Invoking a method on a static object in Java evaluates some incorrect value

Question

The following simple program retrieves the current year (2011) from the system and then simply subtracts 1950 from the current year.

package calculation;

import java.util.Calendar;

final public class Main
{
    private static final Main INSTANCE = new Main();
    private static final int CURRENT_YEAR = Calendar.getInstance().get(Calendar.YEAR);
    private final int beltSize=CURRENT_YEAR - 1950;

    private int beltSize()
    {
        return beltSize;
    }
    public static void main(String[] args)
    {
        Main  main=new Main();
        System.out.println("Wears a size " + main.beltSize() + " belt.");
        System.out.println("Wears a size " + INSTANCE.beltSize() + " belt.");
    }
}

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The following statement from the code above returns a correct value.

Main  main=new Main();

System.out.println("Wears a size " + main.beltSize() + " belt.");

It invokes the beltSize() method which returns correctly the evaluation of CURRENT_YEAR - 1950 which is 61.

---

private static final Main INSTANCE = new Main();

System.out.println("Wears a size " + INSTANCE.beltSize() + " belt.");

The above statement invokes the same method beltSize() using the static final object INSTANCE which is a class member and it returns incorrectly -1950 (negative) rather than the correct value of 61. Why?

Answer 1

Order of evaluation matters for static variables. so change the order as

private static final int CURRENT_YEAR = Calendar.getInstance().get(Calendar.YEAR);
private static final Main INSTANCE = new Main();   // order of evaluation matters for static variables

Since INSTANCE has evaluated before CURRENT_YEAR, the default value of CURRENT_YEAR (0) has taken.