java中Map根据Map的value取key

实例：<small>java代码</small>

class AAAA{

public static void main(String[] args) {
Map<String, Object> map = new LinkedHashMap<String, 
Object>();
map.put("username","zhaokuo");
map.put("password", "123456");
map.put("email", "zhaokuo719@163.com");
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"));
}

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();搜索
}
 
}
return keys;
}

}```