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Difference Between Throw and Throws.

Mahi Ranga
Ranch Hand

Joined: Jan 27, 2011
Posts: 35

what is the difference between throw and throws? and when can i use throw and when can i use throws.
Please tell me.
Advanced thanks for your Answer.

James Hodgkiss
Ranch Hand

Joined: Jan 22, 2004
Posts: 401
Hiya MahiRanga,

Hope that helps!

Stephan van Hulst

Joined: Sep 20, 2010
Posts: 3720

You use throws in a method signature to indicate that a method is capable of throwing a particular exception. Any code calling this method will have to deal with the possibility that that particular exception can occur.

The throw keyword is used to actually throw an exception. It can be used wherever you can place a statement.


In James' above example, any code that calls checkString() will have to deal with the fact that it *can* throw an exception, and checkString() actually throws an exception if the argument is null.
fred rosenberger
lowercase baba

Joined: Oct 02, 2003
Posts: 11718

"throw" is a command. "Mahi, throw the ball". I am telling you to do something.

"throws" is used to describe something. "Mahi throws a curveball, a fastball, and a slider". I'm telling someone what you can do (or will potentially do in the future).

In java, 'throws' is used to tell the compiler what kind of exceptions a method might pass back up to the caller.

"throw" is used to tell the JVM "hey, you need to send this up to the caller NOW".

There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors
Campbell Ritchie

Joined: Oct 13, 2005
Posts: 42199
To the Batmobile . . . er . . . Java™ Tutorials!
Vas Miriyala
Ranch Hand

Joined: Sep 14, 2009
Posts: 114

Nice explanation guys,thanks for all your answers.
Campbell Ritchie

Joined: Oct 13, 2005
Posts: 42199
You're welcome
It is sorta covered in the JavaRanch Style Guide.
subject: Difference Between Throw and Throws.