Handling Runtime exception in Java

Question

I have the following piece of code

 try{//do something
 }
 catch (Exception e) {
 log.error(e, e);
 if (e instanceof RuntimeException) {
 throw (RuntimeException) e;
 } else {
 throw new RuntimeException(e);
 }
 }

the findbugs stataic analysis tool throws this warning on it

instanceof will always return true for all nonnull values in methodX, since all RuntimeException are instances of RuntimeException

what i dont understand is that its Exception which is being caught and not the RuntimeException, so why this warning ?

Answer 1

Perhaps, the // do something code does not throw any checked exception, so the only exceptions you can get in your try-block are unchecked ones (subclassing RuntimeException).

Answer 2

You could also try following code. This will be better to read and maintain.

try{//do something
}
catch (RuntimeException e) {
 throw e;
} 
catch (Exception e) {
 throw new RuntimeException(e);
}

Answer 3

Probably there is no methods that throws not RuntimeException in "try" part. Therefore, you can use construction

catch(RuntimeException e)
{
 //Do something
}

Answer 4

Try http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/base/Throwables.html#propagate%28java.lang.Throwable%29. It does exactly what you want. Today I did the replacement for the same reason (findbugs warning), also looked the source of this method.