TreeMap

package com.atguigu.java;
import org.junit.Test;
import java.util.Comparator;
import java.util.Iterator;
import java.util.Set;
import java.util.TreeMap;
/**
 * @author Dxkstart
 * @create 2021-05-23 18:29
 */
public class TreeMapTest {
    //向TreeMap中添加key-value，要求key必须是由同一个类创建的对象
    //因为要按照key进行排序：自然排序 、 定制排序
    //自然排序
    @Test
    public void test1(){
        TreeMap map = new TreeMap();
        Person p1 = new Person("Tom", 12);
        Person p2 = new Person("Jerry", 19);
        Person p3 = new Person("Jack", 20);
        Person p4 = new Person("Rose", 18);
        map.put(p1,89);
        map.put(p2,79);
        map.put(p3,90);
        map.put(p4,98);
        //遍历
        Set set = map.entrySet();
        Iterator iterator = set.iterator();
        while(iterator.hasNext()){
            System.out.println(iterator.next());
        }
    }
    //定制排序 --->按年龄排序
    @Test
    public void test2(){
        TreeMap map = new TreeMap(new Comparator() {
            @Override
            public int compare(Object o1, Object o2) {
                if(o1 instanceof Person && o2 instanceof Person){
                    Person p1 =(Person)o1;
                    Person p2 =(Person)o2;
                    return Integer.compare(p1.getAge(),p2.getAge());
                }
                throw new RuntimeException("输入的类型不匹配！");
            }
        });
        Person p1 = new Person("Tom", 12);
        Person p2 = new Person("Jerry", 19);
        Person p3 = new Person("Jack", 20);
        Person p4 = new Person("Rose", 18);
        map.put(p1,89);
        map.put(p2,79);
        map.put(p3,90);
        map.put(p4,98);
        //遍历
        Set set = map.entrySet();
        Iterator iterator = set.iterator();
        while(iterator.hasNext()){
            System.out.println(iterator.next());
        }
    }
}