Is it better to have a single instance of a class, or simply have a bunch of static methods? [closed]

Question

I've been using several methods of calling methods. More recently, I've been using a static instance of a class, I do believe that's the proper term for it (please correct me if I'm wrong). Which is better (or even suggest ideas), and why?

The first way I was the simple old static methods.

static void exampleMethod1(){}
static void exampleMethod2(){}

The second way (someone said this is an improvement).

public class ExampleClass{

    public static ExampleClass instance;

    public ExampleClass(){
    instance = this;
    }

    public static ExampleClass getInstance(){
        return instance;
    }

    void exampleMethod1(){
        //code
    }

    void exampleMethod2(){
        //code
    } 

    // To call the method I simply getInstance().exampleMethod1    

}

Answer 1

The term you're looking for is singleton.

Both static methods and instance methods on a singleton are okay approaches, but note that the static methods approach cannot implement an interface, so if you need to implement an interface, use a singleton.

For example:

public enum HelloWorld implements Runnable {
    INSTANCE;

    @Override
    public void run() {
        System.out.println("Hello, world!");
    }
}

// ...
new Thread(HelloWorld.INSTANCE).start();

If your hello-world code were in a static method, it wouldn't have been able to directly implement the Runnable interface.