42.9 TreeMap集合概述和特点

package com.itheima.d9_map_impl;
import com.itheima.d1_set.Apple;
import java.util.Comparator;
import java.util.Map;
import java.util.TreeMap;
public class TreeMapDemo3 {
    public static void main(String[] args) {
        // TreeMap 有序
        Map<Integer,String> maps1 = new TreeMap<>();
        maps1.put(13,"王麻子");
        maps1.put(1,"张三");
        maps1.put(3,"县长");
        System.out.println(maps1); //{1=张三, 3=县长, 13=王麻子}
        // TreeMap集合自带排序。可排序 不重复 （只要大小规则一样就可以认为重复） 无索引
        // 自带比较器
        Map<Apple,String> maps2 = new TreeMap<>(new Comparator<Apple>() {
            @Override
            public int compare(Apple o1, Apple o2) { //
                return Double.compare(o2.getPrice(),o1.getPrice()); // 根据价格降序
            }
        });
        maps2.put(new Apple("红富士","红色",9.9,500),"山东");
        maps2.put(new Apple("青苹果","绿色",15.9,300),"江西");
        maps2.put(new Apple("绿苹果","青色",29.9,400),"广州");
        maps2.put(new Apple("黄苹果","红色",9.8, 500),"深圳");
        System.out.println(maps2); //{Apple{name='青苹果', color='绿色', price=15.9, weight=300}=江西, Apple{name='绿苹果', color='青色', price=29.9, weight=400}=广州, Apple{name='红富士', color='红色', price=9.9, weight=500}=深圳}
        // 输出没有山东，覆盖了
    }
}