Static method in a generic class?

You can't use a class's generic type parameters in static methods or static fields. The class's type parameters are only in scope for instance methods and instance fields. For static fields and static methods, they are shared among all instances of the class, even instances of different type parameters, so obviously they cannot depend on a particular type parameter.

It doesn't seem like your problem should require using the class's type parameter. If you describe what you are trying to do in more detail, maybe we can help you find a better way to do it.

Java doesn't know what T is until you instantiate a type.

Maybe you can execute static methods by calling Clazz<T>.doit(something) but it sounds like you can't.

The other way to handle things is to put the type parameter in the method itself:

static <U> void doIt(U object)

which doesn't get you the right restriction on U, but it's better than nothing....

I ran into this same problem. I found my answer by downloading the source code for Collections.sort in the java framework. The answer I used was to put the <T> generic in the method, not in the class definition.

So this worked:

public class QuickSortArray  {
    public static <T extends Comparable> void quickSort(T[] array, int bottom, int top){
//do it
}

}

Of course, after reading the answers above I realized that this would be an acceptable alternative without using a generic class:

public static void quickSort(Comparable[] array, int bottom, int top){
//do it
}