ClassCastException in Java

Question

I'm getting a ClassCastException in the below code, which doesn't make much sense to me, as targetObject is a Comparable and current is a ToBeFound. Where are the Integer and String coming from?

ToBeFound origin = new ToBeFound();
public ToBeFound findWrapper(Comparable targetObject)
{
    return find(origin, targetObject);
}

private ToBeFound find(ToBeFound current, Comparable targetObject)
{
    if (current == null)
        {
        return null;
        }

    System.out.println(targetObject.compareTo(current.getValue()));
     // Exception in thread "main" java.lang.ClassCastException: 
     // java.lang.Integer cannot be cast to java.lang.String

    return new ToBeFound();
}

//body of main() that calls the methods
master.find( (Comparable) scanner.next()); 
   // Scanner is a java.util.Scanner scanning System.in

Alex Nikolaenkov · Accepted Answer · 2011-03-10 07:07:35Z

1

As compareTo javadoc states:

ClassCastException - if the specified object's type prevents it from being compared to this object.

It seems that your target is of a String type which is Comparable<String> and current.getValue() returns an object of Integer type.

You can try to do String.valueOf(current.getValue) if it works ok then I'm right. :)

answered Mar 10, 2011 at 7:07

Alex Nikolaenkov

2,54520 silver badges28 bronze badges

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

Comments

lindsten · Accepted Answer · 2011-03-10 07:07:49Z

0

private ToBeFound find(TreeNode current, Comparable targetObject)

Looks like current is a TreeNode...

answered Mar 10, 2011 at 7:07

lindsten

881 silver badge6 bronze badges

1 Comment

Anonymous Over a year ago

Oh, no, sorry. That was part of the anonymoization of the code that I hadn't caught.

Piyush Mattoo · Accepted Answer · 2011-03-10 07:12:33Z

0

System.out.println(target.compareTo(current.getValue()));

Return type of compareTo is int, so you can convert your primitive int to String using

System.out.println(Integer.toString(target.compareTo(current.getValue())));

What is the type of target? Seems like you are comparing String against Integer.

answered Mar 10, 2011 at 7:12

Piyush Mattoo

16.2k6 gold badges50 silver badges56 bronze badges

Comments

Stephen C · Accepted Answer · 2011-03-10 07:19:54Z

0

If your sample code is reflects what you are actually running then:

System.out.println(target.compareTo(current.getValue()));

Your code does not show the declaration for target, but the exception message implies that it must be String. (You show use the declaration for targetObject ... but that's not what the code is actually using!!)
Your code doesn't show the declaration for the ToBeFound.getValue() method ... but the exception message implies that it must be Integer.
The String.compareTo(Object) throws a CCE if the parameter object is not a String.

answered Mar 10, 2011 at 7:19

Stephen C

723k95 gold badges849 silver badges1.3k bronze badges

Collectives™ on Stack Overflow

ClassCastException in Java

4 Answers 4

Comments

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Comments

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related