为什么'i'的值打印3次，在插入排序算法中它应该只打印1次

Question

//programme of insertion sort i am checking how many times the value is printing //when i enter the 2 and 1 the value of i is printing 3 times but it should have to print 1 times when i enter 2 value

public class Insertionsort {

static void insertsort(int arr[]){

    for(int i=1;i<arr.length;i++) {
        for(int j=i-1;j>=0;) {
            System.out.println("i is"+i);
            if(arr[j]>arr[i] ) {
                int temp=arr[j];  //for swapping 
                arr[j]=arr[i];
                arr[i]=temp;
                i--;
            }else {
                j--;
            }
        }
    }
    for(int i=0;i<2;i++) {
    System.out.println(arr[i]);
    }
}

public static void main(String args[]) {
    int arr[]=new int[2];
    System.out.println("please Enter the value");
    Scanner sc= new Scanner(System.in);
    for(int i=0;i<2;i++) {
        arr[i]=sc.nextInt();

    }
    insertsort( arr);

}

}

Output please Enter the value 2 1 i is1 i is0 i is1 1 2

Answer 1

The println should be before the inner loop.

for(int i=1;i<arr.length;i++) {
    System.out.println("i is"+i);
    for(int j=i-1;j>=0;) {

You only want the value of i to be printed once each time i is updated. If you put it in the inner loop, then each value of i will be printed multiple times since the inner loop can iterate multiple times for each value of i .

Answer 2

For value 2,1 it's printing 3 times, because for i = 1, j= 0 it prints 1 times then goes inside if condition and makes value of i=0 and no change in value of j and now the value is 1 2 of the array as it is swap. Again it check condition for j>=0 which satisfies the for loop condition, it enter print 2nd times but this time it goes to else condition decreasing the value of j making it equal to j=-1, checks the condition and loop exit from inner loop.

At this point we have value of i =0, now it goes to outside loop increases value of i, ie makes value of i = 1, checks condition and then goes inside inside inner loop, with j= 0,check condition and then print 3rd times goes to else condition decreasing the value of j, breaking inner loop and then outer loop.

Try doing dry run or using debugger it will help!