How to convert array to Set/HashSet

In Previous post we have learn how to convert Hashset to Array. In this post we will learn how to convert array to set . Array store data in contiguous memory locations and allow duplicate element to store. Set in java allow unique element only. Here we will discuss following ways for convert array to set in java.

  1. Using Arrays.asList() method
  2. Using Collections.AddAll() Method
  3. Using Add() Method

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1. Using Arrays.asList() method

We will pass array as argument in hashset and it will create hashset from array with the help of Arrays.AsList() method.

import java.util.Arrays;
import java.util.HashSet;

public class ArrayToSet {
	
	public static void main(String[] args) {
    	String [] arr = {"java","php","android","angularjs","spring"}; 
    	
    	//Constructs a new set containing the elements
    	//in the specified collection
    	HashSet<String> hashSet = new HashSet<>( Arrays.asList( arr ));
    	
    	//print hashset
    	System.out.println("hashset is ="+ hashSet);
    	
	}

}

Output :

hashset is =[spring, java, android, php, angularjs]

2. Using Collections.AddAll() Method

Here , We will learn java program of convert array to set with help of collections.AddAll() method.

  • Create an array to be convert
  • Create an empty HashSet
  • Add the element of array to hashset by passing  array and hashset as argument in collections.AddAll() method .
import java.util.Collections;
import java.util.HashSet;

public class ArrayToSet2 {
	
	public static void main(String[] args) {
		
    	String [] arr = {"java","php","android","angularjs","spring"}; 
    	
    	//Constructs a new set containing the 
    	//elements in the specified collection
    	HashSet<String> hashSet = new HashSet<String>();
		
    	//Adds all of the specified elements
    	//to the specified collection
    	Collections.addAll(hashSet, arr);
    	
    	//print hashset
    	System.out.println("hashset is ="+ hashSet);
    	
	}

}

Output:

hashset is =[spring, java, android, php, angularjs]

3. Using Add() Method

In this method we will convert array to set by iterating element of array and one by one add to hashset using add() method .

import java.util.HashSet;

public class ArrayToSet2 {
	
	public static void main(String[] args) {
		
    	String [] arr = {"java","php","android","angularjs","spring"}; 
    	
    	//Constructs a new set containing the 
    	//elements in the specified collection
    	HashSet<String> hashSet = new HashSet<String>();
		
    	for (String element : arr) {
			hashSet.add(element);
		}
    	
    	//print hashset
    	System.out.println("hashset is ="+ hashSet);
    	
	}

}

Output :

hashset is =[spring, java, android, php, angularjs]

In this tutorial we have learn java program how to convert array to set in java. You can learn also how to convert HashSet to array

Reference :

A Guide To HashSet                                                                                                          Java Doc – Hashset

 

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