Java HashMap原理及实例解析

package collection;
  
import java.util.HashMap;
  
public class TestCollection {
  public static void main(String[] args) {
    HashMap<String,String> dictionary = new HashMap<>();
    dictionary.put("adc", "物理英雄");
    dictionary.put("apc", "魔法英雄");
    dictionary.put("t", "坦克");
     
    System.out.println(dictionary.get("t"));
  }
}

package collection;
 
import java.util.HashMap;
 
import charactor.Hero;
 
public class TestCollection {
  public static void main(String[] args) {
    HashMap<String,Hero> heroMap = new HashMap<String,Hero>();
     
    heroMap.put("gareen", new Hero("gareen1"));
    System.out.println(heroMap);
     
    //key为gareen已经有value了，再以gareen作为key放入数据，会导致原英雄，被覆盖
    //不会增加新的元素到Map中
    heroMap.put("gareen", new Hero("gareen2"));
    System.out.println(heroMap);
     
    //清空map
    heroMap.clear();
    Hero gareen = new Hero("gareen");
     
    //同一个对象可以作为值插入到map中，只要对应的key不一样
    heroMap.put("hero1", gareen);
    heroMap.put("hero2", gareen);
     
    System.out.println(heroMap);
     
  }
}