手写插入排序

public class InsertionSort {
    public void insertSort(int[] arr){
        if(arr==null||arr.length<2){
            return;
        }
        for (int i = 1; i <arr.length ; i++) {
            int j=i;
            while(j>0&&arr[j]<arr[j-1]){
                swap(arr,j,j-1);
                j--;
            }
        }
    }

    private void swap(int[] arr, int j, int i) {
        int tmp=arr[i];
        arr[i]=arr[j];
        arr[j]=tmp;
    }

    @Test
    public void test(){
        int[] n= new int[]{3,7,8,1,2};
        insertSort(n);

        for (int i = 0; i <n.length ; i++) {
            System.out.println(n[i]);
        }
    }
}