Carried throws declarations for RuntimeExceptions

Question

Suppose I have a method or a constructor that uses another method or constructor internally that declares a RuntimeException can be thrown.

// Example:
public MyClass(Object arg) {
    setVar(arg);
    // Not responsible for dealing with the exception
}

public void setVar(Object arg) throws MyRuntimeException {
    if(!isValidArg(arg))
        throw new MyRuntimeException("Got you, evil argument!");
    // Do something
}

In this case the RuntimeException is thrown if for example necessary preconditions are not fulfilled.

Q: Should the wrapping method/constructor declare the same Exception, if it's argument could cause the Exception to be thrown?

Answer 1

It really depends on the context that the code is in. If you want to make something that is self contained, like a Library, you might want to catch the Exception inside the class, just to make the use of your code cleaner.

However if you're making code as part of a project, then I would, as you say, "carry the throws exception" until it doesn't make sense, semantically.

Answer 2

I would declare it if it is not supposed to be handled inside the wrapping method - the same as with checked exceptions.

Anyway good to have such a hint for method even for unchecked exceptions. The client will decide if it needs to be handled.

Answer 3

RuntimeExceptions are thrown without the need to include it in the throws signature for neither of the methods.

You should read this about runtime exception

Answer 4

no, Runtime Exceptions are not checked i.e. compiler does not forces you to deal with them. But as a good programming practice you can handle the exception like

public MyClass(Object arg) {
  try{
    setVar(arg);
}
catch(MyRuntimeException exp){
   // code if exception arises
}