Java – why collection ToArray (t []) does not use E []

The toArray method (selected in java.util.arraylist) is as follows:

class ArrayList<E> ....{
    public <T> T[] toArray(T[] a){
        if(a.length < size)
            return (T[]) Arrays.copyof(elementData,size,a.getClass());
        System.arraycopy(elementData,a,size);
        if(a.length > size)
            a[size] = null;
        return a;
    }    
}

I wonder if we can use < E > instead of < T > in this case? like

public E[] toArray(E[] a){
      if(a.length < size)
             return (E[]) Arrays.copyof(elementData,a.getClass());
      System.arraycopy(elementData,size);
      if(a.length > size)
            a[size] = null;
      return a;
}

Since the ArrayList class itself is already generic to < E >, we can use it instead of the new generic type < T >?

Solution

< T > if the required array is base class E. for example, if e is HashMap, but the required array is map [] This is not possible if toArray is locked to E

Because of type erasure, something of this type is not required in a common collection / type But there is no type erasure and array, so the type of array can be very important