Java 2D array: summing columns and displaying array problems -

when column count , row count same, code works fine. when differ throws exception inside columnsum method.

here's error message.

exception in thread "main" java.lang.arrayindexoutofboundsexception:

and here's code

public static void columnsum(int[][] anarray) {     int sum = 0;      (int col = 0; col < anarray.length; col++)      {         (int r = 0; r < anarray[col].length; r++)          {             sum += anarray[r][col];         }          system.out.println("sum of column " + col + " = " + sum);      }       system.out.println(); } 

i have no idea why code doesn't work when have more columns rows or vice versa.

does have idea?

change sum += anarray[r][col]

to sum += anarray[col][r]

this reason why runs when columns & rows of same size. when they're of different length, instance 5 cols & 3 rows, code try access anarray[3][5] in 1 of iterations , elements not exist, hence exception.