Immodifable List

[SanjayR Jain]

I have this piece of code.

      String[] s=new String[2];
		List<String> kk= Arrays.asList(s);
		kk.add("tt");  

Its is giving this exception:java.lang.UnsupportedOperationException
But I am not getting that, why it is not possible to add element in list.

[Wouter Oet]

Because Arrays.asList returns a fixed-size list. So you can't add or remove items.

[Jesper de Jong]

The list that Arrays.asList(...) returns is a view on the underlying array. It doesn't create a regular list initialized with a copy of the content of the array; instead, it just provides an object that implements List, so that you can use the array as if it is a List (note that the API documentation of Arrays.asList(...) explains this). Arrays in Java cannot be resized, so you can't add elements to the List that Arrays.asList(...) returns.

If you want a normal, resizable List that contains a copy of the elements of the array, try something like this:

List<String> kk = new ArrayList<String>(Arrays.asList(s));