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. Â 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. Â 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. Â 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. Â 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]
