Casting from Object[] to String[] gives a ClassCastException

Question

The getStrings() method is giving me a ClassCastException. Can anyone tell me how I should get the model? Thanks!

public class HW3model extends DefaultListModel<String>
{           
    public HW3model()
    {
        super();
    }

    public void addString(String string)
    {
        addElement(string);
    }

    /**
     * Get the array of strings in the model.
     * @return
     */
    public String[] getStrings()
    {
         return (String[])this.toArray();
    }
}

It's a method of DefaultListModel that I'm calling. I should not have used "this" — letter Q
– letter Q, Commented Feb 18, 2013 at 23:49
He's using the method of the super class. But it doesn't return an array of String but rather an array of Object. So that's your problem. Treat it for what it is, an array of object. — Hovercraft Full Of Eels
– Hovercraft Full Of Eels, Commented Feb 18, 2013 at 23:49

MadProgrammer · Accepted Answer · 2014-01-04 19:59:51Z

2

The value returned by toArray is an Object array.

That is, they've be declared as Object[], not String[], then returned back via a Object[].

This means you could never case it to String array, it's simply invalid.

You're going to have to copy the values yourself...for example

public String[] getStrings()
    Object[] oValues= toArray();
    String[] sValues = new String[oValues.length];
    for (int index = 0; index < oValues.length; index++) {
        sValues[index] = oValues[index].toString();
    }
    return sValues;
}

edited Jan 4, 2014 at 19:59

answered Feb 18, 2013 at 23:55

MadProgrammer

348k22 gold badges243 silver badges379 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

MadProgrammer Over a year ago

You have to admire the courage of down voters who are unable to provide a comment as to why they felt it necessary to apply a downvote. It does nothing to help the poster or future posters to improve this or future questions.

beny23 · Accepted Answer · 2013-02-18 23:51:45Z

1

You can't cast one array into the type of another, so you'd have to ensure that you create your own array:

public String[] getStrings() {
    String[] result = new String[getSize()];
    copyInto(result);
    return result;
}

answered Feb 18, 2013 at 23:51

beny23

35.1k6 gold badges84 silver badges86 bronze badges

Comments

grepit · Accepted Answer · 2013-02-18 23:57:24Z

1

try this and see if that would work

String[] stringArrayX = Arrays.copyOf(objectArrayX, objectArrayX.length, String[].class);

answered Feb 18, 2013 at 23:57

grepit

22.6k6 gold badges109 silver badges82 bronze badges

Collectives™ on Stack Overflow

Casting from Object[] to String[] gives a ClassCastException

3 Answers 3

1 Comment

Comments

Comments

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Related