An array is a collection of items stored at contiguous memory locations. An array can contain primitives data types as well as objects of a class depending on the definition of the array. Whereas LinkedHashSet contains only unique elements and they are stored in the same order in which they are inserted.
Examples:
Input: arr = {"A", "B", "C", "D", "A"}
Output: LinkedHashSet = {"A", "B", "C", "D"}
LinkedHashSet does not contain repeated elements.
Input: arr = {1, 3, 5, 3, 1}
Output: LinkedHashset = {1, 3, 5}
There are several ways using which we can convert an array to an object of the LinkedHashSet in Java as given below:
1. Using the asList method and LinkedHashSet constructor
- The LinkedHashSet class provides a constructor that accepts a collection object.
- But to use that, we need to convert the array to a List using the asList method of the Arrays class.
Java
// Java program to convert an array to LinkedHashSet import java.util.Arrays;import java.util.LinkedHashSet;import java.util.Set; public class ArrayToLinkedHashSet { public static void main(String[] args) { // array of string String[] names = { "John", "Devid", "Smith", "Joe", "Stark" }; // First convert the name array to List and then // use the LinkedHashSet constructor to convert // array to linkedhasset Set<String> linkedhasset_name = new LinkedHashSet<String>(Arrays.asList(names)); System.out.println( "LinkedHashSet contains element: " + linkedhasset_name); }} |
Output
LinkedHashSet contains element: [John, Devid, Smith, Joe, Stark]
2. Using the asList method and addAll method
- Similar to the previous approach, we will first convert an array to a List
- But this time instead of using the constructor, we will use addAll method to add elements from the array to a linked hash set.
Java
// Java program to convert an array to LinkedHashSet import java.util.Arrays;import java.util.LinkedHashSet;import java.util.Set; public class ArrayToLinkedHashSet { public static void main(String[] args) { String[] names = {"John", "Devid", "Smith", "Joe", "Stark"}; //create new empty LinkedHashSet object to store array element Set<String> linkhasset_name = new LinkedHashSet<String>(); //add all elements of list to LinkedHashSet linkhasset_name.addAll( Arrays.asList(names) ); System.out.println("LinkedHashSet contains: " + linkhasset_name); }} |
Output
LinkedHashSet contains: [John, Devid, Smith, Joe, Stark]
3. Using Java 8 Stream API:
- Similar to HashSet, you can also use toCollection() method of Collectors class to convert a Stream to LinkedHashSet.
- First, convert array to stream then convert the stream to LinkedHashSet using collection stream which only works in java 8 version.
collect( Collectors.toCollection( LinkedHashSet::new ) );
Java
// Java program to convert an array to LinkedHashSet import java.io.*; import java.util.ArrayList; import java.util.LinkedHashSet;import java.util.*; import java.util.stream.*;import java.util.Set; public class ArrayToLinkedHashSet { public static void main(String[] args) { String[] names = {"John", "Devid", "Smith", "Joe", "Stark"}; //create new empty LinkedHashSet object Set<String> linkhasset_name = new LinkedHashSet<String>(); //add all elements of list to LinkedHashSet linkhasset_name = Arrays.stream(names).collect( Collectors.toCollection( LinkedHashSet::new ) ); System.out.println("LinkedHashSet contains: " + linkhasset_name); }} |
Output
LinkedHashSet contains: [John, Devid, Smith, Joe, Stark]
4. Using a loop or brute force
- We can iterate through all the elements of the array using a for loop and add elements to the LinkedHashSet object one by one as given below.
Java
// Java program to convert an array to LinkedHashSet import java.io.*; import java.util.ArrayList; import java.util.LinkedHashSet;import java.util.*; import java.util.Set; public class ArrayToLinkedHashSet { public static void main(String[] args) { String[] names = {"John", "Devid", "Smith", "Joe", "Stark"}; //create new empty LinkedHashSet object Set<String> linkhasset_name = new LinkedHashSet<String>(); //iterate an array and add elements one by one to the linkedhasset for(String name : names){ linkhasset_name.add(name); } System.out.println("LinkedHashSet contains: " + linkhasset_name); }} |
Output
LinkedHashSet contains: [John, Devid, Smith, Joe, Stark]