I am trying to run a code for converting the text to speech

[code]
import javax.speech.*;
import javax.speech.synthesis.*;
import java.util.Locale;

public class HelloWorld {
public static void main(String args[]) {
try {
// Create a synthesizer for English
Synthesizer synth = Central.createSynthesizer(
new SynthesizerModeDesc(Locale.ENGLISH));

// Get it ready to speak
Line 13. synth.allocate();
synth.resume();

// Speak the "Hello world" string
synth.speakPlainText("Hello, world!",null);

// Wait till speaking is done
synth.waitEngineState(Synthesizer.QUEUE_EMPTY);

// Clean up
synth.deallocate();
} catch (Exception e) {
e.printStackTrace();
}
}
}

</code]

When i run this program. I am getting null pointer exception at line 13