In this section, you will learn about singleton pattern in Java.

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();
}
}

 

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