Java Deque remove() Method with Examples

Description

The java Deque remove() method retrieves and removes the head of the queue represented by this deque.

Declaration

Following is the declaration for java.util.Deque.remove() method

public E remove()

Parameters

NA

Return Value

This method returns the head of the queue represented by this deque.

Exception

NoSuchElementException − if this deque is empty.

remove() method with Object as parameter

Description

The Java Deque remove(Object) method removes a single instance of the specified element from this deque.

Declaration

Following is the declaration for java.util.Deque.remove(o) method

public boolean remove(Object o)

Parameters

o − The element to be removed from this deque, if present

Return Value

This method returns true if this deque contains the specified element.

Exception

ClassCastException − if the class of the specified element is incompatible with this deque (optional)

NullPointerException − iif the specified element is null and this deque does not permit null elements (optional)

Example #1

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

package com.tutorialspoint;

import java.util.ArrayDeque;
import java.util.Deque;

public class DequeDemo {
   public static void main(String[] args) {
      
      // create an empty array deque
      Deque<Integer> deque = new ArrayDeque<>();

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

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

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

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

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

Example #2

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

package com.tutorialspoint;

import java.util.ArrayDeque;
import java.util.Deque;

public class DequeDemo {
   public static void main(String[] args) {
      
      // create an empty array deque
      Deque<String> deque = new ArrayDeque<>();

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

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

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

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

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

Example #3

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

package com.tutorialspoint;

import java.util.ArrayDeque;
import java.util.Deque;

public class DequeDemo {
   public static void main(String[] args) {
      
      // create an empty array deque
      Deque<Student> deque = new ArrayDeque<>();

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

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

      // it will return true after removing Robert from deque
      System.out.println("Student removed :" + deque.remove(new Student(2, "Robert")));
	  
      // let us print all the elements available in deque again
      System.out.println("Deque = " + deque);
   }
}
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 −

Deque = [[ 1, Julie ], [ 2, Robert ], [ 3, Adam ]]
Student removed : true
Deque = [[ 1, Julie ], [ 3, Adam ]]