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

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