Java static method vs function

Question

What is difference between this codes in java 8 :

This :

public class Hello {
    public static void sayHello() {
        System.out.println("ghasedak.Hello !!!");
    }
}

and this :

public interface Hello {
    public static void sayHello() {
        System.out.println("ghasedak.Hello !!!");
    }
}

This is main class :

public class MainClass {
    public static void main(String[] args) {
            Hello.sayHello(); //for function
            Hello.sayHello(); //for class
    } 
}

Are you sure, that java allows the method implementation in interface? — kk., Jun 08 '17 at 14:08
The difference is that one method is in a class and the other is in an interface. The class/interface is basically just a kind of namespace and the method has access to anything within that namespace (i.e. other static methods or fields). — Thomas, Jun 08 '17 at 14:09
@KrishnaKuntala interfaces can contain static methods just as they can contain static fields. — Thomas, Jun 08 '17 at 14:10
@JNomad wrong. It's a static method in an interface, not a default method. — André Stannek, Jun 08 '17 at 14:14
You should read official Java documentation about "Default Methods" : [here](https://docs.oracle.com/javase/tutorial/java/IandI/defaultmethods.html) — Mickael, Jun 08 '17 at 14:16
IMO interface static method we can't override them in implementation class — soorapadman, Jun 08 '17 at 14:21
@German In this documentation, you have a specific explaination about "Static Methods". — Mickael, Jun 08 '17 at 14:39

score 0 · Answer 1 · answered Jun 08 '17 at 14:10

In Java 8 you are now allowed to define methods in interfaces. So technically they are the same. The difference with interfaces still remains you cannot instantiate them. So you can only use the methods in them.

Here is link: https://en.wikipedia.org/wiki/Interface_(Java)

It speaks about how interfaces interact now in Java 8.

In your code, it still should call the Hello class method over the interface class method because as I said interfaces can't be instantiated.

VHS · Answer 2 · 2017-06-08T14:26:17.770

There is no difference between the two.

The first example shows a static method implemented in a class while the second one shows a static method implemented in an interface. The second example wouldn't compile if you use JDK 7 or below because as others have already said, static method support in interfaces was only added in Java 8. Here is a very useful StackOverflow article that explains why the support for static and default methods in interfaces was added in Java 8.

The choice of whether you want to keep your static method, which may be a utility method, in a class or an interface, depends on the circumstances. E.g. if you want to add a new common method to a set of classes that do not extend a common base class but do implement a common interface. You might add the common method to the interface since there is no common base class.

score 0 · Answer 3 · answered Jun 08 '17 at 14:34

I think we have two difference :
1) interfaces can only have one function .
2) important : interface is not class , so have not block static :
view this code :

public class Hello {
    static {
        System.out.println("Ok");
    }
    public static void sayHello() {
        System.out.println("ghasedak.Hello !!!");
    }
}

this block run when you call class .
you can not do this on function interfaces . (intefaces have not this block)
sorry for bad english language

Java static method vs function

3 Answers3