Type erasure in java

TypeErasureIsReallyWeird.java

class TypeErasureIsReallyWeird {

	private static class AndNowWithGenerics<LongActually> {
		LongActually UhOh(Object o) {
			try {
				@SuppressWarnings("unchecked")
				LongActually longish = (LongActually) o;
				System.out.println(
					"In a generic class, casting String to Long seems ok. Long value is: " +
					longish);
				return longish;
			} catch(Exception e) {
				System.out.println(
					"In a generic class, casting String to Long gave me an " +
					e.getClass().getName());
				return null;
			}
		}
	}

	public static void main(String args[]) {
		try {
			Long wontwork = (Long) (Object) "foo";
			System.out.println(
				"Casting String to Long seems ok. Long value is: " +
				wontwork);
		} catch(Exception e) {
			System.out.println(
				"Casting String to Long gave me an "
				 + e.getClass().getName());
		}
		try {
			Long weirdValueForLong = (new AndNowWithGenerics<Long>()).UhOh("bar");
			System.out.println(
				"And this is how you put a String in a Long: " + weirdValueForLong);
		} catch (Exception e) {
			System.out.println(
				"This won't work, because the Long returned here is actually a String: " +
				e.getClass().getName());
		}
	}
	
}