What is a good way to pass useful state information to an exception in Java?

Question

I noticed some confusion initially with my question. I\'m not asking about how to configure a logger nor how to use a logger properly, but rather how to capture all of the infor

Answer 1

I have created a key combination in eclipse for a catch block creation.

logmsg as key and the result will be:

catch(SomeException se){
   String msg = ""; //$NON-NLS-1$
   Object[] args = new Object[]{};

   throw new SomeException(Message.format(msg, args), se);
}

You can put as many informations as you want in the Message like:

msg = "Dump:\n varA({0}), varB({1}), varC({2}), varD({3})";
args = new Object[]{varA, varB, varC, varD};

Or some user information:

msg = "Please correct the SMTP client because ({0}) seems to be wrong";
args = new Object[]{ smptClient };

You should think about using log4j as a logger, so you can print your states where ever you want. With the options DEBUG, INFO, ERROR you can define how many loggings you want to see in your log file.

When you deliver your application you will set the log level to ERROR, but when you want to debug your application you can use DEBUG as default.

When you are using a logger, you only have to print a hand full of information in your exception, because the state of some variables you would print into the log file before you are calling the critical try...catch block.

String msg = "Dump:\n varA({0}), varB({1}), varC({2}), varD({3})";
Object[] args = new Object[]{varA, varB, varC, varD};
logger.debug(Message.format(msg, args));

try{

// do action
}catch(ActionException ae){
    msg = "Please correct the SMTP client because ({0}) seems to be wrong";
    args = new Object[]{ smptClient };

    logger.error(Message.format(msg, args), se);
    throw new SomeException(Message.format(msg, args), se);
}