What does put return in HashMap?

put(K key, V value) method This method is used to set the value with the corresponding key in HashMap. It inserts the entry(Key-Value) in the hashmap. If the HashMap already contained the key, then the old value is replaced by a new Value. It returns null if there is no value presented in the hashmap for the given key.

Does put in HashMap replace old value?

2 Answers. Yes. If a mapping to the specified key already exists, the old value will be replaced (and returned). See Hashtable.

What method return the value associated with key?

The get(Object key) method is used to return the value to which the specified key is mapped, or null if this map contains no mapping for the key.

What does HashMap keySet return?

HashMap. keySet() method in Java is used to create a set out of the key elements contained in the hash map. It basically returns a set view of the keys or we can create a new set and store the key elements in them.

What happens when you put a key in a HashMap that already exists?

put() method of HashMap is used to insert a mapping into a map. This means we can insert a specific key and the value it is mapping to into a particular map. If an existing key is passed then the previous value gets replaced by the new value.

What is the return type of HashMap?

HashMap get() Method in Java util. HashMap. get() method of HashMap class is used to retrieve or fetch the value mapped by a particular key mentioned in the parameter. It returns NULL when the map contains no such mapping for the key.

What does HashMap get return if key not found?

If the key is not present in the map, get() returns null. The get() method returns the value almost instantly, even if the map contains 100 million key/value pairs. Fast performance is the reason maps are great when you have a lot of data to work through.

What is return type of values method in map?

Map Values() method returns the Collection view of the values contained in this map. The collection is backed by the map, so changes to the map are reflected in the collection, and vice-versa.

What is the return type of put in a hashmap?

According to java documentation return type of put is “type of value”. for example if declaration like this. HashMap mymap = new HashMap<>(); then return type will be String. and return value. if key exists in map ( you have set some value already with that key ) then you will get previous value.

What is the use of HashMap PUT() method in Java?

HashMap put () Method in Java. The java.util.HashMap.put () method of HashMap is used to insert a mapping into a map. This means we can insert a specific key and the value it is mapping to into a particular map. If an existing key is passed then the previous value gets replaced by the new value. If a new pair is passed, then

What happens when a hashmap key is passed to another HashMap?

If an existing key is passed then the previous value gets replaced by the new value. If a new pair is passed, then the pair gets inserted as a whole. Parameters: The method takes two parameters, both are of the Object type of the HashMap.

What is the return type of put method in map?

The method put has a return type same with the value: The method associates the specified value with the specified key in this map. If the map previously contained a mapping for the key, the old value is replaced. It returns the previous value associated with key, or null if there was no mapping for key .