Java Generic Class – Determine Type


If I am creating a java class to be generic, such as:

public class Foo<T>

How can one determine internally to that class, what 'T' ended up being?

public ???? Bar()
    //if its type 1
    //    do this
    //if its type 2
    //    do this
    //if its type 3
    //    do this
    //if its type 4
    //    do this

I've poked around the Java API and played with the Reflection stuff, instanceof, getClass, .class, etc, but I can't seem to make heads or tails of them. I feel like I'm close and just need to combine a number of calls, but keep coming up short.

To be more specific, I am attempting to determine whether the class was instantiated with one of 3 possible types.

Best Solution

I've used a similar solution to what he explains here for a few projects and found it pretty useful.

The jist of it is using the following:

 public Class returnedClass() {
     ParameterizedType parameterizedType = (ParameterizedType)getClass()
     return (Class) parameterizedType.getActualTypeArguments()[0];