Is “throws Throwable” good practice

Question

In the past I\'d read tons of code with methods like:

public Object doSomething() throws Throwable {
    ...
}

Is it common practice to do

Answer 1

You should not throw Throwable. Here's why.

Throwable is the top of the hierarchy of things that can be thrown and is made up of Exceptions and Errors. Since Errors by definition arise from unsalvagable conditions, it is pointless to include them in your method declaration. That leaves just Exception.

You should declare your method with throws Exception instead.

Note that the narrower the range of throws the better.

Declaring your method to be throws Exception is ok if your method doesn't generate the exceptions, but instead calls other code that is declared as throws Exception and you want exceptions to percolate up the call stack.

If your method is the generating the exception, then declare a narrower range, eg throws IOException, MyProcessingException, etc

Answer 2

It is really debatable matter. Having method throwing too many exceptions will result in lot of error handling code. Some times it is not intended.

But because I don't like too many exception in signature does not mean that Lets use Parent of all exceptions and we are done!! It will not work.

What one can do is categorise exceptions such as BusinessException,ServiceException so that if you have a business rule which says that minimum balance in account can not be less than say 100$ then InsufficientBalance exception will be generated which will be child of BusinessException

so you method will be like

public Object doSomething() throws BusinessException {

 if(!hasMinimumbalance())
  { 
    throw new InsufficientBalance(ErrorCode);
  }
}

What this will do is club related exceptions together and whenever API user wants to detect exception specific error then he can do it, else generic error handling is possible.

The core point here is on the UI you should display to the user that You have run out of balance and you can not withdraw money

You can say on the larger aspect to display human readable form of error it is really necessary to have separation of exceptions.

Answer 3

The only use case I can think of would be for test code like unit tests. But Adam's counterpoint still stands "If so, then it's not good practice. It doesn't provide any useful information to class (method) user."