Question

I tried to make an implementation of bubble sort, but I am not sure whether it is correct or not. If you can give it a look and if it is a bubble sort and can be done in better way please don’t be shy. Here is the code:

package Exercises;

import java.util.*;

public class BubbleSort_6_18 
{
    public static void main(String[] args) 
    {
        Random generator = new Random();

        int[] list = new int[11];
        for(int i=0; i<list.length; i++)
        {
            list[i] = generator.nextInt(10);
        }

        System.out.println("Original Random array: ");
        printArray(list);

        bubbleSort(list);

        System.out.println("\nAfter bubble sort: ");
        printArray(list);
    }

    public static void bubbleSort(int[] list)
    {
        for(int i=0; i<list.length; i++)
        {
            for(int j=i + 1; j<list.length; j++)
            {
                if(list[i] > list[j])
                {
                    int temp = list[i];
                    list[i] = list[j];
                    list[j] = temp;
                }
            }

        }
    }

    public static void printArray(int[] list)
    {
        for(int i=0; i<list.length; i++)
        {
            System.out.print(list[i] + ", ");
        }
    }
}

Answer 1

This is the calssical implementation for bubble sort and it seems to be OK. There are several optimizations that can be done, but the overall idea is the same. Here are some ideas:

• If there is an iteration of the outer cycle when no swap is performed in the inner cycle, then break, no use to continue
• On each iteration of the outer cycle swap the direction of the inner one – do it once left to right and then do it once right to left(this helps avoid elements moving slowly towards the right end).