Iterate Through Elements of LinkedHashSet in Java

07 Jan, 2021
The LinkedHashSet is an ordered version of HashSet that maintains a doubly-linked List across all elements. When the iteration order is needed to be maintained this class is used.
Example:
Input: 
["Geeks", "for", "Geeks"]


Output:
Geeks
for
Geeks
    
Input: 
[9, 4, 6, 2, 8]


Output:
9
4
6
2
8
Different Ways to Iterate LinkedHashSet Elements:
Using the for-each loopUsing iteratorsUsing JDK 1.8 streams
Using the for-each loop
Using iterators
Using JDK 1.8 streams
Method 1:  Using the for-each loop
Java
// Java Program to Iterate through linkedHashset// Using the for-each loop  import java.io.*;import java.util.LinkedHashSet;  class GFG {    public static void main(String[] args)    {          LinkedHashSet<String> gfg            = new LinkedHashSet<String>();          // Adding element to LinkedHashSet        gfg.add("Geeks");        gfg.add("for");        gfg.add("geeks");          // iterating LinkedHashSet using enhanced for loop        for (String itr : gfg) {            System.out.println(itr);        }    }}
Geeks
for
geeks
Method 2: Using iterators
Iterate through the elements of  LinkedHashSet using the iterator method.  We will use the hasNext() method and the next() method along with the while loop to iterate through LinkedHashSet elements.
Type Parameters:
E – the type of elements maintained by this set.
Syntax:
public Iterator<E> iterator()
Return: This method returns the element of LinkedHashSet in the same order as the input.
Java
// Java code to demonstrate // the iterating over LinkedHashSet // Using iterators    import java.io.*; import java.util.*;     class IteratingLinkedHashSet {         public static void main(String[] args)     {         // Instantiate an object of Set         // Since LinkedHashSet implements Set         // Set points to LinkedHashSet         Set<String> gfg = new LinkedHashSet<String>();             // Elements are added using add() method         gfg.add("Geek");         gfg.add("For");         gfg.add("Geeks");         gfg.add("Courses");         gfg.add("Interview Prep");         gfg.add("Doubt Classes");             // Iterating through the LinkedHashSet         Iterator itr = gfg.iterator();                 while (itr.hasNext()){              System.out.println( itr.next() );        }    }}
Geek
For
Geeks
Courses
Interview Prep
Doubt Classes
Method 3: Using JDK 1.8 streams
Iterate through the elements of LinkedHashSet using the forEach method. We will iterate through the entire content using Stream. The stream represents a sequence of objects from a source, which supports aggregate operations.
Syntax:
set.stream().forEach()
Return: Returns a sequential stream considering collection as its source.
Java
// Java code to demonstrate// the iterating over LinkedHashSet// Using JDK 1.8 streams  import java.io.*;import java.util.*;  class GFG {    public static void main(String[] args)    {          LinkedHashSet<Integer> gfg = new LinkedHashSet<Integer>();          // Elements are added using add() method        gfg.add(9);        gfg.add(7);        gfg.add(11);        gfg.add(43);        gfg.add(2);          // Using forEach Method using Stream.        gfg.stream().forEach(System.out::println);    }}
9
7
11
43
2
Time complexity: O(N), where N is no. of elements of LinkedHashSet.
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