Thread: Bubble Sort Help

Hi everyone,

I'm trying to do a bubble sort where it takes the largest element and takes it to the right. It works for the most part, but then for some reason the right-most element (after the sorting) becomes 0 and then it acts accordingly. It happens sometimes with arrays, so I don't really know why that is. Here are my bubblesort, swapping, and display codes:

    public void bubblesort()
    {
        int out,in;
 
        for(out=n;out>1;out--)
        {
            for(in=0;in<out;in++)
            {
                if(a[in]>a[in+1])
                {
                    swap(in,in+1);
                }
                display();
            }
        }
    }

    public void display()
    {
        for(int j=0;j<n;j++)
        {
            System.out.print(a[j] + " ");
        }
        System.out.println();
        System.out.println();
    }

    public void swap(int one,int two)
    {
        long temp=a[one];
        a[one]=a[two];
        a[two]=temp;
    }

Sure thing:

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package array;
 
/**
 *
 * @author ashwin
 */
public class Array 
{
    public long[] a;
    public int n;
 
    public Array(int max)
    {
        a=new long[max];
        n=0;
    }
 
    public void insertelement(int value)
    {
        a[n]=value;
        n++;
    }
 
    public void display()
    {
        for(int j=0;j<n;j++)
        {
            System.out.print(a[j] + " ");
        }
        System.out.println();
        System.out.println();
    }
 
    public void bubblesort()
    {
        int out,in;
 
        for(out=n;out>1;out--)
        {
            for(in=0;in<out;in++)
            {
                if(a[in]>a[in+1])
                {
                    swap(in,in+1);
                }
                display();
            }
        }
    }
 
    public void swap(int one,int two)
    {
        long temp=a[one];
        a[one]=a[two];
        a[two]=temp;
    }
}

Main Class:

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package array;
 
/**
 *
 * @author ashwin
 */
public class ArrayApp 
{
    public static void main(String[] args)
    {
        int m=15000;
        Array arr=new Array(m);
 
        arr.insertelement(10);
        arr.insertelement(15);
        arr.insertelement(14);
        arr.insertelement(-5);
        arr.insertelement(10);
        arr.insertelement(1);
        arr.insertelement(43);
        arr.insertelement(27);
        arr.insertelement(33);
        arr.insertelement(6);
        arr.insertelement(8);
        arr.insertelement(39);
 
        System.out.print("Original array: ");
        arr.display();
        System.out.println();
        System.out.println();
 
        arr.bubblesort();
 
        System.out.print("New Array: ");
        arr.display();
    }
}

Output:

run:
Original array: 10 15 14 -5 10 1 43 27 33 6 8 39 
 
 
 
10 15 14 -5 10 1 43 27 33 6 8 39 
 
10 14 15 -5 10 1 43 27 33 6 8 39 
 
10 14 -5 15 10 1 43 27 33 6 8 39 
 
10 14 -5 10 15 1 43 27 33 6 8 39 
 
10 14 -5 10 1 15 43 27 33 6 8 39 
 
10 14 -5 10 1 15 43 27 33 6 8 39 
 
10 14 -5 10 1 15 27 43 33 6 8 39 
 
10 14 -5 10 1 15 27 33 43 6 8 39 
 
10 14 -5 10 1 15 27 33 6 43 8 39 
 
10 14 -5 10 1 15 27 33 6 8 43 39 
 
10 14 -5 10 1 15 27 33 6 8 39 43 
 
10 14 -5 10 1 15 27 33 6 8 39 0 
 
10 14 -5 10 1 15 27 33 6 8 39 0 
 
10 -5 14 10 1 15 27 33 6 8 39 0 
 
10 -5 10 14 1 15 27 33 6 8 39 0 
 
10 -5 10 1 14 15 27 33 6 8 39 0 
 
10 -5 10 1 14 15 27 33 6 8 39 0 
 
10 -5 10 1 14 15 27 33 6 8 39 0 
 
10 -5 10 1 14 15 27 33 6 8 39 0 
 
10 -5 10 1 14 15 27 6 33 8 39 0 
 
10 -5 10 1 14 15 27 6 8 33 39 0 
 
10 -5 10 1 14 15 27 6 8 33 39 0 
 
10 -5 10 1 14 15 27 6 8 33 0 39 
 
-5 10 10 1 14 15 27 6 8 33 0 39 
 
-5 10 10 1 14 15 27 6 8 33 0 39 
 
-5 10 1 10 14 15 27 6 8 33 0 39 
 
-5 10 1 10 14 15 27 6 8 33 0 39 
 
-5 10 1 10 14 15 27 6 8 33 0 39 
 
-5 10 1 10 14 15 27 6 8 33 0 39 
 
-5 10 1 10 14 15 6 27 8 33 0 39 
 
-5 10 1 10 14 15 6 8 27 33 0 39 
 
-5 10 1 10 14 15 6 8 27 33 0 39 
 
-5 10 1 10 14 15 6 8 27 0 33 39 
 
-5 10 1 10 14 15 6 8 27 0 33 39 
 
-5 1 10 10 14 15 6 8 27 0 33 39 
 
-5 1 10 10 14 15 6 8 27 0 33 39 
 
-5 1 10 10 14 15 6 8 27 0 33 39 
 
-5 1 10 10 14 15 6 8 27 0 33 39 
 
-5 1 10 10 14 6 15 8 27 0 33 39 
 
-5 1 10 10 14 6 8 15 27 0 33 39 
 
-5 1 10 10 14 6 8 15 27 0 33 39 
 
-5 1 10 10 14 6 8 15 0 27 33 39 
 
-5 1 10 10 14 6 8 15 0 27 33 39 
 
-5 1 10 10 14 6 8 15 0 27 33 39 
 
-5 1 10 10 14 6 8 15 0 27 33 39 
 
-5 1 10 10 14 6 8 15 0 27 33 39 
 
-5 1 10 10 6 14 8 15 0 27 33 39 
 
-5 1 10 10 6 8 14 15 0 27 33 39 
 
-5 1 10 10 6 8 14 15 0 27 33 39 
 
-5 1 10 10 6 8 14 0 15 27 33 39 
 
-5 1 10 10 6 8 14 0 15 27 33 39 
 
-5 1 10 10 6 8 14 0 15 27 33 39 
 
-5 1 10 10 6 8 14 0 15 27 33 39 
 
-5 1 10 6 10 8 14 0 15 27 33 39 
 
-5 1 10 6 8 10 14 0 15 27 33 39 
 
-5 1 10 6 8 10 14 0 15 27 33 39 
 
-5 1 10 6 8 10 0 14 15 27 33 39 
 
-5 1 10 6 8 10 0 14 15 27 33 39 
 
-5 1 10 6 8 10 0 14 15 27 33 39 
 
-5 1 6 10 8 10 0 14 15 27 33 39 
 
-5 1 6 8 10 10 0 14 15 27 33 39 
 
-5 1 6 8 10 10 0 14 15 27 33 39 
 
-5 1 6 8 10 0 10 14 15 27 33 39 
 
-5 1 6 8 10 0 10 14 15 27 33 39 
 
-5 1 6 8 10 0 10 14 15 27 33 39 
 
-5 1 6 8 10 0 10 14 15 27 33 39 
 
-5 1 6 8 10 0 10 14 15 27 33 39 
 
-5 1 6 8 0 10 10 14 15 27 33 39 
 
-5 1 6 8 0 10 10 14 15 27 33 39 
 
-5 1 6 8 0 10 10 14 15 27 33 39 
 
-5 1 6 8 0 10 10 14 15 27 33 39 
 
-5 1 6 0 8 10 10 14 15 27 33 39 
 
-5 1 6 0 8 10 10 14 15 27 33 39 
 
-5 1 6 0 8 10 10 14 15 27 33 39 
 
-5 1 0 6 8 10 10 14 15 27 33 39 
 
-5 1 0 6 8 10 10 14 15 27 33 39 
 
-5 0 1 6 8 10 10 14 15 27 33 39 
 
New Array: -5 0 1 6 8 10 10 14 15 27 33 39

Originally Posted by Norm

Can you make a small complete program that compiles, executes and shows the problem?

I was able to see my mistake; it was that I iterated n from 0 to out, instead of out-1 because arrays start at 0. I can still post my code, if you would like me to so I can help others that make the same mistake.