作业题,不会做,请教 - 黑马程序员技术交流社区

package cn.liweidan.test1;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
/**
* 把集合中存储多个Person对象,Person有姓名和年龄,找出年龄最大的
*
* @author Weidan
*
*/
public class Demo04 {
public static void main(String[] args) {
//创建对象
Person p1 = new Person("张三",20);
Person p2 = new Person("李四",20);
Person p3 = new Person("王五",80);
//创建容器
List<Person> list = new ArrayList<>();
list.add(p1);
list.add(p2);
list.add(p3);
//按照排序类进行排序年龄最大的会被排在最后一个元素
Collections.sort(list,new PaiXu());
//取出最后一个元素输出
Person p = list.get(list.size()-1);
System.out.println(p.toString());
}
}
/**
* Person类包含名字和年龄
* @author Weidan
*
*/
class Person {
private String name;
private int age;
public Person() {
// TODO Auto-generated constructor stub
}
public Person(String name, int age) {
super();
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "Person [name=" + name + ", age=" + age + "]";
}
}
/**
* 排序类
* 先按照年龄排列再按照名字排列
* @author Weidan
*
*/
class PaiXu implements Comparator<Person> {
@Override
public int compare(Person o1, Person o2) {
if(o1.getAge()<o2.getAge()){
return -1;
}else if(o1.getAge()>o2.getAge()){
return 1;
}else{
if(0!=o1.getName().compareTo(o2.getName())){
return -1;
}else if(o1.getName().compareTo(o2.getName())>0) {
return 1;
}else{
return 0;
}
}
}
}

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