How do I start to debug my own Apex code?

Here is how I debug my issues. In most cases I would only make it to step 2 before I solve my problem.

Step 1: Explain it to your Rubber Duck

I try explain what my code is doing to my rubber duck. A lot of the time I figure out the problem when I'm explaining the code to someone else. (If exceptions are involved, take a look at your code at the line numbers reported and consider what could have generated the exception.)

Step 2: System Debugs

Debug log recording in Setup is turned on for your User via: Setup > Monitoring > Debug logs. See here for more information.

I would place temporary debug statements such as System.Debug('>>>> the value of x is ' + x); within my code to make sure that the code is executing the way I think its working. Individual SObjects, Maps of SObjects and Lists of SObjects can all be appended and that shows you all populated SObject fields.

The >>>> is a unique string that usually doesn't appear anywhere else in the log files. This allows me to quickly find my debug output. (Logs are truncated after 2M bytes of output - there are work-arounds for this.)

Step 3: Use the Developer Console

The Developer Console is a great tool for debugging. You do the following things (and more) with the developer console

• View Logs. This is another way of viewing debug output.
• Execute SOQL. This can be used to verify that the SOQL in your code is returning the correct information
• Execute Anonymous. Apex code can be run directly from the dev console
• Checkpoints can be added in the code (maximum of 5 per class), which will allow you to stop the code executing and to see variable information.

See Josh Kaplans YouTube video for more info on the dev console

Step 4: Create a Unit Test

A unit test is a great way to figure out what is going on with a piece of code. It allows you to:

• Execute your code in an environment with no other data
• Create test data that you can use over and over again.
• Use asserts to check your code e.g. System.assert(contacts.size() > 0); or System.assertEquals(expectedX, actualX);

Step 5: Take a break

I find myself getting frustrated when I have been looking at the same problem for a long period of time. This does not help solve the problem, it can actually make it harder to clearly see what is going on in the code. Take a break for a while and you may find that when you look at the problem again it makes more sense.

Step 6: Ask for help

If you have done all the steps above and reached this point then you most likely need help. This is where a colleague or stack exchange come in. Make sure when asking a question that you clearly state your problem, provide enough information to make it understandable to others and if you are providing a code sample make sure that it is formatted and easy to read.

I use following techniques:

1) Developer console : Go to [User Name] -> Developer Console. It will open a popup for you where you can run your code, run SOQL and monitor debug logs of executed code.

2) Debug Logs: Sometimes jobs are executed in the background and so monitoring from the developer console becomes difficult. In such cases, we can use Setup -> Monitor -> Logs -> Debug Logs to monitor logs. Also, you can monitor at the user/class/trigger level and filter by log level to get to reduce noise from log.

3) Send email you can send email from apex code to notify the status of log output when log is truncated due to huge size.

4) Log object(Custom object) you can create a custom object to insert the log status as a new record based on custom setting. This is very useful if you have a managed package and customer face any intermediate issue. In such cases you can set the custom setting for that customer and check the records log object to see what was causing the issue.

5) anonymous block you can use anonymous block to debug/execute specific code and verify if its working fine.

Here are some helpful reference links :

http://help.salesforce.com/apex/HTViewHelpDoc?id=code_system_log.htm

https://help.salesforce.com/HTViewHelpDoc?id=code_debug_log.htm&language=en_US

I've added an Apex debugger to Illuminated Cloud that allows you to step through code, see variable values, etc. It uses information from debug logs and checkpoints to "replay" the executed process, and it's tightly integrated into other IDE features such as unit test execution, anonymous Apex, and the integrated log viewer.

For small-to-medium processes, the experience is very similar to an interactive debugger. For larger processes that would exceed the maximum debug log size, it still allows you to stop at registered checkpoints and review heap dump and action script results in the IDE.

You can find out more here:

http://www.illuminatedcloud.com/home/offlinedebugger

And here's a short video showing it in use:

https://youtu.be/NVxUq-CUN8A