Java LinkedList pop() Method

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Description

The Java util LinkedList pop() method pops an element from the stack represented by this linkedList. Essentially it removes the first element of the LinkedList object.

Declaration

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

 public E pop() 

Parameters

NA

Return Value

This method returns the element at the front of this linkedList.

Exception

NoSuchElementException − if this linkedList is empty.

Getting the First Element of the LinkedList of Integers Example

The following example shows the usage of Java LinkedList pop() method with Integers. We're creating an LinkedList of Integers, adding some elements, print it and then use pop() 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.pop()); // let us print all the elements available in linkedList again System.out.println("LinkedList = " + linkedList); } } 

Output

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] 

Getting the First Element of the LinkedList of Strings Example

The following example shows the usage of Java LinkedList pop() method with Strings. We're creating an LinkedList of String, adding some elements, print it and then use pop() 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.pop()); // let us print all the elements available in linkedList again System.out.println("LinkedList = " + linkedList); } } 

Output

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] 

Getting the Last Element of the LinkedList of Objects Example

The following example shows the usage of Java LinkedList pop() method with Student objects. We're creating an LinkedList of Student, adding some elements, print it and then use pop() 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<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 retrieve first element after removing from linkedList System.out.println("Retrieved Element is = " + linkedList.pop()); // 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); } } 

Output

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 ]]