Object.getClass() return type.

gistfile1.java

import java.util.ArrayList;
import java.util.List;

/**
 * <p>Demonstrating why the Object.getClass() method's return type should be
 * Class<? extends |T|> but not Class<? extends T>, where |T| is the erasure
 * of the static type T. </p>
 * <p>
 * Type parameter of every Class instance should always be reifiable type
 * or wildcard type with reifiable upper bound.
 * </p>
 * @author Ryo Asai
 */
public class FakeClassFactory<T> {
	T data;
	
	public FakeClassFactory(T data) {
		this.data = data;
	}

	@SuppressWarnings("unchecked") // really unsafe
	public Class<? extends T> getClassUnsafe() {
		return (Class<? extends T>)data.getClass();
	}
	
	public static void main(String[] args) throws Exception {
		List<String> strList = new ArrayList<String>();
		List<Integer> intList = new ArrayList<Integer>();
		
		FakeClassFactory<List<String>> fakeStrListClassFactory = new FakeClassFactory<List<String>>(strList);
		Class<? extends List<String>> fakeStrListClass = fakeStrListClassFactory.getClassUnsafe();

		FakeClassFactory<List<Integer>> fakeIntListClassFactory = new FakeClassFactory<List<Integer>>(intList);
		Class<? extends List<Integer>> fakeIntListClass = fakeIntListClassFactory.getClassUnsafe();

		// Actually the same instance.
		// Because the type parameter T is erased, and there is really no 
		// runtime representation of the parameterized type such as List<String>.
		System.out.println(fakeStrListClass == fakeIntListClass);
		
		// Invalid cast but no warnings at this line. 
		strList = fakeStrListClass.cast(intList);
		strList.add("test");
		
		int value = intList.get(0); // ClassCastException 
	}
}