The Java HashMap merge() method is used to insert a new (key,value) pair into the HashMap or to modify value for an already existing key. Syntax of merge() method merge(K key, V value, BiFunction<? super V,? super V,? extends V> remappingFunction) The parameters are- key– Key with which the resulting…
The Java HashMap computeIfAbsent() method is used to compute a new value for the specified key, if the specified key doesn’t already exist or key exists but mapped to null, in the HashMap. Syntax of computeIfAbsent() method computeIfAbsent(K key, Function<? super K,? extends V> mappingFunction) The parameters are- key– Key…
The Java HashMap computeIfPresent() method is used to compute a new value for the specified key if key already exists (and non-null) in the HashMap. Syntax of computeIfPresent() method computeIfPresent(K key, BiFunction<? super K,? super V,? extends V> remappingFunction) The parameters are- key– Key with which the computed value has…
The Java HashMap compute() method is used to compute a new value for the specified key. Syntax of compute() method compute(K key, BiFunction<? super K,? super V,? extends V> remappingFunction) The parameters are- key– Key with which the computed value has to be mapped. remappingFunction– It is an expression of…
In this tutorial you will see how to use putIfAbsent() method in Java HashMap. The putIfAbsent() method inserts the specified value if the passed key is not already present in the HashMap or the key is null. Using this method gives you an option to check if key is already…
HashMap internal implementation in Java or how does HashMap work internally in Java is a very important interview question. Some of the important points that you should know are- Where does HashMap store its elements internally? What is the term “bucket” in HashMap? What is hashing concept and how does…
HashMap in Java calculates hash based on the key of the inserted (key, value) pair and store its elements according to that. So essentially HashMap is an unordered collection but you may come across a scenario when you want to sort HashMap in Java. Sorting on HashMap can be done…
In this post we’ll see different ways to iterate a Map or HashMap in Java. One thing you should know is you can’t directly loop a Map in Java (except when you use forEach statement). There are methods that return a “collection view” of the Map using that view you…
HashMap in Java is the HashTable implementation of the Map interface and it is part of the Java Collections framework. HashMap class in Java extends AbstractMap class and implements Map, Cloneable and Serializable inerfaces. HashMap stores its elements as (key, value) pairs and to get a value you will need…
In the post ArrayList Internal Implementation in Java we have already seen the internal implementation details of one of the implementation of the List interface – ArrayList. In this post we’ll see LinkedList internal implementation in Java which is another implementation of the List interface Questions that may come up…
