Casting to generic type in Java doesn’t raise ClassCastException?

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Java generics use type erasure, meaning those parameterized types aren’t retained at runtime so this is perfectly legal:

List<String> list = new ArrayList<String>();
list.put("abcd");
List<Integer> list2 = (List<Integer>)list;
list2.add(3);

because the compiled bytecode looks more like this:

List list = new ArrayList();
list.put("abcd");
List list2 = list;
list2.add(3); // auto-boxed to new Integer(3)

Java generics are simply syntactic sugar on casting Objects.

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