Java program crashes with StackOverflow when using bubble sort of a large array

Question

I have written a small Java program implementing the bubble sort technique for int arrays. It works for arrays of 1000 units, but when I increase it to 10 000, it crashes with java.lang.StackOverflowError.

Here is the code:

import java.util.*;
import java.lang.*;

class BubbleSort
{
  public static void main (String [] argv)
  {
    int Array [] = new int [10000];
    for (int a = 0; a < 10001; a++)
    {
    Array[a] = (int) (Math.random()*100);
    }  
    // generated an array of 10000 units and filled with random numbers

    for (int end = Array.length-1; end >= 0; end--)
    {
      BubbleSort (Array, 0, end);
    }

  }


  public static int BubbleSort (int A [], int count, int end)
  {

    if (count == end) //debugger says crash occurs here
    {
      return count;
    }

    else
    {

       if (A[count] > A[count+1])
       {
         int temp = A[count];
         A[count] = A[count+1];
         A[count+1] = temp;

         return BubbleSort(A, count+1, end); //and here

       }

     else
     {
        return BubbleSort(A, count+1, end);
     }
  } 

 }
}

Any help very appreciated!

Answer 1

Keeping aside the logic, the technical reason as to why it fails at 10000 is because each thread in Java has a fixed stack size. And when you use 10000 it is unable to find enough memory.

Use -XX:ThreadStackSize=512 to increase the default memory that JVM allocates to threads and it may work. But generally you don't have to bother about it.

On a sidenote check whether you really require recursion over here.