Stop sound with button event

I have code for sound that loops and plays on my GUI contained in the main class. Main class code:

public class SoundTest {
public static Clip clip;
public static Mixer mixer;
/**
 * @param args the command line arguments
 */
public static void main(String[] args) {
    // TODO code application logic here

    StartGUI GUI = new StartGUI();
    GUI.setVisible(true);

     Mixer.Info[] mixInfos = AudioSystem.getMixerInfo();
     mixer = AudioSystem.getMixer(mixInfos[0]);

    DataLine.Info dataInfo = new DataLine.Info(Clip.class, null);
    try{
        clip = (Clip)mixer.getLine(dataInfo);
    }
    catch(LineUnavailableException l){
        l.printStackTrace();

    }

    try{
        URL soundURL = Main.class.getResource("/soundtest/8-Bit-Noise-1.wav");
        AudioInputStream audioStrim = AudioSystem.getAudioInputStream(soundURL);
        clip.open(audioStrim);
    }
    catch(LineUnavailableException l){
        l.printStackTrace();
    }
    catch(UnsupportedAudioFileException e ){
        e.printStackTrace();
    }
    catch (IOException i){
        i.printStackTrace();
    }
    clip.start();
    do{
        System.out.println(clip.isActive());
        try{
            clip.loop(Clip.LOOP_CONTINUOUSLY);
            Thread.sleep(50);

        }
        catch(InterruptedException ie){
            ie.printStackTrace();
        }
    }while(clip.isActive());


}

public void stop() {
    clip.stop();
}   

}

In my JFrame class I want to make a button event that will stop the sound, I have tried to make a stop() method in the main class to use it in the button but so far it is not working.

JFrame code:

public class StartGUI extends javax.swing.JFrame {

SoundTest q; 

/**
 * Creates new form SoundTestGUI
 */
public StartGUI() {
    initComponents();
}



private void SoundBtnActionPerformed(java.awt.event.ActionEvent evt) {                                         
    // TODO add your handling code here:
    q.stop();
}                                        

/**
 * @param args the command line arguments
 */
public static void main(String args[]) {


    /* Create and display the form */
    java.awt.EventQueue.invokeLater(new Runnable() {
        public void run() {
            new StartGUI().setVisible(true);
        }
    });
}