HashMap集合排序方法

 import java.util.*;
  
  public class Main{
      public static void main(String[] args){
          Map<String, String> map = new HashMap<String, String>();    //构建键值对为<String, String>的Map集合
          map.put("a", "aaa");
          map.put("b", "bbb");
          map.put("c", "ccc");
      
         Set<Map.Entry<String, String>> entrySet = map.entrySet();    //先得到map集合的所有"映射"的Set集合,这里规范每个映射的类型为Map.Entry<K, V>
         Iterator<Map.Entry<String, String>> iter = entrySet.iterator();    //再得到entrySet集合的迭代器,Map.Entry<K, V>为迭代元素的类型
         while(iter.hasNext()){
             Map.Entry<String, String> item = iter.next();
             String key = item.getKey();
             String value = item.getValue();
             System.out.println("key:" + key + "-->value:" + value);
         }
        /*
         for(Map.Entry<String, String> item: entrySet){
             String key = item.getKey();
             String value = item.getValue();
             System.out.println("key:" + key + "-->value:" + value);
            }
         */
    }
 }
 

 运行结果
 key:b-->value:bbb
 key:c-->value:ccc
 key:a-->value:aaa

import java.util.*;
   
  public class Main{
      public static void main(String[] args){
          Map<String, String> map = new HashMap<String, String>();    //构建键值对为<String, String>的Map集合
         map.put("a", "aaa");
         map.put("b", "bbb");
          map.put("c", "ccc");
         
        Set<String> keySet = map.keySet();    //先获取map集合的所有键的Set集合
         Iterator<String> iter = keySet.iterator();    //再得到keySet集合的迭代器
         while(iter.hasNext()){
             String key = iter.next();
             String value = map.get(key);
             System.out.println("key:" + key + "-->value:" + value);
         }
         /*
        for(String key: keySet){
                     String value = map.get(key);
                    System.out.println("key:" + key + "-->value:" + value);
                 }
                 */
       }
 }

 运行结果
 key:b-->value:bbb
 key:c-->value:ccc
 key:a-->value:aaa
```

import java.util.*;
  
  public class Main{``
      public static void main(String[] args){
          Map<String, String> map = new HashMap<String, String>();    //先构造键值对为<String, String>的Map集合
          map.put("a", "aaa");
          map.put("b", "bbb");
          map.put("c", "ccc");
      
         Collection<String> collection = map.values();    //再得到map集合的所有value的Collection集合
         System.out.println(collection);
     }
 }
 
 
  // 运行结果
  // [bbb, ccc, aaa]