public class Box<T> {
private T element;
public T getElement() {
return element;
}
public void setElement(T element) {
this.element = element;
}
}
public class Test {
public static void main(String[] args) {
List<Box> l = new ArrayList<>(); //Just List of Box with no specific type
Box<String> box1 = new Box<>();
box1.setElement("aa");
Box<Integer> box2 = new Box<>();
box2.setElement(10);
l.add(box1);
l.add(box2);
//Case 1
Box<Integer> b1 = l.get(0);
System.out.println(b1.getElement()); //why no error
//Case 2
Box<String> b2 = l.get(1);
System.out.println(b2.getElement()); //throws ClassCastException
}
}
The list l holds element of type Box. In case 1, I get the first element as Box<Integer> and in second case the second element in the list is obtained as Box<String>. The ClassCastException is not thrown in the first case.
When I tried to debug, the element's type in b1 and b2 are String and Integer respectively.
Is it related to type erasure?