java - When to throw specific exception and when to output error to console using system.out

Question

I was designing an oop model where I got confused between throwing exception and outputting it through system.out using if else I was doing like

public void fun(int n) {
if(n<0){
    System.out.println("n less than 0");
}
}

I could have also done like

public void fun(int n) throws InvalidNumberException{
if(n<0){
    InvalidNumberException("n less than 0");
}
}

Which is the good way to actually do that. Should I throw exception and catch it or just use if else to output.

question from:https://stackoverflow.com/questions/65859058/when-to-throw-specific-exception-and-when-to-output-error-to-console-using-syste

Answer 1

Throwing an exception is meant to be handled by the caller. Make a custom checked exception for the situation you are in and wrap important information in that checked exception so that the caller can handle it.

If the user is supposed to input something more appropriate and can respond to the system, then print out the error and give the user the ability to correct his input data.

If the system can continue to work correctly; however you wish to track some errors that might be unforeseen, you may log the error to correct the error in future releases.