Array Conversion To List Error [duplicate]

Question

could someone explain to me what happens in the next lines of code and why it works?

Integer[] myray = {1,2,3,4,5};
List<Integer> l = new ArrayList<Integer>(Arrays.asList(myray));
l.add(6);
System.out.println(l);

The code above works fine. It converts an array to a list and then adds another element. But the following code dose not work

Integer[] myray = {1,2,3,4,5};
List<Integer> l = (Arrays.asList(myray));
l.add(6);
System.out.println(l);

The above code gives me the following error: Exception in thread "main" java.lang.UnsupportedOperationException Can someone please tell me the difference between the two conversions and why only the first one works?? Thanks in advance

Answer 1

Arrays.asList(myray) returns a fixed sized List implementation (java.util.Arrays.ArrayList) backed by an array, so you can't add elements to it (or remove elements from it).

When you create a new java.util.ArrayList and pass to its constructor the fixed sized List you got from Arrays.asList (as you do in your first snippet), you get a normal java.util.ArrayList to which you can add elements.