In order to compile and run the Hadoop WordCount example in NetBeans, I followed these steps:
  1. Create a new Java project called hadoop.
  2. Copy the src/examples/org/apache/hadoop/WordCount.java to src/hadoop.
  3. Select Run>Set Project Configuration>Customize and change the Main class entry to hadoop.WordCount. Also set the arguments entry to 'input output".
  4. Add the following jar files as libraries: hadoop-0.20.2-core.jar, commons-cli-1.2.jar, commons-logging-1.0.4.jar, commons-httpclient-3.0.1.jar
  5. Add the following method to the WordCount class: 
    static public boolean deleteDirectory(File path) {
        if (path.exists()) {
            File[] files = path.listFiles();
            for (int i = 0; i < files.length; i++) {
                if (files[i].isDirectory()) {
                    deleteDirectory(files[i]);
                } else {
                    files[i].delete();
                }
            }
        }
        return (path.delete());
    }
  6. Add the following lines of code just before the "new Job" line: 
      // delete the output directory.
   WordCount.deleteDirectory(new File(otherArgs[1]));
  7. Create the input directory.
  8. Copy a text file into the input directory.
  9. Press F6 to run the program.
  10. Read the files in the output directory.