Finding min and max value in each column in array

Artur Malka :

I have a problem with my program. I want to print min and max in each column but It doesn't work properly. I think everything should be ok. When the loop comes to end I restart min and max value.

public class tablice2 {
  public static void main(String[] args){
      int t [][] = new int [5][5];
      int n [] = new int [5];
      int x [] = new int [5];
      Random r = new Random();
      int min  = t[0][0];
      int max = t[0][0];


      for (int i = 0; i <t.length ;i++){
          min = 0;
          max = 0;
          for(int j = 0; j < t[i].length ;j++){
            t[i][j] = r.nextInt(6)-5;
              System.out.print(t[i][j] + " ");

              if (t[j][i] < min){
                  min = t[j][i];
              }

              if (t[j][i] > max){
                  max = t[j][i];
              }

          }
          n[i]=min;
          x[i]=max;


          System.out.println(" ");
      }

      for(int p=0;p<x.length;p++){
          System.out.println("Max Column "+p + ": " +x[p] );
      }

      for(int k=0;k<n.length;k++){
          System.out.println("Min Column "+k + ": " +n[k]);
      }



  }
}

Arvind Kumar Avinash :

Do not input and sort at the same time as the elements may still be initialized with the default values (i.e 0). Also, in the outer loop, reset max and min to the first element of the column.

Do it as follows:

import java.util.Random;

public class Main {
    public static void main(String[] args) {
        int t[][] = new int[5][5];
        int n[] = new int[5];
        int x[] = new int[5];
        Random r = new Random();
        int min;
        int max;

        for (int i = 0; i < t.length; i++) {
            for (int j = 0; j < t[i].length; j++) {
                t[i][j] = r.nextInt(10) - 5;
                System.out.printf("%4d", t[i][j]);
            }
            System.out.println();
        }

        for (int i = 0; i < t.length; i++) {
            min = t[0][i];
            max = t[0][i];
            for (int j = 0; j < t[i].length; j++) {
                if (t[j][i] < min) {
                    min = t[j][i];
                }
                if (t[j][i] > max) {
                    max = t[j][i];
                }
            }
            n[i] = min;
            x[i] = max;
        }

        for (int p = 0; p < x.length; p++) {
            System.out.println("Max Column " + p + ": " + x[p]);
        }

        for (int k = 0; k < n.length; k++) {
            System.out.println("Min Column " + k + ": " + n[k]);
        }
    }
}

A sample run:

   3  -4   2   0   1
  -2  -2   4  -1  -2
  -3   1   4  -1   0
  -4   4  -2  -5   2
  -5  -3  -3  -4  -1
Max Column 0: 3
Max Column 1: 4
Max Column 2: 4
Max Column 3: 0
Max Column 4: 2
Min Column 0: -5
Min Column 1: -4
Min Column 2: -3
Min Column 3: -5
Min Column 4: -2

Notes:

1. I have changed r.nextInt(6)-5 to r.nextInt(10) - 5 in order to produce a mix of negative, 0 and positive numbers so that you can quickly validate the result. You can change it back to r.nextInt(6)-5 as per your requirement.
2. I have also used printf instead of print to print each number with a space of 4 units. You can change it back to print if you wish so.
3. Use of Integer.MAX_VALUE and/or Integer.MIN_VALUE is not required at all to solve this problem.

Feel free to comment in case of any doubt.