冒泡排序

import java.util.Arrays;

public class BubbleSort {
    public static void main(String[] args) {
        int arr[] = {3, 9, -1, 10, 20};
        bubbleSort(arr);
        System.out.println(Arrays.toString(arr));
    }

    public static int[] bubbleSort ( int[] arr){
        int temp = 0;
        boolean flag = false;
        for (int i = 0; i <= arr.length; i++) {
            for (int j = 0; j < arr.length - 1 - i; j++) {
                if (arr[j] > arr[j + 1]) {
                    flag = true;
                    temp = arr[j];
                    arr[j] = arr[j + 1];
                    arr[j + 1] = temp;
                }
            }
            if (!flag) {
                break;
            } else {
                flag = false;
            }
        }
        return arr;
    }
}