Field of same name in subclass as superclass

[colin shuker]

Hi, I was reading this book, and came across this code regarding the Singleton class, and extending this class:

public class Singleton {
 
    protected static Singleton uniqueInstance;
 
    protected Singleton() {}
 
    public static synchronized Singleton getInstance() {
        if (uniqueInstance == null) {
    uniqueInstance = new Singleton();
}
    return uniqueInstance;
}
 
 
 
public class CoolerSingleton extends Singleton {
 
    protected static Singleton uniqueInstance;
 
    private CoolerSingleton() {
        super();
    }
    
    // useful methods here
}

As you can see, the uniqueInstance variable is present in both classes.
Obviously we need it in the superclass, but why is it present in the subclass?
I did a little test, and it seems they are equal.
Is this just for clarity? What generally happens with variables of the same name in a superclass and subclass?

Thanks for any info.

I've just re-read the post, and noticed the uniqueInstance gets sets to the type of the superclass, so surely this won't work since we want a CoolerSingleton object stored there?
[ May 14, 2007: Message edited by: colin shuker ]