Applet程序没有在Netbeans中运行

Question

我应该写一个小程序，显示一个可以用滑块调节的温度计。我相信我有GUI，一切都想通了。在JGrasp（我通常使用的）它询问我是否要将其作为applet运行然后一切正常。对于我当前的课程，我的教师希望在NetBeans中完成所有工作并且我没有错误，但是当我运行applet时没有任何反应。非常感谢任何帮助！

package thermometer;

/**
* MTCH_HRTG
*/
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;

public class Thermometer extends JApplet implements ChangeListener {

// Container
private Container contentPane;
// Panels
private JPanel sliderP;
private JPanel displayP;
private JPanel titleP;
//Slider
private JSlider slider;
//Labels
private JLabel title;
private JLabel tempL;
//Textfield
private JTextField temp;

public void init () {
    contentPane = getContentPane();
    contentPane.setLayout (new BorderLayout ());

    // Setting the panels and objects
    titleP = new JPanel ();
    displayP = new JPanel ();
    sliderP = new JPanel ();

    title = new JLabel ("Adjust the slider to change the temperature");
    titleP.add(title);

    // Creates the thermometer
    slider = new JSlider (JSlider.VERTICAL, -50, 120, 70);
    slider.setMajorTickSpacing(10);
    slider.setMinorTickSpacing(5);
    slider.setPaintTicks(true);
    slider.setPaintLabels(true);

    slider.addChangeListener(this);
    sliderP.add(slider);

    temp = new JTextField ("70", 2);
        temp.setEditable(false);
        tempL = new JLabel ("Degrees in Fahrenheit");

    displayP.add(temp);
    displayP.add(tempL);

    //Adding the panels to the content pane
    contentPane.add(titleP, BorderLayout.NORTH);
    contentPane.add(sliderP, BorderLayout.CENTER);
    contentPane.add(displayP, BorderLayout.SOUTH);
}
    public void stateChanged (ChangeEvent e)    {
        int temperature = slider.getValue();
            temp.setText(Integer.toString(temperature));
    }


public static void main(String[] args) {

}

}