Mar 7, 2025 · In Java, HashMap is part of the Java Collections Framework and is found in the java.util package. It provides the basic implementation of the Map interface in Java. HashMap stores data in (key, value) pairs. Each key is associated with a value, and you can access the value by using the corresponding key.

Hash table based implementation of the Map interface. This implementation provides all of the optional map operations, and permits null values and the null key. (The HashMap class is roughly equivalent to Hashtable, except that it is unsynchronized and permits nulls.)

Keys and values in a HashMap are actually objects. In the examples above, we used objects of type "String". Remember that a String in Java is an object (not a primitive type). To use other types, such as int, you must specify an equivalent wrapper class: Integer.

Apr 22, 2025 · In this article, we will understand the internal workings of the HashMap in Java, also how the get() and put() method functions, how hashing is done, how key-value pairs are stored, and how the values are retrieved by keys.

Aug 6, 2023 · Learn the hashmap internal implementation analysis, collision resolution and Java 8 hashmap update. Java HashMap is a member of the Collections framework and stores key-value pairs. Each key is mapped to a single value, and duplicate keys are not allowed.

Feb 12, 2025 · HashMap is a part of the Java collection framework. It uses a technique called Hashing. It implements the map interface. It stores the data in the pair of Key and Value. HashMap contains an array of the nodes, and the node is represented as a class. It uses an array and LinkedList data structure internally for storing Key and Value.

Aug 9, 2024 · A HashMap is one of the most commonly used data structures in Java, and it's known for its efficiency. Data in a HashMap is stored in the form of key-value pairs. In this article, I will introduce you to HashMaps in Java.

The HashMap class provides the functionality of the hash table data structure in Java. In this tutorial, we will learn about the Java HashMap class and its various operations with the help of examples.

Jan 18, 2024 · HashMap in Java is a data structure that uses a hash table to store key-value pairs. Basic operations like put() , get() and delete() may be quickly performed using a HashMap, often in constant time.

Dec 5, 2024 · We can create HashMap using different ways, specific to the requirements. For example, we can create an empty HashMap containing no key-value pairs initially. Later, we can add the key-value pairs in this empty HashMap. Additionally, we can specify the initial load capacity and load factor for performance reasons discussed later in this article.