package com.yonyou.test; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.List; public class Test {  public static void main(String[] args) {   Student zlj = new Student("丁晓宇", 21);   Student dxy = new Student("赵四", 22);   Student cjc = new Student("张三", 11);   Student lgc = new Student("刘武", 19);   List<Student> studentList = new ArrayList<Student>();   studentList.add(zlj);   studentList.add(dxy);   studentList.add(cjc);   studentList.add(lgc);   System.out.println("按照年齡排序：");   Collections.sort(studentList, new SortByAge());   for (Student student : studentList) {    System.out.println(student.getName() + " / " + student.getAge());   }   System.out.println(" ========= ");   System.out.println("按照姓名排序");   Collections.sort(studentList, new SortByName());   for (Student student : studentList) {    System.out.println(student.getName() + " / " + student.getAge());   }  } } class SortByAge implements Comparator {  public int compare(Object o1, Object o2) {   Student s1 = (Student) o1;   Student s2 = (Student) o2;   if (s1.getAge() > s2.getAge())    return 1;   else if (s1.getAge() == s2.getAge()) {    return 0;   }   return -1;  } } class SortByName implements Comparator {  public int compare(Object o1, Object o2) {   Student s1 = (Student) o1;   Student s2 = (Student) o2;   if(s1.getName().compareTo(s2.getName()) < 0)    return -1;   else if (s1.getName().compareTo(s2.getName()) > 0) {    return 1;   }   return 0;  } } class Student{  private int age;  private String name;  public int getAge() {   return age;  }  public void setAge(int age) {   this.age = age;  }  public String getName() {   return name;  }  public void setName(String name) {   this.name = name;  }  public Student(String name,int age) {   this.age = age;   this.name = name;  } }

public class Person{      String name;      int age;  public Person(String name,int age){      this.name = name;      this.age = age;  }  public int getAge() {      return age;  }  public void setAge(int age) {      this.age = age;  }  public String getName() {      return name;  }  public void setName(String name) {      this.name = name;  } }

// 实现Comparator接口,也就是定义排序规则,你几乎可以定义任何规则 package com.infoearth; import java.util.*; public class Mycomparator implements Comparator{     public int compare(Object o1,Object o2) {         Person p1=(Person)o1;         Person p2=(Person)o2;         if(p1.age<p2.age)            return 1;        else            return 0;        } }

package com.infoearth; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; public class ListSort {      public static void main(String[] args){          ArrayList list = new ArrayList();          list.add(new Person("lcl",28));          list.add(new Person("fx",23));          list.add(new Person("wqx",29));          Comparator comp = new Mycomparator();          Collections.sort(list,comp);           for(int i = 0;i<list.size();i++){              Person p = (Person)list.get(i);              System.out.println(p.getName());          }       } }