如何理解这种冒泡数组排序

Question

How did it working when both the loop is starting from 0 and comparison between both indexes have the same value

public class BubbleSort {
    public static void main(String[] args)
    {
        int arr[]={5,1,2,1,1,4,4,4,4,4,3};

        for(int i=0;i<arr.length;i++)//i=0
        {
            for(int j=0;j<arr.length;j++)//j=0
            {
                if(arr[i]>arr[j])//i=5>j=5
                {
                   int temp=arr[i];
                   arr[i]=arr[j];
                   arr[j]=temp;
                }
            }
        }
        for(int k=0;k<arr.length;k++)
            System.out.println(arr[k]);
        }
    }
}

Answer 1

So, if I try to summarize your code:

1. There are two loops (with iterators i and j)

2. In the first for loop, we take each element of the array one by one and then we compare that element (lets call it 'current element') with other elements (including the 'current element', because it is possible that i and j have same values ie i=0, j=0; i=1, j=1) in the second for loop.

3. Now, in this comparison, if the 'current element' is greater than the elements we are comparing in the second for loop, then we swap the element.

4. So, as the execution continuous, the elements with bigger value will move towards the right side of the array and elements with smaller value will move towards left side of the array.

5. Eventually the array will be sorted.

Its called bubble sort, because the elements are sorted and move up to the array like bubbles.

You can find more info here: https://www.hackerearth.com/practice/algorithms/sorting/bubble-sort/tutorial/