Map集合的获取功能

• V get(Object Key)：根据键获取值

  package com.gather.map;
  //Map集合的获取功能
  import java.util.HashMap;
  import java.util.Map;
  public class MapDemo03 {
      public static void main(String[] args) {
          Map<String,String> map=new HashMap<String,String>();
          map.put("张无忌","赵敏");
          map.put("郭靖","黄蓉");
          map.put("杨过","小龙女");
          //V get(Object key)：根据键获取值
          System.out.println(map.get("张无忌"));
      }
  }
  

• Set keySet()：获取所有键的集合

  package com.gather.map;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Set;
  public class MapDemo03 {
      public static void main(String[] args) {
          //创建集合对象
          Map<String,String> map=new HashMap<String,String>();
          map.put("张无忌","赵敏");
          map.put("郭靖","黄蓉");
          map.put("杨过","小龙女");
          //Set<K> keySet()：获取所有键的集合
          Set<String> keySet = map.keySet();
          for (String key:keySet){
              System.out.println(key);
          }
      }
  }
  

• Collection values()：获取所有值的集合

  package com.gather.map;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.Map;
  public class MapDemo03 {
      public static void main(String[] args) {
          Map<String,String> map=new HashMap<String,String>();
          map.put("张无忌","赵敏");
          map.put("郭靖","黄蓉");
          map.put("杨过","小龙女");
          //Collection<V> values()：获取所有值的集合
          Collection<String> values = map.values();
          for (String value:values){
              System.out.println(value);
          }
      }
  }