Java Singleton Pattern
In this section, you will learn about singleton pattern in Java.
What is Singleton Pattern ?
In Java, singleton pattern is implemented to limit the instantiation of a class to one object. Similar to static field, instance of a class will occur only once per application.
How to implement ?
You can implement the singleton pattern as given below :
SingletonDemo.java
public class SingletonDemo {
// Private constructor restrict from instantiating
private static SingletonDemo instance = new SingletonDemo();
private SingletonDemo() {
}
public static SingletonDemo getInstance() {
return instance;
}
// This methods is protected due to singleton
protected static void sampleMethod() {
System.out.println("Singleton Sample Method");
}
}
For implementing "singleton pattern", you need a private constructor( SingletonDemo() ) and a field to conatin its result(instance), and a static access method having name like getInstance().
SingletonExample.java
public class SingletonExample {
public static void main(String args[]){
SingletonDemo.sampleMethod();
}
}