java List 排序 Collections.sort() 对 List 排序
java.util.Comparator 接口。要实现里面的函数
int compare(Object o1, Object 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。
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
"\`java
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
http://www.blogjava.net/zygcs/archive/2008/01/17/176032.html
http://muscle-liu.iteye.com/blog/157261