Java Program to Get the First Element from LinkedHashSet

24 Dec, 2021
LinkedHashSet is an implementation of Set Abstract Data Type (ADT). It extends from the HashSet class which in-turn implements Set Interface. The difference between the LinkedHashSet and HashSet is the property of maintaining the element ordering. LinkedList is just a container holding sequence of elements. By definition, Set should not contain duplicate elements.  This property need not hold good for the LinkedList ADT. When elements should be duplicated and the order has to be maintained, one should use LinkedHashSet.
Methods: 
There are basically three standard ways to get an element from LinkedHashSet without changing it to a different data structure.
Converting it to an array or ListUsing IteratorsUsing Streams 
Converting it to an array or List
Using Iterators
Using Streams 
Implementation: Getting the First Element from LinkedHashSet
Method 1: By converting it to an array or List
Example
Java
// Java Program to Get the First Element from LinkedHashSet// by converting it to an array or List// Array is demonstrated below so do with List // Importing generic java packagesimport java.io.*;import java.lang.*;import java.util.*; // Classpublic class GFG {    // Main driver method    public static void main(String[] args)        throws java.lang.Exception    {        // Creating a LinkedHashMap object        // Declaring object of Integer type        LinkedHashSet<Integer> hashSet            = new LinkedHashSet<Integer>();         // Adding elements to LinkedHashMap        hashSet.add(2);        hashSet.add(1);        hashSet.add(4);        hashSet.add(6);        hashSet.add(8);         // Condition check using isEmpty() method which        // holds         // True till there is a single element in an object        // is remaining False, when there is no object left        // or if initially there was no element added        if (!hashSet.isEmpty()) {            // Converting the above Map to an array            Integer arr[] = new Integer[hashSet.size()];            arr = hashSet.toArray(arr);             // Accessing the first element by passing 0            // as an argument which by default            // accesses and prints out first element            System.out.println("First element: " + arr[0]);        }    }}
First element: 2
Method 2: Using Iterators
 Example 
Java
// Java Program to Get the First Element from LinkedHashSet// Using Iterators // Importing generic java packagesimport java.util.*;import java.lang.*;import java.io.*; // Classpublic class GFG {    // Main driver method    public static void main(String[] args)        throws java.lang.Exception    {        // Creating a LinkedHashMap        LinkedHashSet<Integer> hashSet            = new LinkedHashSet<Integer>();         // Adding elements to LinkedHashMap        hashSet.add(1);        hashSet.add(2);        hashSet.add(3);        hashSet.add(4);        hashSet.add(5);         // Iterator over LinkedHashMap        Iterator<Integer> iter = hashSet.iterator();         if (iter != null && iter.hasNext()) {            // Display the first element of Map using next()            // ethod            System.out.println(                "First element in LinkedHashSet: "                + iter.next());        }    }}
First element in LinkedHashSet: 1
Method 3: Using Streams 
Example: 
Java
// Java Program to Get the First Element from LinkedHashSet// Using Streams // Importing generic java packagesimport java.util.*;import java.lang.*;import java.io.*; // Classclass GFG {       // Main driver method    public static void main(String[] args) throws java.lang.Exception    {        // Creating a LinkedHashMap        LinkedHashSet<Integer> hashSet            = new LinkedHashSet<Integer>();         // Adding elements to LinkedHashMap        hashSet.add(1);        hashSet.add(2);        hashSet.add(3);        hashSet.add(4);        hashSet.add(5);         // Checking whether Map is empty or not        if (hashSet.size() == 0)             // Display message            System.out.println("The Set is Empty!");        else {            // Using stream() through findFirst() method            // over the elements of LinkedHashMap            int first = hashSet.stream().findFirst().get();             // Printing the first element of LinkedHashMap            System.out.println(                "First element in LinkedHashSet: " + first);        }    }}
First element in LinkedHashSet: 1
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