package cn.edu.zzu;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(){ 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; } 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; }}
         
        
运行结果:
[2, 34, 3434]
[name is aa order is 1, name is bb order is 2]
[name is ab order is 1, name is ba order is 2]
package cn.edu.zzu;import java.util.ArrayList;import java.util.Collections;import java.util.Comparator;import java.util.List;public class List元素排序 {    public static void main(String[] args) {        List
            
              list = new ArrayList
             
              ();        // 创建3个学生对象，年龄分别是20、19、21，并将他们依次放入List中        Student s1 = new Student();        s1.setAge(20);        Student s2 = new Student();        s2.setAge(19);        Student s3 = new Student();        s3.setAge(21);        list.add(s1);        list.add(s2);        list.add(s3);        System.out.println("排序前：" + list);        Collections.sort(list, new Comparator
              
               () {            /*             * int compare(Student o1, Student o2) 返回一个基本类型的整型， 返回负数表示：o1 小于o2，             * 返回0 表示：o1和o2相等， 返回正数表示：o1大于o2。             */            public int compare(Student o1, Student o2) {                // 按照学生的年龄进行升序排列                if (o1.getAge() > o2.getAge()) {                    return 1;                }                if (o1.getAge() == o2.getAge()) {                    return 0;                }                return -1;            }        });        System.out.println("排序后：" + list);    }}class Student {    private int age;    public int getAge() {        return age;    }    public void setAge(int age) {        this.age = age;    }    @Override    public String toString() {        return getAge() + "";    }}
              
             
            
排序前：[20, 19, 21]
排序后：[19, 20, 21]