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public static void main(String[] args) {

    // map init

    Map<String, String> map = new HashMap<>();

    map.put("k", "v");

    /*=====处理函数只有单条语句=====*/

    map.forEach((k, v) -> System.out.println(k + v));

    /*=====处理函数有多个步骤=======*/

    map.forEach((k, v) -> {

      System.out.println(111);

      System.out.println(k + v);

    });

  }

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public static void main(String[] args) {

//      Map<String, Object> map = new HashMap<String, Object>();

        Map<String, Object> map = new LinkedHashMap<String, Object>();

        map.put("username","zhaokuo");

        map.put("password", "123456");

        map.put("email", "[email protected]");

        map.put("sex", "男");

        //第一种 用for循环的方式

        for (Map.Entry<String, Object> m :map.entrySet()) {

            System.out.println(m.getKey()+"\t"+m.getValue());

        }

        //利用迭代 （Iterator）

        Set set=map.entrySet();

        Iterator iterator=set.iterator();

        while(iterator.hasNext()){

                Map.Entry<String, Object> enter=(Entry<String, Object>) iterator.next();

                System.out.println(enter.getKey()+"\t"+enter.getValue());

        }

        //利用KeySet 迭代

        Iterator it = map.keySet().iterator();

        while(it.hasNext()){

             String key; 

           String value; 

           key=it.next().toString(); 

           value=(String) map.get(key); 

           System.out.println(key+"--"+value); 

        }

        //利用EnterySet迭代

        Iterator i=map.entrySet().iterator();    

        System.out.println( map.entrySet().size()); 

        String key;    

        String value; 

        while(i.hasNext()){ 

            Map.Entry entry = (Map.Entry)i.next();    

            key=entry.getKey().toString();    

            value=entry.getValue().toString();    

            System.out.println(key+"===="+value);         

        }

        System.out.println(getKeyByValue(map, "zhaokuo"));

    }

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//根据Value取Key

    public static String getKeyByValue(Map map, Object value) {

        String keys="";

        Iterator it = map.entrySet().iterator();

        while (it.hasNext()) {

            Map.Entry entry = (Entry) it.next();

            Object obj = entry.getValue();

            if (obj != null && obj.equals(value)) {

                keys=(String) entry.getKey();

            }

        }

        return keys;

        }