How to Initialize a Set in Java - Step by Step Examples

How to Initialize a Set in Java ?

Answer

To initialize a set in Java, you can use the HashSet class or other implementations of the Set interface such as LinkedHashSet and TreeSet.

✐ Examples

1 Initialize an Empty HashSet

In this example,

We use the HashSet class, which is a standard implementation of the Set interface in Java, to create a new, empty set.
We declare a variable named set1 and assign it the result of calling the new HashSet<>() constructor.
The new HashSet<>() constructor creates an empty hash set.
We then print the set1 to the standard output to verify its contents. An empty set in Java is represented as [].

Java Program

import java.util.HashSet;
import java.util.Set;

public class Main {
    public static void main(String[] args) {
        Set<String> set1 = new HashSet<>();
        System.out.println("Contents of set1: " + set1);
    }
}

Output

Contents of set1: []

2 Initialize a HashSet with Elements

In this example,

We use the HashSet class to create a new set and initialize it with elements.
We declare a variable named set2 and assign it the result of calling the new HashSet<>() constructor.
We add elements to set2 using the add method. For example, we add the strings "apple", "banana", and "cherry".
We then print the set2 to the standard output to verify its contents.

Java Program

import java.util.HashSet;
import java.util.Set;

public class Main {
    public static void main(String[] args) {
        Set<String> set2 = new HashSet<>();
        set2.add("apple");
        set2.add("banana");
        set2.add("cherry");
        System.out.println("Contents of set2: " + set2);
    }
}

Output

Contents of set2: [apple, banana, cherry]

Summary

In this tutorial, we learned How to Initialize a Set in Java language with well detailed examples.

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