Coding Conventions for Exceptions

Under normal circumstances don't create your own subclasses of AppException or AppRuntimeException.
Use exception chaining and exception logging when handling serious errors (the definition of "serious" is application-specific).
When writing the text of errors in a message file, be aware of localization issues. Do not write code which simply replaces placeholders with hard-coded literals as shown in Coding Conventions for Exceptions.

Figure 1. Incorrect usage of hard-coded literals

//Check that BankAccount entity exists:
bankAccountKey.accountNumber = argIn.accountNumber;
try {
  bankAccountDtls = bankAccount.read(bankAccountKey);
} catch (RecordNotFoundException rnf) {
  //This is a SERIOUS error
  curam.util.exception.AppException e = new AppException(
                            COOKBOOK.ID_NO_SUCH_ACCOUNT, rnf);
  e.setLoggable(true);   //make sure it gets logged
  e.arg("not found"); // NOT LOCALIZABLE!!!
  throw e;
}