• 通过键找值
  

  package com.baidu.demo;
  
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Set;
  //通过键找值
  public class Demo01 {
      public static void main(String[] args) {
          HashMap<String, String> map = new HashMap<>();
          map.put("一", "老大");
          map.put("二", "老二");
          map.put("三", "老三");
          //foreach循环遍历
          Set<String> keySet = map.keySet();
          for (String string : keySet) {
              System.out.println(string+"====="+map.get(string));
          }
          //iterator遍历
          Iterator<String> iterator = map.keySet().iterator();
          while (iterator.hasNext()) {
              String string = (String) iterator.next();
              System.out.println(string+"======"+map.get(string));
              
          }
          
      }
  }

   

• 通过键值对找值
  

  package com.baidu.demo;
  
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.Set;
  //通过键值对找值
  public class Demo01 {
      public static void main(String[] args) {
          HashMap<String, String> map = new HashMap<>();
          map.put("一", "老大");
          map.put("二", "老二");
          map.put("三", "老三");
          //foreach循环遍历
          Set<Entry<String, String>> entrySet = map.entrySet();
          for (Entry<String, String> entry : entrySet) {
              System.out.println(entry.getKey()+"===="+entry.getValue());
          }
          //iterator遍历
          Iterator<Entry<String, String>> iterator = entrySet.iterator();
          while (iterator.hasNext()) {
              Map.Entry<String,String> entry = (Map.Entry<String,String>) iterator.next();
              System.out.println(entry.getKey()+"====="+entry.getValue());
          }
      }
  }

   

hashmap的遍历