java basics static method

Question

can a static method be invoked before even a single instances of the class is constructed?

Answer 1

Yes, because static methods cannot access instance variables, so all the JVM has to do is run the code.

Answer 2

Yes, you can access it by writing ClassName.methodName before creating any instance.

Answer 3

absolutely, this is the purpose of static methods:

class ClassName {

     public static void staticMethod() {

     }
}

In order to invoke a static method you must import the class:

import ClassName;
// ...
ClassName.staticMethod();

or using static imports (Java 5 or above):

import static ClassName.staticMethod;
// ...
staticMethod();

Answer 4

Yes, that is exactly what static methods are for.

ClassName.staticMethodName();

Answer 5

Not only can you do that, but you should do it.

Answer 6

Static methods are meant to be called without instantiating the class.

Answer 7

As others have already suggested, it is definitely possible to call a static method on a class without (previously) creating an instance--this is how Singletons work. For example:

import java.util.Calendar;
public class MyClass 
{
    // the static method Calendar.getInstance() is used to create 
    // [Calendar]s--note that [Calendar]'s constructor is private
    private Calendar now = Calendar.getInstance();
}

If you mean, "is it possible to automatically call a specific static method before the first object is initialized?", see below:

public class MyClass
{
    // the static block is garanteed to be executed before the
    // first [MyClass] object is created.
    static {
        MyClass.init();
    }

    private static void init() {
        // do something ...
    }
}

Answer 8

In fact, there are a lot of "utility classes", like Math, Collections, Arrays, and System, which are classes that cannot be instantiated, but whose whole purpose is to provide static methods for people to use.