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Oct 4, 2024 · Hierarchy of Map Interface in Java . Classes that implement the Map interface are depicted in the below media and described later as follows: 1. HashMap . HashMap is a part of Java’s collection since Java 1.2. It provides the basic implementation of the Map interface of Java. It stores the data in (Key, Value) pairs.
A Map is useful if you have to search, update or delete elements on the basis of a key. Java Map Hierarchy. There are two interfaces for implementing Map in java: Map and SortedMap, and three classes: HashMap, LinkedHashMap, and TreeMap. The hierarchy of Java Map is given below: A Map doesn't allow duplicate keys, but you can have duplicate values.
- size. int size() Returns the number of key-value mappings in this map. If the map contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.
- isEmpty. boolean isEmpty() Returns true if this map contains no key-value mappings. Returns: true if this map contains no key-value mappings.
- containsKey. boolean containsKey(Object key) Returns true if this map contains a mapping for the specified key. More formally, returns true if and only if this map contains a mapping for a key k such that (key==null ?
- containsValue. boolean containsValue(Object value) Returns true if this map maps one or more keys to the specified value. More formally, returns true if and only if this map contains at least one mapping to a value v such that (value==null ?
The Map Interface. A Map is an object that maps keys to values. A map cannot contain duplicate keys: Each key can map to at most one value. It models the mathematical function abstraction. The Map interface includes methods for basic operations (such as put, get, remove, containsKey, containsValue, size, and empty), bulk operations (such as ...
The Map interface includes the following methods: put(K, V) - Inserts the association of a key K and a value V into the map. If the key is already present, the new value replaces the old value. putAll() - Inserts all the entries from the specified map to this map. get(K) - Returns the value associated with the specified key K.
The Map interface maps unique keys to values. A key is an object that you use to retrieve a value at a later date. Given a key and a value, you can store the value in a Map object. After the value is stored, you can retrieve it by using its key. Several methods throw a NoSuchElementException when no items exist in the invoking map.
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Mar 10, 2024 · This Comprehensive Java Map Tutorial Covers how to Create, Initialize, and Iterate through Maps. You will also learn about Map Methods and Implementation Examples: You will get to know the basics of map interface, methods supported by map interface, and other specific terms related to map interface. Maps collection in Java is a collection that ...
