Question

I’m a fairly new to Java and to programming, so excuse me if this is a stupid question.

I want to create a method exceptionchecker that does this

public void exceptionchecker(Object check){
    if(check.size() == 0 && some_other_stuff) throw new IllegalArgumentException();
}

The problem is that the object passed might be a list or a string. So depending on the case I need to either use .length or .size().

Is there any easy way to do this, or am I better off creating two seperate methods?

EDIT: If it’s relevant, the list would be of type String as well.

Answer 1

You could use instanceof to do some checks, and it is reliable, but it doesn’t leave it self as open to extension, or clarity.

The reason for this is

• If you’re checking something other than a list or a String, you should know about it at compile time
• As you add more checks, it’s going to cause a giant check method that will get tough to maintain.

Using two methods is most appropriate.

public void exceptionCheck(String s) {
    if(s.length() == 0) throw new IllegalArgumentException();
}

public void exceptionCheck(List<?> l) {
    if(s.isEmpty()) throw new IllegalArgumentException();
}