1.

public class DemoTreeMap3 {    public static void main(String[] args) {        System.out.println("------对hashMap按照key进行排序----------");        Map
      
        map   = new HashMap
       
        ();        map.put(new Car("凯迪拉克",50),"看iadilake1");        map.put(new Car("法拉利",100),"阿迪发送发的");        map.put(new Car("大众", 20), "迈腾");                Comparator
        
          c = new CarComparator();        Map
         
           map2   = new TreeMap
          
           (c);        map2.putAll(map);                Set
           
             set = map2.keySet(); for (Car car : set) { System.out.println(car.getPrice()+"--"+car.getType()); } System.out.println("------对hashMap按照value进行排序----------"); //对HashMap按照value进行排序 Map
            
              map3 = new HashMap
             
              (); map3.put("大众",new Car("凯迪拉克",50)); map3.put("法拉利",new Car("法拉利",100)); map3.put("福特",new Car("福特", 20)); //第一步：把待排序map集合的引用传递进入自定义比较器 //第二步：在自定义比较器中，加入成员变量，接收map集合的引用 Comparator
              
                compar = new CarComparator2(map3); Map
               
                 treeMap = new TreeMap
                
                 (compar); treeMap.putAll(map3); Collection
                 
                   cars = treeMap.values(); for (Car car : cars) { System.out.println(car.getPrice()+"--"+car.getType()); } }}
                 
                
               
              
             
            
           
          
         
        
       
      

import java.util.Comparator;public class CarComparator implements Comparator
      
       {    @Override    public int compare(Car o1, Car o2) {        return (int)(o1.getPrice()-o2.getPrice());    }}
      

public class CarComparator2 implements Comparator
      
        {    private Map
       
         map;    public CarComparator2(Map
        
          map3) {        this.map = map3;    }    @Override    public int compare(String key1, String key2) {        Car car1 = map.get(key1);        Car car2 = map.get(key2);        return (int) (car1.getPrice() - car2.getPrice());    }}