title: an issue with slf4j in a Java application
body: <p>I am trying to config slf4j on Netbeans using Java application(not web).
  I added libraries : </p>
  
  <ul>
  <li>slf4j-log4j12-1.6.4.jar</li>
  <li>slf4j-api-1.6.4.jar</li>
  </ul>
  
  <p>My code likes this:</p>
  
  <pre><code>public class TestLogger {
  
  /**
   * @param args the command line arguments
   */
  public static void main(String[] args) {
      // TODO code application logic here
      Logger logger = LoggerFactory.getLogger(TestLogger.class);
      logger.info("Hello worlds");
  }
  }
  </code></pre>
  
  <p>and I don't have any pom.xml which is mentioned a lot in some guides I read.
  what is it?</p>
  
  <p>My output:</p>
  
  <pre><code>run:
  Failed to instantiate SLF4J LoggerFactory
  Reported exception:
  java.lang.NoClassDefFoundError: org/apache/log4j/Level
  at org.slf4j.LoggerFactory.bind(LoggerFactory.java:128)
  at org.slf4j.LoggerFactory.performInitialization(LoggerFactory.java:108)
  at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:279)
  at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:252)
  at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:265)
  at testlogger.TestLogger.main(TestLogger.java:22)
  Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Level
  at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
  at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
  at java.security.AccessController.doPrivileged(Native Method)
  at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
  ... 6 more
  Exception in thread "main" java.lang.NoClassDefFoundError:       org/apache/log4j/Level
  at org.slf4j.LoggerFactory.bind(LoggerFactory.java:128)
  at org.slf4j.LoggerFactory.performInitialization(LoggerFactory.java:108)
  at org.slf4j.LoggerFactory.getILoggerFactory(LoggerFactory.java:279)
  at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:252)
  at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:265)
  at testlogger.TestLogger.main(TestLogger.java:22)
  Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Level
  at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
  at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
  at java.security.AccessController.doPrivileged(Native Method)
  at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
  at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
  at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
  ... 6 more
  Java Result: 1
  BUILD SUCCESSFUL (total time: 0 seconds)
  </code></pre>
  
  <p>I know I must config  a .xml file so that slf4j could run smoothly.
  but I don't know how and where.</p>
  
  <p>P/s: what is pom.xml? I saw it a lot in some tutorials. </p>