Get class name for the generic class argument

Question

I want to find the class name of the argument sent to the generic class as follows.

public abstract class RootClass<T extends Iface> {
    protected ApplicationContext applicationContext;
    public T getIfaceBean() {
        return applicationContext.getBean(T.class);
    }
}

But it looks like I can't do T.class (due to Type Erasure?).

So, Is such an action possible with Java Generics ?

How can I achieve this type of functionality with Java Generics?

It's hacky, you're better off passing the Class type as an argument to the constructor or method. — Sotirios Delimanolis, Jul 30 '13 at 17:10
Same thing as with http://stackoverflow.com/questions/75175/create-instance-of-generic-type-in-java You have to pass the class as an argument. — Cyrille Ka, Jul 30 '13 at 17:11
You can obtain this via reflection if you have a subclass (as you must have) and concrete type. Here is an example http://ideone.com/9ZFujO — Peter Lawrey, Jul 30 '13 at 17:22
@PeterLawrey Using reflection for this purpose seems complex. I have had figure out a simple solution by requiring concrete-classes to implement `getIfaceClass()` which just do `return SubIface.class`. — TheKojuEffect, Jul 30 '13 at 17:27
That is fine if you don't have to do it very often. Doing what you believe is simplest is the best approach. — Peter Lawrey, Jul 30 '13 at 17:34
@PeterLawrey Can you please help me write code in abstract class using reflection instead of implementing `getIfaceClass()` in concrete class? — TheKojuEffect, Jul 30 '13 at 18:10

score 7 · Accepted Answer · answered Jul 30 '13 at 17:11

7

Because of Type Erasure, you can't say T.class because T doesn't exist at runtime.

The best you can do is to take a parameter of type Class<T> to get the Class object:

public T getIfaceBean(Class<T> clazz) {

answered Jul 30 '13 at 17:11

rgettman

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Get class name for the generic class argument

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