Throwing exceptions in Java

Question

I have a question about throwing exceptions in Java, a kind of misunderstanding from my side, as it seems, which I would like to clarify for myself.

I have been read

Answer 1

I'm gonna answer your questions in turn, then add some comments to the end. I'm not an authority on exception handling, but I hope my comments are helpful.

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"Doesn't the first way of handling exceptions does exactly this"?

My answer is yes, as you describe it the first method does operate by throwing and catching an exception in the same method. However, I don't know that try-throw-catch has to work as you describe it.

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"I have read that it is a better practice to throw an exception in one method, and catch it in another method, but this is just one (probably better) way. The other way is also legal and correct, isn't it?"

I agree that catching exceptions from a second method is better, but the first way is legal. Is it correct? well that's for you to decide, it is your code, after all.

For the most part, I agree that it doesn't make sense to throw an exception then immediately catch that exception in the same method. If we do this because the method is particularly long/complex and handling the error using other logic would complicate things more, then I would suggest moving some of this logic to another method and calling that method and catching its exception.

If our code is simpler, then it may be easy to handle the error using code that doesn't consist of throwing an exception.

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My comments:

The try-throw-catch mechanism you mentioned may not need the exception to be thrown in the same method. I would have to read the text you found to be certain, but I would expect that it isn't necessary. If it didn't need the exception to be thrown in the same method, then your exceptions handling strategy is a combination of 1) and 2).

In the combo, one method would use try-throw-catch mechanism to catch an exception thrown by a called method. It seems to me that 1) and 2) should work together to form your exception handling strategy.

Now, maybe someone will come along and give us some wonderful reasons why we might want to throw an exception in the same method. I expect there are some, but to me they seem the exceptions, not the rule.

Cheers, Ed