How to write a java code in an activity?

Pega is built so you can do almost everything with rules, but sometimes an activity needs a few lines of Java. The Java step method is how you add them.

How to add Java to an activity

1. Open the activity and add a step.
2. In the Method column, choose Java.
3. Click the gear or arrow icon next to the step to open the Java editor.
4. Type the code and save. Pega compiles it when you save the rule.

The variable you use most: tools

Inside a Java step you get a tools object that gives you access to the current thread and the clipboard. For example, to read a property from a named page:

ClipboardPage page = tools.findPage("pyWorkPage");
String id = page.getString("pyID");
log.infoForced("Working on case " + id);

Notice that the property name has no leading dot when you use the Java API. Other common calls are page.putString("Status", "Open") to set a value and tools.getPrimaryPage() to get the page the activity is running on.

A worked example

A bank needs to build a reference number that combines the branch code, the year and a padded sequence number, for example BR12-2026-000457. A data transform can do most of it, but the padding is easier in Java:

ClipboardPage work = tools.getPrimaryPage();
String branch = work.getString("BranchCode");
int seq = Integer.parseInt(work.getString("Sequence"));
String ref = branch + "-" + java.time.Year.now() + "-" + String.format("%06d", seq);
work.putString("ReferenceNumber", ref);

Guardrails: use it sparingly

• Pega's guardrails warn against custom Java. Use it only when no out-of-the-box method or function does the job.
• Prefer a function rule if the same code is needed in several places, so it is written once and tested once.
• Custom Java is harder to read, harder to upgrade, and skips the rule-level tracing you get from normal steps.
• Never put secrets, long-running loops or direct JDBC calls in a Java step.

Interview tip

The interviewer wants to hear that you know how, and also that you know when not to. Say: "You use the Java method, but I would first look for a standard method or a function, because guardrails discourage custom Java." Continue with the Activity label.