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Exception while using arrays.aslist() method

Maheswaran Devaraj
Ranch Hand

Joined: Sep 14, 2007
Posts: 47
Hi All,

I got a list from the Arrays.asList() method() while i try to remove a element from it the compiler spiting the unsupported exception.Can any one explain the code.




Thanks and Regards,
Mahes
Rob Spoor
Sheriff

Joined: Oct 27, 2005
Posts: 19674
    
  18

Arrays.asList returns an unmodifiable List view of the array. You can't add to or remove from this list.

Change your list code to this:


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Ernest Friedman-Hill
author and iconoclast
Marshal

Joined: Jul 08, 2003
Posts: 24183
    
  34

To create a modifiable list from an array, you can do something like

List modifiable = new ArrayList(Arrays.asList(theArray));


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Mike Simmons
Ranch Hand

Joined: Mar 05, 2008
Posts: 3012
    
  10
Rob Prime wrote:Arrays.asList returns an unmodifiable List view of the array. You can't add to or remove from this list.

I think calling it unmodifiable is misleading, since you can set() an element. You just can't do anything that would change the length, like add() or remove(). Just like an array.
Rob Spoor
Sheriff

Joined: Oct 27, 2005
Posts: 19674
    
  18

You're right, I forgot about setting new values.

So let's phrase it like this: with the List returned by Arrays.asList, you can't perform an operation that is not supported by the backing array. Arrays allow setting, but not changing the size in any way, and neither does this List.
 
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