Java LinkedList iterator() Method

Description

The Java LinkedList iterator() method returns an iterator over the elements in this list in proper sequence. The iterator is fail-fast means after creation of iterator, any structural modification done to linkedList object without using iterator.add() or remove() method will lead to ConcurrentModificationException.

Declaration

Following is the declaration for java.util.LinkedList.iterator() method

public Iterator<E> iterator()

Parameters

NA

Return Value

This method returns an iterator over the elements in this list in proper sequence.

Exception

NA

Getting Iterator to Iterate a LinkedList of Integers Example

The following example shows the usage of Java LinkedList iterator() method. We're creating a LinkedList of Integers. We're adding couple of Integers to the LinkedList object using add() method calls per element and using iterator() method, we're iterating the list and print all the elements.

package com.tutorialspoint;

import java.util.LinkedList;
import java.util.Iterator;

public class LinkedListDemo {
   public static void main(String[] args) {
      
      // create an empty linked list 
      LinkedList<Integer> linkedList = new LinkedList<>();

      // use add() method to add elements in the linkedList
      linkedList.add(0);
      linkedList.add(1);
      linkedList.add(2);
      linkedList.add(3);
      linkedList.add(4);
      linkedList.add(5);
      linkedList.add(6);
	  
      Iterator<Integer> iterator = linkedList.iterator();
      iterator.forEachRemaining(i -> System.out.println(i));
   }
}

Let us compile and run the above program, this will produce the following result −

0
1
2
3
4
5
6

Getting Iterator to Iterate a LinkedList of Strings Example

The following example shows the usage of Java LinkedList iterator() method. We're creating a LinkedList of Strings. We're adding couple of Strings to the LinkedList object using add() method calls per element and using iterator() method, we're iterating the list and print all the elements.

package com.tutorialspoint;

import java.util.LinkedList;
import java.util.Iterator;

public class LinkedListDemo {
   public static void main(String[] args) {
      
      // create an empty linked list
      LinkedList<String> linkedList = new LinkedList<>();

      // use add() method to add elements in the linkedList
      linkedList.add("A");
      linkedList.add("B");
      linkedList.add("C");
	  
      Iterator<String> iterator = linkedList.iterator();
      iterator.forEachRemaining(i -> System.out.println(i));
   }
}

Let us compile and run the above program, this will produce the following result −

A
B
C

Getting Iterator to Iterate a LinkedList of Objects Example

The following example shows the usage of Java LinkedList iterator() method. We're creating a LinkedList of Student objects. We're adding couple of Student objects to the LinkedList object using add() method calls per element and using iterator() method, we're iterating the list and print all the elements.

package com.tutorialspoint;

import java.util.LinkedList;
import java.util.Iterator;

public class LinkedListDemo {
   public static void main(String[] args) {

      // create an empty linkedList
      LinkedList<Student> linkedList = new LinkedList<>();

      // use add() method to add elements in the linkedList
      linkedList.add(new Student(1, "Julie"));
      linkedList.add(new Student(2, "Robert"));
      linkedList.add(new Student(3, "Adam"));

      Iterator<Student> iterator = linkedList.iterator();
      iterator.forEachRemaining(i -> System.out.println(i));    
   }
}

class Student {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }
   
   @Override
   public boolean equals(Object obj) {
      Student s = (Student)obj;
      return this.rollNo == s.rollNo && this.name.equalsIgnoreCase(s.name);
   }
}

Let us compile and run the above program, this will produce the following result −

[ 1, Julie ]
[ 2, Robert ]
[ 3, Adam ]