map的几种遍历方式和其他操作

    /*
    map遍历方式1
     */
    public static void  iterator1(){
          Iterator<Map.Entry<String,String >> iterator =map.entrySet().iterator();
          while (iterator.hasNext()){
              Map.Entry<String,String> next = iterator.next();
              String key=next.getKey();
              String value=next.getValue();
              System.out.print(key+ " " + value);
          }
    }

/*
 *map遍历方式2
 */
public static void iterator2(){
    for (Map.Entry<String,String> entry:map.entrySet()){
        String key=entry.getKey();
        String value=entry.getValue();
        System.out.print(key+ " " + value);
    }
}

```
        /*
         *map遍历方式3(根据key获取value)
         */
        public static void iterator3(){
            Iterator<String> iterator= map.keySet().iterator();
            while (iterator.hasNext()){
                String key=iterator.next();
                String value=map.get(key);
                System.out.print(key+ " " + value);
            }
        }

    /**
     * map遍历方式4(根据key获取value)
     */
    public static void iterator4(){
        for (Object o:map.keySet()){
            String key=o.toString();
            String value=map.get(key);
            System.out.print(key+ " " + value);
        }
    }

    /**
     * 根据value获取key
     */
     public static void byValue2Key(String value){
        StringBuilder sb=new StringBuilder();
         Iterator<String> iterator= map.keySet().iterator();
         while (iterator.hasNext()){
             String key=iterator.next();
             if (value.equals(map.get(key)));
             sb.append(key+ " ");
         }
     }

    /**
     * java如何遍历Map <String, ArrayList> map = new HashMap <String,ArrayList>();
     */
    public static void other(){
         System.out.println("java  遍历Map <String, ArrayList> map = new HashMap<String, ArrayList>();");
         Map<String, ArrayList> map = new HashMap<String, ArrayList>();
         Set<String> keys = map.keySet();
         Iterator<String> iterator = keys.iterator();
         while (iterator.hasNext()) {
             String key = iterator.next();
             ArrayList arrayList = map.get(key);
             for (Object o : arrayList) {
                 System.out.println(o);
             }

         }
     }