row=0; row<arr.length;row++){
            for (int k=0; k<arr.length-row-1; k++) {
               if (arr[k][col] > arr[k + 1][col]) {
                  int t = arr[k][col]; 
                  arr[k][col] = arr[k + 1][col];
                  arr[k + 1][col] = t;
               }
            }
         }
      }
      for(int row=0; row<arr.length;row++) {
         for (int col=0;col<arr[0].length;col++) {
            System.out.print(arr[row][col]+ " "); 
         }
         System.out.println();
      }
   }
}

19 . Write a java program to find sum of diagonal elements in an array

public class SumDiagonalElements
{
   public static void main(String[] args)
   {
      int [][] arr = {{1,2},{3,4},{5,6}};
      int sum = 0;
      for(int row=0; row<arr.length;row++) {
         for (int col=0;col<arr[0].length;col++) {
            if(row==col || row+col+1==arr.length)
               sum+= arr[row][col]; 
         }
         System.out.println("Sum = "+sum);
      }
   }
}

20 . Write a java program to find sum of each row in an array

public class sumOfEachRow
{
    public static void main(String[] args)
    {
       int [][] arr = {{1,2},{3,4},{5,6}};
       for(int row=0; row<arr.length;row++) {
          int sum = 0;
          for (int col=0;col<arr[0].length;col++) {
             sum+= arr[row][col]; 
          }
          System.out.println("Sum = "+sum);
       }
    }
}

21 . Write a java program to find sum of each Columns in an array

public class sumOfAllColumns
{
   public static void main(String[] args)
   {
      int [][] arr = {{1,2},{3,4},{5,6}};
      for(int col=0;col<arr[0].length;col++) {
        int sum = 0;
        for (int row=0; row<arr.length;row++) {
           sum+= arr[row][col]; 
        }
        System.out.println("Sum = "+sum);
     }
  }
}

22 . Write a java program to find Minimum of all elements in an array

public class MinInEachRow
{
   public static void main(String[] args)
   {
      int [][] arr = {{1,2,0},{10,3,4},{5,11,6}};
      int min = arr[0][0];
      for (int row=0; row<arr.length;row++) {
        for(int col=0;col<arr[0].length;col++) {
           if(arr[row][col]<min)
              min = arr[row][col]; 
        }
        System.out.println("Min = "+min);
     }
   }
}

23 . Write a java program to find Maximum of all elements in an array

public class MaxOFAll
{
   public static void main(String[] args)
   {
      int [][] arr = {{1,2,0},{10,3,4},{5,11,6}};
      int max = arr[0][0];
      for (int row=0; row<arr.length;row++) {
        for(int col=0;col<arr[0].length;col++) {
          if(arr[row][col]>max)
             max = arr[row][col]; 
          }
          System.out.println("Max = "+max);
       }
   }
}

24 . Write a java program to find Minimum of each row in an array

public class MinInEachRow
{
   public static void main(String[] args)
   {
      int [][] arr = {{1,2,0},{10,3,4},{5,11,6}};
      for (int row=0; row<arr.length;row++) {
         int min= arr[row][0];
         for(int col=0;col<arr[0].length;col++) {
            if(arr[row][col]<min)
               min = arr[row][col]; 
            }
            System.out.println(row+"Min = "+min);
        }
    }
}

25 . Write a java program to find min of each row and its index in a new array

public class MinOfEachRow
{
   void alterArr(int [][] arr, int [][] mrow) {
      for(int row=0; row<arr.length;row++) {
         mrow[row][0] = arr[0][row];
         for(int col=0;col<arr[0].length;col++) {
            if(mrow[row][0] > arr[row][col]) {
               mrow[row][0] = arr[row][col];
               mrow[row][1] = col;
            }
         }
         System.out.print(" ");
      }
   }
   public static void main (String[] args)
   {
      int arr[][] = { {1, 4, 6},{10, 2, 8},{7, 5, 3}};
      int mrow[][] = new int[3][3];
      MinOfEachRow m= new MinOfEachRow();
      m. alterArr(arr, mrow);
      for(int row=0; row<mrow.length;row++) {
         for (int col=0;col<mrow[0].length;col++) {
           System.out.print(mrow[row][col]+ " "); 
         }
         System.out.println();
     }
  }
}

26 . Write a java program to find max of each col and its index in a new array

public class maxOfEachColumn1
{
   void alterArr(int [][] arr, int [][] mcol) {
      for(int col=0;col<arr[0].length;col++) {
         mcol[col][0] = arr[0][col];
         for (int row=0; row<arr.length;row++){
            if(mcol[col][0] < arr[row][col]) {
               mcol[col][0] = arr[row][col];
               mcol[col][1] = row;
            }
         }
      } 
   }
   public static void main (String[] args)
   {
      int arr[][] = { {1, 4, 6},{10, 2, 8},{7, 5, 3}};
      int mcol[][] = new int[3][3];
      maxOfEachColumn1 s= new maxOfEachColumn1();
      s. alterArr(arr, mcol);
      for(int row=0; row<mcol.length;row++) {
         for (int col=0;col<mcol[0].length;col++) {
            System.out.print(mcol[row][col]+ " "); 
         }
         System.out.println();
      }
   }
}

27 . Write a java program to count all even elements in an array

public class countAllEvenElements
{
    public static void main(String[] args)
    {
        int [][] arr = {{1,2,3},{4,5,6},{7,8,9}}; 
        int count=0;
        for(int row=0; row<arr.length;row++) {
           for (int col=0;col<arr[0].length;col++) {
              if(arr[row][col]%2 == 0)
                 count++;
           }
        }
        System.out.print("count:"+count); 
   }
}f