contents/using-lttng/instrumenting/java-application/jul.md

   1 ---
   2 id: jul
   3 since: 2.4
   4 ---
   5
   6 Here's an example of tracing a Java application which is using
   7 **`java.util.logging`**:
   8
   9 ~~~ java
  10 import java.util.logging.Logger;
  11 import org.lttng.ust.agent.LTTngAgent;
  12
  13 public class Test
  14 {
  15     private static final int answer = 42;
  16
  17     public static void main(String[] argv) throws Exception
  18     {
  19         // create a logger
  20         Logger logger = Logger.getLogger("jello");
  21
  22         // call this as soon as possible (before logging)
  23         LTTngAgent lttngAgent = LTTngAgent.getLTTngAgent();
  24
  25         // log at will!
  26         logger.info("some info");
  27         logger.warning("some warning");
  28         Thread.sleep(500);
  29         logger.finer("finer information; the answer is " + answer);
  30         Thread.sleep(123);
  31         logger.severe("error!");
  32
  33         // not mandatory, but cleaner
  34         lttngAgent.dispose();
  35     }
  36 }
  37 ~~~
  38
  39 The LTTng-UST Java agent is packaged in a JAR file named
  40 `liblttng-ust-agent.jar` It is typically located in
  41 `/usr/lib/lttng/java`. To compile the snippet above
  42 (saved as `Test.java`), do:
  43
  44 <pre class="term">
  45 javac -cp /usr/lib/lttng/java/liblttng-ust-agent.jar Test.java
  46 </pre>
  47
  48 You can run the resulting compiled class like this:
  49
  50 <pre class="term">
  51 java -cp /usr/lib/lttng/java/liblttng-ust-agent.jar:. Test
  52 </pre>
  53
  54 <div class="tip">
  55 <p>
  56     <span class="t">Note:</span><a href="http://openjdk.java.net/" class="ext">OpenJDK</a> 7
  57     is used for development and continuous integration, thus this
  58     version is directly supported. However, the LTTng-UST Java agent has
  59     also been tested with OpenJDK 6.
  60 </p>
  61 </div>