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javasingletonsingleton-methods
Arundas K V
Arundas K V

Reputation: 809

Best way to call a method inside a singleton class

I have a singleton class

public class Singleton {
static Singleton instance;
public static Singleton getInstance() 
{
    if (instance == null) 
    {
        instance = new Singleton();
    }
    return instance;
}

Consider a public function method() is defined inside the class Singleton.

Which is the best way to call a method inside a singleton class:

Singleton.method() - method calling statically

or

Singleton.getInstance.method() - method not static ?

Upvotes: 2

Views: 22854

Answers (7)

abishek kachroo
abishek kachroo

Reputation: 45

Here you are having getInstance() as a static method and you have created method as a non-static or instance method.

So for a static method, Class.method_name format can be used, but for an instance method object needs to be created.

It may not be the correct syntax as shown over there:

Singleton.getInstance().method();

Singleton obj = new Singleton();
obj.method();

should be the correct format

Upvotes: 0

Sami Eltamawy
Sami Eltamawy

Reputation: 10009

First, you should make sure that you have declared your Constructor as a private one to prevent any one to call it and re-initialize it again. As following:

private void Singleton(){
    //Initialize your private data
}

Second, call the static methods directly as following:

Singleton.yourMethod();

Third:, the non-static method calling as following:

Singleton.getInstance().yourMethod();

Here is a good Example of the Singleton classes

Upvotes: 2

zapl
zapl

Reputation: 63955

The singleton pattern allows you to control the amount of instances that exist of one class - i.e. just 1. But the class itself is still a normal class that is not supposed to know how many of it's kind exist and it should therefore have normal instance methods.

When using static methods, you'll run into terrible problems if you ever want to change how many instances of that class exist.

Either use a singleton or use static methods.

Upvotes: 2

Niko
Niko

Reputation: 8153

If you want to use Singleton pattern:

public class Singleton {
    private static Singleton sInstance;

    public static Singleton getInstance() {
        if (sInstance == null) {
            sInstance = new Singleton();
        }

        return sInstance;
    }

    // Prevent duplicate objects
    private Singleton() {

    }

    public void method() {

    }
}

Upvotes: 2

vipul mittal
vipul mittal

Reputation: 17401

In case of singleton classes there is no use of static methods as there is only one instance available of the class and every buddy is having the same copy of it.

so always create an instance method and call:

Singleton.getInstance().method();

Upvotes: 12

Adhikari Bishwash
Adhikari Bishwash

Reputation: 2780

Singleton.getInstance().method();

is better as when called for first time instance will be null and instance is only created in getInstance().

Upvotes: 0

Blackbelt
Blackbelt

Reputation: 157457

In the first case:

Singleton.method();

method have to be static

In the second case:

Singleton.getInstance().method();

the method is not static.

So those are conceptually different

Upvotes: 1

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