清除除两个键/值对之外的所有hashmap值

I have a HashMap with hundred of key/value pairs.

我有一个包含数百个键/值对的HashMap。

Now I have to delete all key/values except 2 key/value. I have use this way :

现在我必须删除除2键/值以外的所有键/值。我用这种方式:

if(map!=null){
     String search = map.get(Constants.search);
     String context = map.get(Constants.context);
     map = new HashMap<>();
     map.put(Constants.search,search);
     map.put(Constants.context,context);
}

But java 8 introduced removeIf() for these kind of condition. How can I solve this problem with removeIf() method ?

但java 8为这些条件引入了removeIf()。如何使用removeIf()方法解决此问题?

1 个解决方案

#1

You'll need to it like this :

你需要这样:

map.keySet()
   .removeIf(key -> !(key.equals(Constants.search) || key.equals(Constants.context)));

It will iterate over the keys and remove the ones for those the key is not one of or two required keys

它将迭代密钥并删除那些密钥不是一个或两个必需密钥的密钥

#1