I am trying to understand generics in Java.
private List<Own> l = new ArrayList<Own>(); I have the following error :
no instance of Typed array variable T exist so that List<Own> conform to T[] when I pass it in a method (readTypedArray) that expects T[].
private List<Own> list = new ArrayList<Own>(); private OwnParceable(Parcel in) { in.readTypedArray(list, CategoriesParceable.CREATOR); } The method in.readTypedArray() expects an array T[], but you passed a List<Own which is not an array.
List is not an array you can't use it where an array is expected, List is an interface which extends Collection while array is a data structure in Java, check Difference between List and Array for further details.
You can either declare an Own[]instead of List<Own> or convert this list into an array before passing it to the method, check Convert list to array in Java:
in.readTypedArray(list.toArray(new Own[list.size()]), CategoriesParceable.CREATOR); This has nothing to do with generics - Lists and arrays are just two different things. If your method expects an array, you need to pass it an array, not a List:
Own[] arr = new Own[10]; // Or some size that makes sense... in.readTypedArray(arr, CategoriesParceable.CREATOR); There is a possibility to create an array filled with content of specified List. To achieve that you can call method toArray() of your list reference, for example:
Integer[] array = list.toArray(new Integer[list.size()]); 
Listis not[].