[SOLVED] Throw exception in optional in Java8

Throw exception in optional in Java8

There is a method get(sql) (I can not modify it). This method returns MyObjects and it has to be in try catch block because JqlParseException is possible there. My code is:

String sql = something;
try{
   MyObject object = get(sql);
} catch(JqlParseException e){
   e.printStackTrace();
} catch(RuntimeException e){
   e.printStackTrace();
}

I want to remove try catch and use Optional class, I tried:

MyObject object = Optional.ofNullable(get(sql)).orElseThrow(RuntimeException::new);

but IDE force there try catch too. And for:

MyObject object = Optional.ofNullable(get(sql)).orElseThrow(JqlParseException::new));

is an error (in IDE) The type JqlParseException does not define JqlParseException() that is applicable. Is there any way to avoid try catch blocks and use optional?

Solution

Optional is not intended for the purpose of dealing with exceptions, it was intended to deal with potential nulls without breaking the flow of your program. For example:

 myOptional.map(Integer::parseInt).orElseThrow(() -> new RuntimeException("No data!");

This will automatically skip the map step if the optional was empty and go right to the throw step -- a nice unbroken program flow.

When you write:

 myOptionalValue.orElseThrow(() -> new RuntimeException("Unavailable"));

... what you are really saying is: Return my optional value, but throw an exception if it is not available.

What you seem to want is a way to create an optional (that instantly catches the exception) and will rethrow that exception when you try using the optional.