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Iterate Through Elements of LinkedHashSet in Java
  • Last Updated : 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:

  1. Using the for-each loop
  2. Using iterators
  3. Using JDK 1.8 streams

Method 1:  Using the for-each loop

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// 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);
        }
    }
}

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Output



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.

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// 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() );
        }
    }
}

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Output

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

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// 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);
    }
}

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Output

9
7
11
43
2

Time complexity: O(N), where N is no. of elements of LinkedHashSet.

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