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What's the quickest way to remove an element from a Map by value in Java?
Currently I'm using:
DomainObj valueToRemove = new DomainObj(); String removalKey = null; for (Map.Entry<String, DomainObj> entry : map.entrySet()) { if (valueToRemove.equals(entry.getValue())) { removalKey = entry.getKey(); break; } } if (removalKey != null) { map.remove(removalKey); } 
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The Java HashMap remove() method removes the mapping from the hashmap associated with the specified key. The syntax of the remove() method is: hashmap. remove(Object key, Object value);
HashMap remove() Method in Java remove() is an inbuilt method of HashMap class and is used to remove the mapping of any particular key from the map. It basically removes the values for any particular key in the Map. Parameters: The method takes one parameter key whose mapping is to be removed from the Map.
Assuming your set contains the strings you want to remove, you can use the keySet method and map. keySet(). removeAll(keySet); . keySet returns a Set view of the keys contained in this map.
You should always use Iterator's remove() method to remove any mapping from the map while iterating over it to avoid any error.
The correct and fast one-liner would actually be:
while (map.values().remove(valueObject)); Kind of strange that most examples above assume the valueObject to be unique.
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