Question

I have

public class A {
    static X s_x = new X(A.class);
}

and

public class B {
    static X s_x = new X(B.class);
}

and so on for many classes without any special relationship or commonality. What I really wish I could do is have s_x initialized in a superclass, but with descendant-class-specific code; this is impossible since static code is not overridable. So, I want to at least make my copy-paste easier. I want a magic expression which evaluates to the Class object, i.e. to write:

    static X s_x = new X(/* magic expression here */);

where the magic expression is the same regardless of the class in which I declare my X in, but does the same as the examples above. Second-best option would be a static method to the same effect.

Notes:

• Java 6 if possible.
• This question is not (necessarily) about logging…

Answer 1

Some of the answers here have the idea for a solution, but not quite the code snippet I need. So here it is, working on any JVM:

static X s_x = new X(getClassStatic());

public static Class<?> getClassStatic() {
    try {
        // we're using the third highest stack element, since the
        // first highest is the getStackTrace() method, followed by this method itself. We
        // want the calling code's class.
        String name = Thread.currentThread().getStackTrace()[2].getClassName();
        return Class.forName(name);
    } catch (ClassNotFoundException e) {
        // shouldn't be able to get here...
        return null;
    }
}

or, for selected JVMs, as per Peter Lawrey’s suggestion:

static X s_x = new X(getCallerClass(1));