A HashMap is used to store key-value pairs. Internally, it uses hashing to store data and fetch data. In this tutorial, we will learn how to initialize a HashMap in Java. Using the put() method of HashMap The put() method takes a key and a value as parameters and adds the key-...
This example is a standard Java way to declare and initialize aHashMap. The result is a mutable map, and we can useCollections.unmodifiableMapto convert a mutable map to an immutable map. // normal way, mutable mapMap<String, String> map =newHashMap<>(); map.put("key1","value1");...
To directly initialize a HashMap in Java, you can use the put() method to add elements to the map.
Alternatively, theofEntries()method of the Map method accepts n key-value pairs and can initialize a HashMap of infinite elements. Example of initializing inline Java HashMap using MapofEntries()method. Map<String, String> ofEntries = Map.ofEntries( Map.entry("color","pink"), Map.entry("...
FileName:StaticMapExample.java importjava.util.HashMap; importjava.util.Map; publicclassStaticMapExample { // Define the static map as a class variable privatestaticMap<String,Integer> staticMap; // Static initialization block static{ // Instantiate the map and populate it with key-value pairs...
HashMap<String,Integer>details=newHashMap<>();details.put("keanu",23);details.put("max",24);details.put("john",53);names.addAll(details.keySet());//Adding multiple elements in ArrayList 3. Initialize ArrayList from Java 8 Stream
Java 9 introduced a factory method in the Set interface that is the most compact and straightforward way to create an immutable instance of Java HashSet inline. However, there are other ways available too. Please refer to ourGitHub Repositoryfor the complete source code of this tutorial....
In this tutorial, you will learn how to initialize an ArrayList in Java. There are several different ways to do this. Let's discuss them with examples. 1. Basic (Normal) Initialization One of the ways to initialize an ArrayList is to create it first and
How to reverse an ArrayList in Java? How to synchronize an ArrayList in Java? Loop through an ArrayList using an Iterator in Java Initialize HashSet in Java Initialize HashMap in Java How to initialize an array in JShell in Java 9? Check existence of an element in Java ArrayListKick...
import java.util.Map; class Main { private static final Map<Integer, String> map; static { map = new HashMap<>(); map.put(1, "one"); map.put(2, "two"); } public static void main(String[] args) { System.out.println(map); } } Download Run Code A good practice is to ensure...