java 实现冒泡排序

1. 先循环一次将数组内部的最大元素排序到最后一位

import java.util.Arrays; 
public class Main {
	public static void main(String[] args) {
		int[] arr1 = {2, 5, 8, 4, 3};
		for (int i = 0; i < arr1.length - 1 ; i++){
            int tag ;
            if(arr1[i] > arr1[i+1]){
                tag = arr1[i];
                arr1[i] = arr1[i+1];
                arr1[i+1] = tag;
            }
		} 

	     System.out.println(Arrays.toString(arr1)); // [2, 5, 4, 3, 8]

	}
}

2. 我们在上面经过一次循环将8排序到了最后一位, 如果想将5排序到倒数第二位, 应该再走一次循环

import java.util.Arrays; 
public class Main {
	public static void main(String[] args) {
		int[] arr1 = {2, 5, 8, 4, 3};
		for (int i = 0; i < arr1.length - 1 ; i++){
            int tag ;
            if(arr1[i] > arr1[i+1]){
                tag = arr1[i];
                arr1[i] = arr1[i+1];
                arr1[i+1] = tag;
            }
		} 
	     System.out.println(Arrays.toString(arr1)); // [2, 5, 4, 3, 8]
		
		// 这里 -2 的目的是因为最后一位已经是排列的好的了, 不用再排序了
         for (int i = 0; i < arr1.length - 2 ; i++){
            int tag ;
            if(arr1[i] > arr1[i+1]){
                tag = arr1[i];
                arr1[i] = arr1[i+1];
                arr1[i+1] = tag;
            }
		} 
	     System.out.println(Arrays.toString(arr1)); // [2, 4, 3, 5, 8]

	}
}

3. 思考一下, 如果我想将剩下的 3 个元素排序是不是还要执行三遍的循环呢

import java.util.Arrays; 
public class Main {

    // 排序方法实现
    private static void sort (){
        int[] arr1 = {2, 5, 8, 4, 3};

        for(int j = 0; j < arr1.length - 1; j++){
            for (int i = 0; i < arr1.length -1 - j ; i++){
                int tag ;
                if(arr1[i] > arr1[i+1]){
                    tag = arr1[i];
                    arr1[i] = arr1[i+1];
                    arr1[i+1] = tag;
                }
		    }  
        }
      
	    System.out.println("排序结果" + Arrays.toString(arr1));
    }

	public static void main(String[] args) {
		int[] arr1 = {2, 5, 8, 4, 3};

		for (int i = 0; i < arr1.length - 1 ; i++){
            int tag ;
            if(arr1[i] > arr1[i+1]){
                tag = arr1[i];
                arr1[i] = arr1[i+1];
                arr1[i+1] = tag;
            }
		} 
	     System.out.println(Arrays.toString(arr1));

         for (int i = 0; i < arr1.length - 2 ; i++){
            int tag ;
            if(arr1[i] > arr1[i+1]){
                tag = arr1[i];
                arr1[i] = arr1[i+1];
                arr1[i+1] = tag;
            }
		} 
	    System.out.println(Arrays.toString(arr1));

        Main.sort();
	}

 
}

代码地址