Pass classname to method

Question

My programs tend to use a lot of wrapped exceptions (SwingWorker, for instance, wraps all its exceptions in ExecutionException). So, I am trying to write a method that will allow me to check if an exception or any of its causes is an instanceof an exception type, but I don't know how (if it is even possible) to pass JUST a class name as an argument to a method.

So far, I have this:

public static boolean errorOrCausesInstanceOfClass(Throwable e, Class c) { return e != null && (e.getClass().equals(c) || (e.getCause() != null && errorOrCausesInstanceOfClass(e.getCause(), c))); }

But this will only work if e.getClass() is exactly equal to c.getClass(). But I'd like to check using instanceof to catch subclasses as well.

Is there a way to accomplish this?

Class is a raw type and should be parameterized on your method like (Throwable e, Class<?> c) — Mark W
– Mark W, Commented Jan 9, 2014 at 21:27

Claas Wilke · Accepted Answer · 2014-01-09 21:24:27Z

Try use

Class.isAssignableFrom(Class clazz)

http://docs.oracle.com/javase/7/docs/api/java/lang/Class.html#isAssignableFrom(java.lang.Class)

user987339 · Accepted Answer · 2014-01-09 22:44:00Z

4

Look at Class.isAssignableFrom().

edited Jan 9, 2014 at 22:44

user987339

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answered Jan 9, 2014 at 21:23

evanchooly

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Comments

ZhongYu · Accepted Answer · 2014-01-09 22:11:23Z

1

See the handy method Class.isInstance()

 if( ... c.isInstance(e) ...

answered Jan 9, 2014 at 22:11

ZhongYu

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6 Comments

Mike B Over a year ago

I prefer this solution to Class.isAssignableFrom()

ryvantage Over a year ago

@MikeB, is there any particular reason why? Even after reading this question (stackoverflow.com/questions/3949260/…) I am still having trouble understanding why one is preferable over the other

Mike B Over a year ago

@ryvantage, it's mainly a personal preference. The only real advantage that I'm aware of is you don't have to worry about a NullPointerException.

ryvantage Over a year ago

@MikeB, I think then you have the wrong preference. Because with isAssignableFrom you have to invoke the getClass() method of your parameter, which throws a NPE if it is null. isInstance is the method that won't throw a NPE.

Mike B Over a year ago

@ryvantage Yes, I said I preferred this solution (the one in the answer this comment is below), which is c.isInstance(e) for exactly the reason you point out.

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