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Java LinkedList removeFirst() Method

The Java LinkedList removeFirst() method retrieves and removes the first element of this linkedList. This operation modifies the arraydeque instance.

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

public E removeFirst()

NA

This method returns the head (first element) of this linkedList.

NoSuchElementException − if this linkedList is empty.

The following example shows the usage of Java LinkedList removeFirst() method with Integers. We're creating an LinkedList of Integers, adding some elements, print it and then use removeFirst() method to get the first element. As LinkedList is modified it is printed to check if first element is removed or not.

package com.tutorialspoint;

import java.util.LinkedList;

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

      // use add() method to add elements in the linkedList
      linkedList.add(25);
      linkedList.add(30);
      linkedList.add(20);
      linkedList.add(18);        

      // let us print all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);

      // it will retrieve first element after removing from linkedList
      System.out.println("Retrieved Element is = " + linkedList.removeFirst());
	  
      // let us print all the elements available in linkedList again
      System.out.println("LinkedList = " + linkedList);
   }
}

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

LinkedList = [25, 30, 20, 18]
Retrieved Element is = 25
LinkedList = [30, 20, 18]

The following example shows the usage of Java LinkedList removeFirst() method with Strings. We're creating an LinkedList of String, adding some elements, print it and then use removeFirst() method to get the first element. As LinkedList is modified it is printed to check if first element is removed or not.

package com.tutorialspoint;

import java.util.LinkedList;

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

      // use add() method to add elements in the linkedList
      linkedList.add("A");
      linkedList.add("B");
      linkedList.add("C");
      linkedList.add("D");        

      // let us print all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);

      // it will retrieve first element after removing from linkedList
      System.out.println("Retrieved Element is = " + linkedList.removeFirst());
	  
      // let us print all the elements available in linkedList again
      System.out.println("LinkedList = " + linkedList);
   }
}

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

LinkedList = [A, B, C, D]
Retrieved Element is = A
LinkedList = [B, C, D]

The following example shows the usage of Java LinkedList removeFirst() method with Student objects. We're creating an LinkedList of Student, adding some elements, print it and then use removeFirst() method to get the a first student removed. As LinkedList is modified it is printed to check if first student object is removed or not.

package com.tutorialspoint;

import java.util.LinkedList;

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"));       

      // let us print all the elements available in linkedList
      System.out.println("LinkedList = " + linkedList);

      // it will return true after removing first student from linkedList
      System.out.println("Retrieved Element is = " + linkedList.removeFirst());
	  
      // let us print all the elements available in linkedList again
      System.out.println("LinkedList = " + linkedList);
   }
}
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 −

LinkedList = [[ 1, Julie ], [ 2, Robert ], [ 3, Adam ]]
Retrieved Element is = [ 1, Julie ]
LinkedList = [[ 2, Robert ], [ 3, Adam ]]

java_util_linkedlist.htm

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