Java实现冒泡(沉底)排序

两种for循环条件不一样，一种是冒泡一种是沉底，排序的思想都是两两比较；

注意看Bubble我注释的代码,自己Debug理解一下

package com.apesblog.sort.bubble;

public class Bubble {

    //初始a[]={ 3, 2, 1 };
    //i = 0;
        //j = 2;a->312
        //j = 1;a->132
        //j = 0;结束循环;
    //i = 1;
        //j = 2;a->123
        //j = 1;结束循环;
    //i = 2;结束循环; 
    public static void sortUp(Comparable[] a) {
        for (int i = 0; i < a.length - 1; i++) {
            for (int j = a.length - 1; j > i; j--) {
                if (greater(a[j - 1], a[j])) {
                    exch(a, j - 1, j);
                }
            }
        }
    }
    
    //初始a[]={ 3, 2, 1 };
    //i = 2;
        //j = 0;a->231
        //j = 1;a->213
        //j = 2;结束循环;
    //i = 1;
        //j = 0;a->123
        //j = 1;结束循环;
    //i = 0;结束循环; 
    public static void sortDown(Comparable[] a) {
      for (int i = a.length - 1; i > 0; i--) {
          for (int j = 0; j < i; j++) {
              if (greater(a[j], a[j + 1])) {
                  exch(a, j, j + 1);
              }
          }
      }    
  }

    private static boolean greater(Comparable i, Comparable j) {
        return i.compareTo(j) > 0;

    }

    private static void exch(Comparable[] a, int i, int j) {
        Comparable t = a[i];
        a[i] = a[j];
        a[j] = t;
    }

}

测试类如下：

package com.apesblog.sort.bubble;

import java.util.Arrays;

public class Test {

    public static void main(String[] args) {
        Integer[] a = { 3, 2, 1 };
        Bubble.sortUp(a);
        System.out.println("冒泡：" + Arrays.toString(a));
        Integer[] aa = { 3, 2, 1 };
        Bubble.sortDown(aa);
        System.out.println("沉底：" + Arrays.toString(aa));
package com.apesblog.sort.bubble;

import java.util.Arrays;

public class Test {

    public static void main(String[] args) {
        Integer[] a = { 4, 5, 6, 3, 2, 1 };
        Bubble.sortUp(a);
        System.out.println("冒泡：" + Arrays.toString(a));
        String[] s = { "d", "e", "f", "c", "b", "a" };
        Bubble.sortUp(s);
        System.out.println("冒泡：" + Arrays.toString(s));

        Integer[] aa = { 4, 5, 6, 3, 2, 1 };
        Bubble.sortDown(aa);
        System.out.println("沉底：" + Arrays.toString(aa));
        String[] ss = { "d", "e", "f", "c", "b", "a" };
        Bubble.sortDown(ss);
        System.out.println("沉底：" + Arrays.toString(ss));

    }

}