Exception Handling

jameswest

Hi I was just wondering 2 things: 1. Is there a list of supported exception types? I'm wanting to wrap some int parsing in a try catch 2. Very general question I know but just wondering what people would "usually" do exception reporting/handling wise for notification purposes?

jeremydouglass

@jameswest -- you said:

I'm wanting to wrap some int parsing in a try catch

Without seeing your code (which you can share if you like) you probably want NumberFormatException. Here is a Java discussion that might be comparable to your Processing case:

• http://stackoverflow.com/questions/6456219/java-checking-if-parseint-throws-exception

In Processing, catch uses Java built-in exceptions. You can see this from the catch reference documentation

• https://processing.org/reference/catch.html

The catch keyword is used with try to handle exceptions. Sun's Java documentation defines an exception as "an event, which occurs during the execution of a program, that disrupts the normal flow of the program's instructions." [...] exception: the Java exception that was thrown

Here is a general tutorial on Java exceptions and a list of the builtin exceptions:

• https://www.tutorialspoint.com/java/java_exceptions.htm
• https://www.tutorialspoint.com/java/java_builtin_exceptions.htm

jameswest

Thanks Jeremy most appreciated.. how much of Java is supported in Processing?

jeremydouglass

@jameswest --

The vast majority of Java is supported in Processing -- which is run through a pre-processor to be converted into Java when a sketch is built. You may import standard Java libraries, include pure Java tabs, and even write Processing sketches in full IDEs like Eclipse or Netbeans (with the proper setup and configuration).

Every Processing sketch is actually a subclass of the PApplet Java class which implements most of the Processing language's features.

When programming in Processing, all additional classes defined will be treated as inner classes when the code is translated into pure Java before compiling. This means that the use of static variables and methods in classes is prohibited unless you explicitly tell Processing that you want to code in pure Java mode.

-- https://en.wikipedia.org/wiki/Processing_(programming_language)

Example past discussion:

• https://forum.processing.org/two/discussion/11632/whats-the-difference-between-processing-s-java-and-real-java

GoToLoop

This means that the use of static variables and methods in classes is prohibited unless you explicitly tell Processing that you want to code in pure Java mode.

We can use static members in a nested class in a ".pde" file as long as we declare it static as well. L-)

Another way to get static members in nested classes is via extends.

Notice also that inner classes can actually have static final fields declared inside it, as long as they're initialized w/ known compile-time constants! :-bd

1. http://Docs.Oracle.com/javase/specs/jls/se8/html/jls-15.html#jls-15.28
2. https://Community.Oracle.com/thread/1252993

Lord_of_the_Galaxy

Or, you can just catch the base class, Exception.

try{
  //CODE
}catch(Exception e){
  System.err.println(e.getLocalisedMessage());//maybe a Z instead of an S in Localised
  //e.printStackTrace()//if you want
}