如何在其他类中使用公共常量？

Question

I'm trying to access a public constant variable outside my class and I don't understand why isn't working. I declared the variable y in this class:

package test;

public class TestConstant 
{
    public static final double y = 1;
    public static void main(String[] args) 
    {       
        
        System.out.println(y);
    }
}

It worked fine, I had the output 1 as expected.

Now I'm trying to access this variable outside my class:

package test;

public class TestConstant2 
{
    public static void main(String[] args)
    {       
        System.out.println(y);
    }

}

I couldn't run the last source code. How can I use public constants outside a class it was declared in?

Answer 1

Constants live in the class where you defined them.

package test;

public class TestConstant2 
{
    public static void main(String[] args)
    {       
        System.out.println(TestConstant.y);
    }

}

Answer 2

You have to add the class name in front of the constant:

package test;

public class TestConstant2 
{
    public static void main(String[] args)
    {       
        System.out.println(TestConstant.y);
    }
}

or import it with static

package test;

import static TestConstant.y;

public class TestConstant2 
{
    public static void main(String[] args)
    {       
        System.out.println(y);
    }
}

BTW: static final variables should be upper case