package com.jabberchina.test;    import java.util.ArrayList;  import java.util.Collections;  import java.util.Comparator;  import java.util.List;    public class SortTest {                        public static void main(String[] args) {          List
     
       lists = new ArrayList
      
       ();          List
        list = new ArrayList
       ();          List listB = new ArrayList();          lists.add("5");          lists.add("2");          lists.add("9");          //lists中的对象String 本身含有compareTo方法，所以可以直接调用sort方法，按自然顺序排序，即升序排序          Collections.sort(lists);                    A aa = new A();          aa.setName("aa");          aa.setOrder(1);          A bb = new A();          bb.setName("bb");          bb.setOrder(2);          list.add(bb);          list.add(aa);          //list中的对象A实现Comparable接口          Collections.sort(list);                    B ab = new B();          ab.setName("ab");          ab.setOrder("1");          B ba = new B();          ba.setName("ba");          ba.setOrder("2");          listB.add(ba);          listB.add(ab);          //根据Collections.sort重载方法来实现          Collections.sort(listB,new Comparator(){ @Override public int compare(B b1, B b2) { return b1.getOrder().compareTo(b2.getOrder()); } }); System.out.println(lists); System.out.println(list); System.out.println(listB); } } class A implements Comparable
       { private String name; private Integer order; public String getName() { return name; } public void setName(String name) { this.name = name; } public Integer getOrder() { return order; } public void setOrder(Integer order) { this.order = order; } @Override public String toString() { return "name is "+name+" order is "+order; } @Override public int compareTo(A a) { return this.order.compareTo(a.getOrder()); } } class B{ private String name; private String order; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getOrder() { return order; } public void setOrder(String order) { this.order = order; } @Override public String toString() { return "name is "+name+" order is "+order; } } 打印的结果为： [2, 5, 9] [name is aa order is 1, name is bb order is 2] [name is ab order is 1, name is ba order is 2]