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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.
- HashMap
Java HashMap. Java HashMap class implements the Map...
- HashMap
- Creating Map Objects
- Hierarchy of Map Interface in Java
- Performing Operations Using Map Interface and Hashmap Class
- FAQs in Java Map Interface
Since Map is an interface, objects cannot be created of the type map. We always need a class that extends this map in order to create an object. And also, after the introduction of Genericsin Java 1.5, it is possible to restrict the type of object that can be stored in the Map. Syntax:Defining Type-safe Map
Classes that implement the Map interface are depicted in the below media and described later as follows:
Since Map is an interface, it can be used only with a class that implements this interface. Now, let’s see how to perform a few frequently used operations on a Map using the widely used HashMap class. And also, after the introduction of Genericsin Java 1.5, it is possible to restrict the type of object that can be stored in the map.
- Overview of Map Collection. A Map is an object that maps keys to values, or is a collection of attribute-value pairs. It models the function abstraction in mathematics.
- Implementations of Map. In the inheritance tree of the Map interface, there are several implementations but only 3 major, common, and general purpose implementations - they are HashMap and LinkedHashMap and TreeMap.
- Creating a new Map. Creating a HashMap: Always use interface type (Map), generics and diamond operator to declare a new map. The following code creates a HashMap
- Performing Basic Operations on a Map. The basic operations of a Map are association (put), lookup (get), checking (containsKey and containsValue), modification (remove and replace) and cardinality (size and isEmpty).
Learn how to use the Map interface to create and manipulate key-value pairs in Java. See examples of basic and bulk operations, collection views, and JDK 8 aggregate operations.
Learn how to use the Map interface of the Java collections framework, which provides the functionality of the map data structure. See examples of classes that implement Map, such as HashMap and TreeMap, and their methods.
Learn about the Map interface in Java, which defines a collection of key-value pairs. See the methods, parameters, exceptions, and examples of using Map and its subinterfaces and implementing classes.
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Sep 21, 2020 · Learn how to use the Java Map interface to store and retrieve key-value pairs. See examples of different Map implementations, generic types, null keys and values, and functional operations.
