Tracepoints in Eclipse

Question

There seem to be no support for tracepoints in Eclipse (JDT) debug mode.

This is really a bummer, since you may sometime want to print a lot of debug infomation without cluttering your code with hardcoded println that you are likely to forget later on.

I found a simple workaround for that and wanted to share with SO.

Answer 1

Eclipse supports conditional breakpoints.

All you have to do, is provide it with a boolean expression, and it'll be happy. In this case, a static method that also prints useful stuff as a side effect is fine.

public class TracePointUtils {

  static private Logger logger = org.slf4j.LoggerFactory.getLogger(TracePointUtils.class);

  /** Produce a WARN message in SL4J logger */
  public static boolean trace(String msg, Object ... args) {
    logger.warn(format(msg, args));
    // Do not stop
    return false;
  }
}

Here, I use SL4J as a logger, but a plain println would be fine.

Then, add a breakpoint in your code, and call this static method as the condition:

Et voila, you can enjoy nice traces in your console.

Answer 2

Just for the record, Eclipse Oxygen provides support for tracepoints:

http://www.eclipse.org/oxygen/noteworthy/#conditional-watchpoint

Clicking around in the menu seems tedious, I think it's best to create a key mapping for the Toggle Tracepoint command.