- Trending Categories
Data Structure
Networking
RDBMS
Operating System
Java
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
How to make a singleton enum in Java?
The singleton pattern restricts the instantiation of a class to one object. INSTANCE is a public static final field that represents the enum instance. We can get the instance of the class with the EnumSingleton.INSTANCE but it is better to encapsulate it in a getter in case if we want to change the implementation.
There are a few reasons why we can use an enum as a singleton in Java
- Guaranteed one instance (Cannot instantiate more than one enum even through reflection).
- Thread-safe.
- Serialization.
Syntax
public enum Singleton { INSTANCE; private singleton() { } }
Example
public enum EnumSingleton { INSTANCE; private String name; private int age; private void build(SingletonBuilder builder) { this.name = builder.name; this.age = builder.age; } public static EnumSingleton getSingleton() { // static getter return INSTANCE; } public void print() { System.out.println("Name: "+name + ", age: "+age); } public static class SingletonBuilder { private final String name; private int age; private SingletonBuilder() { name = null; } public SingletonBuilder(String name) { this.name = name; } public SingletonBuilder age(int age) { this.age = age; return this; } public void build() { EnumSingleton.INSTANCE.build(this); } } public static void main(String[] args) { new SingletonBuilder("Adithya").age(25).build(); EnumSingleton.getSingleton().print(); } }
Output
Name: Adithya, age: 25
- Related Articles
- How to make a class singleton in Java?\n
- How to prevent Cloning to break a Singleton Class Pattern in Java?
- How to convert a String to an enum in Java?
- What is a singleton class in Java?
- How to call another enum value in an enum's constructor using java?
- Enum in Java
- Enum in a class in Java
- How to write a singleton class in C++?
- How to iterate the values in an enum in Java?
- How to convert a JSON object to an enum using Jackson in Java?
- Enum Methods in Java
- Enum constructor in Java
- How to implement a Singleton design pattern in C#?
- How to clear Singleton instance in android?
- How to use singleton class in android?

Advertisements