Java Debugging Tips

Add Debug Messages

To debug a Java class:

• Add messages to the debug log to trace code execution:

Logger.info("message text", "message type");

(The message type can be used for searching, when needed. Using the class name works pretty well.)

• Examine the contents of a hashmap or list:

Parameters params;

...

Logger.info("params: " + params, "message type");

or pretty=print the string by substituting linebreaks for the comma-separators:

Logger.info("params: " + params.toString().replace(",","\n"), "message type");

• Open the debug log in a separate page:

• Go to > Developer Resources > Debug Log
• After running the code, refresh the page by clicking Debug Log in the sidebar.

• Display a note at the top of the user's page:

Functions.showMessage("message text");

• Abort processing and display an error message:

Functions.throwException("message text");

Learn more:

• See the Class Template for code that uses many of those techniques.

Invoke a Method from a Macro or Rule

The Unit Test Framework is great for automated testing of Java methods, but note that database changes don't persist. That's a highly desirable feature in a test harness, but it means you can't run a test and then look for changes interactively, in the GUI.

To view changes interactively, the code can be launched using a Macro or a Rule. For example:

• Open the object and create a macro that invokes a method. Then, when viewing a record, select the macro from the list of Actions.
• Use an Event Rule that runs when a record is added. (As a precaution, you can set up a condition so that the rule is triggered only when some flag is set.)

Note: There are subtle differences in the parameters available in the different contexts. Learn more: Incoming Method Parameters

Set up a "Debug Mode"

To ensure that your rule fires only when you are actively debugging, you can add a "Debug" flag to the User object, set the default to false, and then set it to true for yourself. The condition add-record Rule condition can then test for Owner.Debug equals true.

Or, more simply, change the value of your title field to "Developer", and then set the Rule condition to Owner.Title equals Developer. Anyone who creates a record is automatically its owner, so anyone who has the title "Developer" will execute the method when they add a record.

Use a JSP Page to Test a Code Fragment

To test a code fragment, you can create a JSP Page.

The page need not have anything on it but the tags needed to embed the code:

<syntaxhighlight lang="java" enclose="div">

<%

  ...your code goes here...

%> </syntaxhighlight>

You can create Test.jsp for example, and visit https://{yourDomain}/networking/pages/Test.jsp to execute the code.

Use the Unit Test Framework

Use the Unit Test Framework to add unit tests to your Java classes.