Java Singleton Example

//Sun as a Singleton - example
class Sun {

    //STEP 2 - make class create instance of itself
    private static Sun instance = new Sun();

    private Sun() { //STEP 1 - make all constructors private
    }

    public String toString() {
        return "the sun";
    }

    //STEP 3 - provide a static getInstance method
    public static Sun getInstance() {
        return instance;
    }
}


public class SunTester {
    public static void main(String args[]) {
        //create object using static getInstance() method
        Sun sun1 = Sun.getInstance();
        Sun sun2 = Sun.getInstance();

        //call instance methods using object ref
        System.out.println(sun1.toString());


        //if both sun1 and sun2 object refs point to same object
        //this comparison will be true
        System.out.println(sun1 == sun2);
        //and object hashcode will be same also
        System.out.println(sun1.hashCode() + " = " +sun2.hashCode());

    }
}