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Handling error before catch/finally block when necessary?

Khuma Chhakchhuak
Ranch Hand

Joined: Nov 30, 2012
Posts: 37

Hi all,

When situation arises such that a client requires to handle an exception before executing the catch() or finally block, how do we handle errors? From within the try block itself?

Thanks and eagerly waiting to see some reply.
Mike Simmons
Ranch Hand

Joined: Mar 05, 2008
Posts: 3016
    
  10
You can't, really. Unless you can test for an error condition before you even call the method. For example, if there's a chance that a reference is null, don't call ref.method() without first checking if ref is null:
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 39044
    
  23
To go on from what MS said: that sort of thing is using Exceptions for flow control. In fact, you would be using the Exceptions as a substitute for if statements, which is by no means good design.
Vinod Tiwari
Ranch Hand

Joined: Feb 06, 2008
Posts: 459
    
    1
Are you asking about nested try-catch block? If not, then like Mike and Campbell explained it would not be a wise idea/design to put multiple checks to avoid the exception.


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Mike Simmons
Ranch Hand

Joined: Mar 05, 2008
Posts: 3016
    
  10
Campbell Ritchie wrote:To go on from what MS said: that sort of thing is using Exceptions for flow control. In fact, you would be using the Exceptions as a substitute for if statements, which is by no means good design.

Um, I wasn't talking about using exceptions for flow control at all. I was talking about the opposite, using flow control to prevent exceptions. And I don't think anything that the original poster talked about implied using exceptions for flow control. Than again, I'm not sure what the original poster meant, if it wasn't what I said, so maybe they could explain the goal better.

Vinod Tiwari wrote:like Mike and Campbell explained it would not be a wise idea/design to put multiple checks to avoid the exception.

That sounds like the opposite of what I said.
Campbell Ritchie
Sheriff

Joined: Oct 13, 2005
Posts: 39044
    
  23
I must have been un‑clear. I meant that throwing an catching Exceptions is akin to using exceptions for flow control. I thought that was what OP was asking about.
What you showed is, as you said, the opposite. Using the if (obj == null)… test is a way to prevent exceptions.
 
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