Exception Handling

Exception Handling in Generall

1. Whenever you can handle an exception, catch it and handle it.
2. Whenever you cannot handle an exception, don't catch it, but forward it to the caller of the method.
3. Be responsible for your own ressources.

Forwarding Exceptions

Try to wrap the exception into an announced exception:

public void myExample(int i) throws IllegalArgumentException {
  try {
    [...]
  }
  catch(ProprietaryException ex) {
    throw new IllegalArgumentException(ex);
  }
}

Wrap the catched exception into a RuntimeException:

public void myExample() {
  try {
    [...]
  }
  catch(ProprietaryException ex) {
    throw new RuntimeException(ex);
  }
}

RuntimeExceptions

RuntimeExceptions are defined leading to an undefine state of the software.

Handling Ressources

If a ressource is used, the programmer has to ensure, that the ressource is freed afterwards.

If a transaction is used, the programmer has to ensure, that it is closed afterwards. Implementing this is easy within java. Please take the following snippet, which contains the basic elements of this strategy:

tid = kernelUtil.begin();
try {
  [...]
}
finally {
  kernelUtil.clear(tid);
}

(kernelUtil is an instance of the class EquipmentKernelUtil.)

Other Links

• http://community.mywms.de/documentation.item.jsp?oid=5821
• http://java.sun.com/docs/books/tutorial/java/nutsandbolts/exception.html