Java ArrayDeque removeLastOccurrence() Method

🎓 Top 15 Udemy Courses (80-90% Discount): My Udemy Courses - Ramesh Fadatare — All my Udemy courses are real-time and project oriented courses.

▶️ Subscribe to My YouTube Channel (178K+ subscribers): Java Guides on YouTube

▶️ For AI, ChatGPT, Web, Tech, and Generative AI, subscribe to another channel: Ramesh Fadatare on YouTube

The ArrayDeque class in Java provides the removeLastOccurrence() method to remove the last occurrence of a specified element from the deque.

Table of Contents

1. Introduction
2. removeLastOccurrence Method Syntax
3. Examples
   • Removing the Last Occurrence of an Element in the ArrayDeque
   • Handling an Element Not Present in the ArrayDeque
4. Real-World Use Case
   • Use Case: Task Management System
5. Conclusion

Introduction

The ArrayDeque.removeLastOccurrence(Object o) method is used to remove the last occurrence of the specified element from the deque. If the element is not present, the deque remains unchanged.

removeLastOccurrence Method Syntax

The syntax for the removeLastOccurrence method is as follows:

public boolean removeLastOccurrence(Object o) 

• The method takes a single parameter o of type Object, which is the element to be removed from the deque.
• The method returns a boolean value: true if the deque was modified as a result of the call, false otherwise.

Examples

Removing the Last Occurrence of an Element in the ArrayDeque

The removeLastOccurrence method can be used to remove the last occurrence of a specified element in an ArrayDeque.

Example

import java.util.ArrayDeque; public class ArrayDequeRemoveLastOccurrenceExample { public static void main(String[] args) { // Creating an ArrayDeque of Strings ArrayDeque<String> tasks = new ArrayDeque<>(); // Adding elements to the ArrayDeque tasks.add("Complete project report"); tasks.add("Email client updates"); tasks.add("Prepare presentation"); tasks.add("Email client updates"); // Duplicate element // Removing the last occurrence of "Email client updates" boolean isRemoved = tasks.removeLastOccurrence("Email client updates"); // Printing the result of the removeLastOccurrence operation System.out.println("Was the element removed? " + isRemoved); // Printing the ArrayDeque after removal System.out.println("ArrayDeque after removeLastOccurrence: " + tasks); } } 

Output:

Was the element removed? true ArrayDeque after removeLastOccurrence: [Complete project report, Email client updates, Prepare presentation] 

Handling an Element Not Present in the ArrayDeque

When the specified element is not present in the ArrayDeque, the removeLastOccurrence method returns false.

Example

import java.util.ArrayDeque; public class ElementNotPresentRemoveLastOccurrenceExample { public static void main(String[] args) { // Creating an ArrayDeque of Strings ArrayDeque<String> tasks = new ArrayDeque<>(); // Adding elements to the ArrayDeque tasks.add("Complete project report"); tasks.add("Email client updates"); // Attempting to remove an element not present in the ArrayDeque boolean isRemoved = tasks.removeLastOccurrence("Prepare presentation"); // Printing the result of the removeLastOccurrence operation System.out.println("Was the element removed? " + isRemoved); // Printing the ArrayDeque after attempting to remove the element System.out.println("ArrayDeque after removeLastOccurrence: " + tasks); } } 

Output:

Was the element removed? false ArrayDeque after removeLastOccurrence: [Complete project report, Email client updates] 

Real-World Use Case

Use Case: Task Management System

In a task management system, you might need to remove the last occurrence of a specific task from the deque, such as a task that has been completed or canceled. The removeLastOccurrence method can help achieve this functionality.

Example

import java.util.ArrayDeque; public class TaskManagementSystem { public static void main(String[] args) { // Creating an ArrayDeque to store tasks ArrayDeque<Task> tasks = new ArrayDeque<>(); // Adding initial tasks to the ArrayDeque tasks.add(new Task("Complete project report", 2)); tasks.add(new Task("Email client updates", 1)); tasks.add(new Task("Prepare presentation", 3)); tasks.add(new Task("Email client updates", 1)); // Duplicate task // Removing the last occurrence of the specified task boolean isRemoved = tasks.removeLastOccurrence(new Task("Email client updates", 1)); // Printing the result of the removeLastOccurrence operation System.out.println("Was the task removed? " + isRemoved); // Printing the ArrayDeque after removal System.out.println("Remaining tasks in ArrayDeque: " + tasks); } } class Task { private String description; private int priority; public Task(String description, int priority) { this.description = description; this.priority = priority; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; Task task = (Task) o; if (priority != task.priority) return false; return description != null ? description.equals(task.description) : task.description == null; } @Override public int hashCode() { int result = description != null ? description.hashCode() : 0; result = 31 * result + priority; return result; } @Override public String toString() { return description + " (Priority: " + priority + ")"; } } 

Output:

Was the task removed? true Remaining tasks in ArrayDeque: [Complete project report (Priority: 2), Email client updates (Priority: 1), Prepare presentation (Priority: 3)] 

Conclusion

The ArrayDeque.removeLastOccurrence(Object o) method in Java is used for removing the last occurrence of a specified element from a deque. Understanding how to use this method allows you to efficiently manage elements in the deque, making it particularly useful in applications like task management systems where you need to remove specific tasks based on certain criteria.