CODEWITHSUNDEEP
javaarraysstringarraylistclasscastexception
Christian
Christian

Reputation: 1411

ArrayList.toString Exception

I am using a ArrayList to store some Strings form an array of strings:

ArrayList<String> list = new ArrayList<>();
list.add(strings[i]);

To give those to another function I converted them back into an Array:

foo((String[]) list.toArray());

this gives me an exeption:

Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [Ljava.lang.String;

What am I doing wrong here?

Upvotes: 2

Views: 218

Answers (2)

Jin
Jin

Reputation: 6145

You have to do

String[] t = new String[list.size()];
foo(list.toArray(t));

Upvotes: 1

Andy Thomas
Andy Thomas

Reputation: 86409

The method call list.toArray() returns an array of type Object[]. You can't cast that to String[], even though it contains only Strings.

But you can create an array of type String[] with a sibling of List.toArray() that accepts an initial array of the desired type:

 foo( list.toArray( new String[ list.size() ] ) );

Upvotes: 5

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