Question

This has bothered me for a long time, so I thought I’d go ahead and ask.

If I write

import java.util.*;
import java.lang.*;

class Main
{
    public static void main (String[] args) throws java.lang.Exception
    {
            new Shape();
            new Triangle();
    }

    public static class Shape
    {
            static String name = "shape";

            Shape()
            {
                    printName();
            }

            public void printName()
            {
                    System.out.println( name() );
            }

            public String name()
            {
                    return name;
            }
    }

    public static class Triangle extends Shape
    {
            static String name = "triangle";

            public String name()
            {
                    return name;
            }
    }
}

then the output is

shape
triangle

But if I write

import java.util.*;
import java.lang.*;

class Main
{
    public static void main (String[] args) throws java.lang.Exception
    {
            new Shape();
            new Triangle();
    }

    public static class Shape
    {
            static String name = "shape";

            Shape()
            {
                    printName();
            }

            public void printName()
            {
                    System.out.println( name );
            }

    }

    public static class Triangle extends Shape
    {
            static String name = "triangle";
    }
}

then the output is

shape
shape

In the first version, I have to copy/paste the same function getName() over and over into every subclass. There’s has to be a better way. What do I need to change in the second example?

Answer 1

static fields aren’t accessible from parent classes. The class Shape doesn’t “see” the static field name of the class Triangle and uses his own static field name.

UPD: You ask: what do you need to change in the second example? More specifically, your first example is a correct “fixing” of your second example. The only correct way is using some getter method like your name() method.

UPD2: (from my commentary): Well, another way: forgive about any kind of field name. Use instead a method called name() (not static!) which will return in each class the needed name. Just return "shape"; or return "triangle" in them;