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javaarraylistcasting

java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayList

Can you explain me why does this happen and how can I fix it please?

So I'm using Oracle-ADF and I'm using shuttle components. I get the selected values using the sos1.getValue();

The getValue() method returns an object and I'm trying to convert it to an ArrayList so I can work with it later. Therefore I've created the ArrayList sos1Value

However, this line of code is going bananas:

sos1Value = (ArrayList) Arrays.asList(sos1.getValue());

And I keep getting java.lang.ClassCastException: java.util.Arrays$ArrayList cannot be cast to java.util.ArrayList

I've tried other ways like: sos1Value = (ArrayList) sos1.getValue();

But I keep having the same problem, what can I do?

Solution

  • Arrays.asList returns a List implementation, but it's not a java.util.ArrayList. It happens to have a classname of ArrayList, but that's a nested class within Arrays - a completely different type from java.util.ArrayList.

    If you need a java.util.ArrayList, you can just create a copy:

    ArrayList<Foo> list = new ArrayList<>(Arrays.asList(sos1.getValue());

    If you don't need an ArrayList just remove the cast:

    List<Foo> list = Arrays.asList(sos1.getValue());

    (if you don't need any members exposed just by ArrayList).