为什么java不能将类型作为参数？

public class MyList<T> {
    private T[] elements;
    private int size;

    public MyList(int initialCapacity) {
        elements = (T[]) new Object[initialCapacity];
        size = 0;
    }

    public void add(T element) {
        elements[size++] = element;
    }

    public T get(int index) {
        return elements[index];
    }
}

MyList<Integer> intList = new MyList<>(10);
MyList<String> stringList = new MyList<>(20);