Question

I want to understand what does the word ‘static’ do in the ‘writeNumbers’ method header?:

public class DisplayClass {

    /**
     * @param args
     */
    public static void main(String[] args) {
        writeNumbers();
    }

    public static void writeNumbers()
    {
        int count;
        for(count=1; count<=20; count++)
        {
            System.out.println(count);
        }
    }
}

Answer 1

The term static means that the method is available at the Class level, and so does not require that an object is instantiated before it’s called.

Because writeNumbers was being called from a method that was itself static it can only call other static methods, unless it first instantiates a new object of DisplayClass using something like:

DisplayClass displayClass = new DisplayClass();

only once this object has been instantiated could non-static methods been called, eg:

displayClass.nonStaticMethod();