TreeMap的原理和使用

package _03;

import java.util.Map;
import java.util.TreeMap;

public class _3_15TreeMap {

    public static void main(String[] args) {
//        一般也不用TreeMap，排序的时候多用TreeMap
//        TreeMap底层采用了红黑二叉树
//        Map treemap = new TreeMap<>();
//        treemap.put(1,"aa");
//        treemap.put(2,"bb");
//        treemap.put(3,"cc");

//        map的一种遍历方式
//        for( Integer key : treemap.keySet()){
//            System.out.println(key+","+treemap.get(key));
//        }
        //TreeMap按照 key自增的顺序进行排序

        Map treemap = new TreeMap<>();
        treemap.put(new Emp(1001,"wei",5000),"w");
        treemap.put(new Emp(1100,"li",4000),"l");
        treemap.put(new Emp(1200,"guan",6000),"g");

        for (Emp key:treemap.keySet()
             ) {
            System.out.println(key.name+key.Salary+key.id);
        }


//        HashMap和HashTable的区别
//        HashMap：线程不安全，效率高  允许key和value值为空
//        HashTable：线程安全，效率低， 不允许key和value值为空

        
    }


}

class Emp implements Comparable{

    int id;
    String name;
    double Salary;

    public Emp(int id, String name, double salary) {
        this.id = id;
        this.name = name;
        Salary = salary;
    }

    @Override
    public int compareTo(Emp o) {
//        负数对应小于，0对应等于，正数对应大于
        if(this.Salary>o.Salary){
            return 1;
        }else if(this.Salary < o.Salary){
            return -1;
        }else{
            if(this.id >o.id){
                return 1;
            }else if(this.id