The paint() Method Swallows RuntimeExceptions

If a RuntimeException is thrown within the paint() method of a Field, the RuntimeException is swallowed! Nothing is ever printed, and there is no indication that an exception was ever thrown (except that the code after the exception does not run).

I have confirmed this on the 4.7.0.75-9530 simulator using the following code:

 protected void paint( Graphics graphics ) {

        if ( true ) {
            throw new RuntimeException( "This text will never show up anywhere." );
        }

        super.paint( graphics );
 }

Symptoms

Sections of the Screen or possibly an entire Field might not paint correctly whereas the rest of the Screen may paint just fine. This is a common behavior when an Exception is thrown and consumed by the framework so the app does not crash.

Workaround

Adding a try/catch block can be expensive, and is probably a bad idea within the paint() method. To work around this problem, we should rely more on null checking than on RuntimeExceptions (such as IllegalArgumentException). If a RuntimeException must be thrown, it is important to print an error message before throwing the exception. Otherwise no record of the exception will be displayed in the log.