直接插入排序

public class InsertSort {

public static void insert(int[] a){
    if(a == null){
        throw new RuntimeException("输入数组");
    }

    if(a.length <= 1){
        return;
    }

    for(int j = 1;j<a.length;j++){
        int temp = a[j];
        int i;

        for(i = j-1;i>=0 && a[i]>temp;i--){
            a[i+1] = a[i];
        }

        //不满足上面for循环的话,元素不动
        a[i+1] = temp;
    }
}

public static void main(String[] args){
    int[] a = {4,2,2,2,1,5,7,6};
    InsertSort.insert(a);
    System.out.println(Arrays.toString(a));
}
}