java List 排序 Collections.sort() 对 List 排序
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//一个POJO例子class User { String name; String age; public User(String name,String age){ this.name=name; this.age=age; } public String getAge() { return age; } public void setAge(String age) { this.age = age; } public String getName() { return name; } public void setName(String name) { this.name = name; } }//具体的比较类,实现Comparator接口import java.util.Comparator;import java.util.List;import java.util.ArrayList;import java.util.Collections;public class ComparatorUser implements Comparator{ public int compare(Object arg0, Object arg1) { User user0=(User)arg0; User user1=(User)arg1; //首先比较年龄,如果年龄相同,则比较名字 int flag=user0.getAge().compareTo(user1.getAge()); if(flag==0){ return user0.getName().compareTo(user1.getName()); }else{ return flag; } } }//测试类public class SortTest { public static void main(String[] args){ List userlist=new ArrayList(); userlist.add(new User("dd","4")); userlist.add(new User("aa","1")); userlist.add(new User("ee","5")); userlist.add(new User("bb","2")); userlist.add(new User("ff","5")); userlist.add(new User("cc","3")); userlist.add(new User("gg","6")); ComparatorUser comparator=new ComparatorUser(); Collections.sort(userlist, comparator); for (int i=0;i<userlist.size();i++){ User user_temp=(User)userlist.get(i); System.out.println(user_temp.getAge()+","+user_temp.getName()); } }} //首先年龄排序,如果年龄相同,则按名字排序结果: 1, aa 2, bb 3, cc 4, dd 5, ee //注意:同样是5岁的人,则比较名字(ee,ff),然后排序 5, ff 6, gg