calling non-static method in static method in Java

Question

This question already has an answer here:

• Cannot make a static reference to the non-static method 8 answers

I'm getting an error when I try to call a non-static method in a static class.

Cannot make a static reference to the non-static method methodName() from the type playback

I can't make the method static as this gives me an error too.

This static method cannot hide the instance method from xInterface

Is there any way to get round calling an non-static method in another static method? (The two methods are in seperate packages and seperate classes).

Answer 1

The only way to call a non-static method from a static method is to have an instance of the class containing the non-static method. By definition, a non-static method is one that is called ON an instance of some class, whereas a static method belongs to the class itself.

Answer 2

Constructor is a special method which in theory is the "only" non-static method called by any static method. else its not allowed.

Answer 3

There are two ways:

1. Call the non-static method from an instance within the static method. See fabien's answer for an oneliner sample... although I would strongly recommend against it. With his example he creates an instance of the class and only uses it for one method, only to have it dispose of it later. I don't recommend it because it treats an instance like a static function.
2. Change the static method to a non-static.

Answer 4

You need an instance of the class containing the non static method.

Is like when you try to invoke the non-static method startsWith of class String without an instance:

 String.startsWith("Hello");

What you need is to have an instance and then invoke the non-static method:

 String greeting = new String("Hello World");
 greeting.startsWith("Hello"); // returns true 

So you need to create and instance to invoke it.

Answer 5

You can't get around this restriction directly, no. But there may be some reasonable things you can do in your particular case.

For example, you could just "new up" an instance of your class in the static method, then call the non-static method.

But you might get even better suggestions if you post your class(es) -- or a slimmed-down version of them.

Answer 6

The only way to call a non-static method from a static method is to have an instance of the class containing the non-static method.

class A
{
    void method()
    {
    }
}
class Demo
{
    static void method2()
    {
        A a=new A();

        a.method();
    }
    /*
    void method3()
    {
        A a=new A();
        a.method();
    }
    */

    public static void main(String args[])
    {
        A a=new A();
        /*an instance of the class is created to access non-static method from a static method */
        a.method();

        method2();

        /*method3();it will show error non-static method can not be  accessed from a static method*/
    }
}