java中的语音识别

我想在我的项目中使用语音识别，我找到了这段代码，但是当我运行它时，我收到一个错误：

run: java.lang.NullPointerException
        at newpackage.HelloWorld.main(HelloWorld.java:55)

请问你们中有人能帮我解决这个问题吗？

这是我使用的服务器代码：

package newpackage;

import java.util.logging.Level;
import java.util.logging.Logger;
import javax.speech.*;
import javax.speech.recognition.*;
import java.io.FileReader;
import java.util.Locale;

public class HelloWorld extends ResultAdapter {
  static Recognizer rec;

  // Receives RESULT_ACCEPTED event: print it, clean up, exit
  public void resultAccepted(ResultEvent e) {
    Result r = (Result)(e.getSource());
    ResultToken tokens[] = r.getBestTokens();

    for (int i = 0; i < tokens.length; i++)
      System.out.print(tokens[i].getSpokenText() + " ");

    System.out.println();
    try {
          // Deallocate the recognizer and exit
          rec.deallocate();
    } catch (EngineException ex) {
          Logger.getLogger(HelloWorld.class.getName()).log(Level.SEVERE, null, ex);
    } catch (EngineStateError ex) {
          Logger.getLogger(HelloWorld.class.getName()).log(Level.SEVERE, null, ex);
    }
    System.exit(0);
  }

  public static void main(String args[]) {
    try {
      // Create a recognizer that supports English.
      rec = Central.createRecognizer(
              new EngineModeDesc(Locale.ENGLISH));

      // Start up the recognizer
      rec.allocate();

      // Load the grammar from a file, and enable it
      FileReader reader = new FileReader(args[0]);
      RuleGrammar gram = rec.loadJSGF(reader);

      gram.setEnabled(true);

      // Add the listener to get results
      rec.addResultListener(new HelloWorld());

      // Commit the grammar
      rec.commitChanges();

      // Request focus and start listening
      rec.requestFocus();
      rec.resume();
    } catch (Exception e) {
      e.printStackTrace();
          // System.out.println("the problem");
    }
  }
}

重写

// Create a recognizer that supports English.
      rec = Central.createRecognizer(
              new EngineModeDesc(Locale.ENGLISH));

如下

            SynthesizerModeDesc desc = new SynthesizerModeDesc(
            null,          // engine name
            "general",     // mode name
            Locale.US,     // locale
            null,          // running
            null);         // voice

     synth = Central.createSynthesizer(desc);