Question

I’d like to write singleton class for java.
I found a sample program, as follows.

public class Singleton {
  private static Singleton singleton = new Singleton();

  private Singleton() {
    System.out.println("instance is created.");
  }

  public static Singleton getInstance() {
    return singleton;
  }
}

You know, constructor is private method, not called.

How can I make a singleton instance?

When an instance is created in java program?

thank you.

Answer 1

The singleton instance will be created the first time you’ll call Singleton.getInstance(). The class will be loaded, and the singleton variable initialized, and returned by the getInstance() method.