好的，我将发布这三个类的代码，因为时间不太长。
package guiDemonstration;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class TabbedGUI {
//create fields
private JFrame frame;
private JTabbedPane tabbedPane;
//make the following three labels public for access in the GUIEngine class
private JLabel comboLabel;
private JLabel sliderLabel;
private JLabel radioLabel;
private JSlider slider;
private JComboBox combo;
private JPanel comboPanel, sliderPanel, radioPanel;
private String []comboArray;
private JRadioButton radio, radio1, radio2;
private ButtonGroup buttonGroup;
private String comboText = "Please Make a Choice";
private String sliderText = "Move the Slider";
private String radioText = "Choose a Radio Button";
//Create field to hold GUIEngine Class
GUIEngine engine;
// empty constructor
public TabbedGUI(){
}
//method used to construct the gui
private void makeFrame(){
//create the Frame
frame = new JFrame("Example of a Tabbed GUI");
//set the initial size of the frame in pixels
frame.setSize(500, 200);
//add the frame to the contentPane
Container contentPane = frame.getContentPane();
//create an instance of the GUIEngine class
engine = new GUIEngine();
//create an array of size 3 to be used as dropdown values in the combobox
comboArray = new String[3];
//initialise the array
comboArray[0] = "First Choice";
comboArray[1] = "Second Choice";
comboArray[2] = "Third Choice";
//create instance of JComboBox and add array
combo = new JComboBox(comboArray);
//create instance of JSlider
slider = new JSlider();
//creat instance of Button Group
// this ButtonGroup will hold the individual radio buttons
buttonGroup = new ButtonGroup();
radio = new JRadioButton();
radio1 = new JRadioButton();
radio2 = new JRadioButton();
//create instances of JPanel
comboPanel = new JPanel();
sliderPanel= new JPanel();
radioPanel = new JPanel();
//create flowlayout for comboPanel
comboPanel.setLayout(new FlowLayout());
//create instances of labels
comboLabel = new JLabel(comboText);
sliderLabel=new JLabel(sliderText);
radioLabel = new JLabel(radioText);
//add radio buttons to the group
buttonGroup.add(radio);
buttonGroup.add(radio1);
buttonGroup.add(radio2);
//add a border to the button group
//begin creation of the tabbed GUI and add to contentPane
tabbedPane = new JTabbedPane();
contentPane.add(tabbedPane);
frame.add(tabbedPane);
//add instances of JPanel to each tab
tabbedPane.addTab("Combo Box", comboPanel);
tabbedPane.addTab("Slider", sliderPanel);
tabbedPane.addTab("Radio", radioPanel);
//add components to each JPanel of each tab
comboPanel.add(combo);
comboPanel.add(comboLabel);
sliderPanel.add(sliderLabel);
radioPanel.add(radioLabel);
sliderPanel.add(slider);
radioPanel.add(radio);
radioPanel.add(radio1);
radioPanel.add(radio2);
//set a border around the Slider
slider.setBorder(
BorderFactory.createMatteBorder(1, 1, 1, 1, Color.BLUE));
// call the method to add the listeners to each component
addListeners();
//by default the frame is set to invisible. Set the frame to visible
frame.setVisible(true);
}
/**
* This method adds listeners to each component
*/
public void addListeners(){
//add actionListeners to each component
combo.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
engine.useCombo();
}
});
slider.addChangeListener(new ChangeListener(){
public void stateChanged(ChangeEvent e){
engine.useSlider();
}
});
radio.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
engine.useRadioButtons();
}
});
radio1.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
engine.useRadioButtons();
}
});
radio2.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
engine.useRadioButtons();
}
});
}
/*
* The following three methods set the text for each
* label on the three individual tabs.
* These methods are called from the GUIEngine Class.
*/
//set the text on the comboLabel
public void setComboLabel(){
String updatedComboText = (String)combo.getSelectedItem();
comboLabel.setText(updatedComboText);
//System.out.println("You selected" + comboText);
}
//set the text on the sliderLabel
public void setSliderLabel(){
sliderLabel.setText("You've moved the slider!");
}
//set the text on the radioLabel
public void setRadioLabel(){
System.out.println("You've selected a radio button!");
}
/**
* This method is used to begin execution of the program
*/
public void runProgram(){
makeFrame();
}
}
第2类：
package guiDemonstration;
public class GUIEngine {
TabbedGUI tg;
//constructor
public GUIEngine(){
tg = new TabbedGUI();
}
public void useCombo(){
//System.out.println("You Used the Combo Box");
tg.setComboLabel();
}
public void useSlider(){
tg.setSliderLabel();
}
public void useRadioButtons(){
//System.out.println("You clicked a radio button");
tg.setRadioLabel();
}
}
而只是主要方法：
package guiDemonstration;
public class Controller {
/**
* #This is the main method where program execution begins
* @param args
*/
public static void main(String[] args) {
TabbedGUI tg = new TabbedGUI();
tg.runProgram();
}
}
JCombobox和JSlider会导致运行时错误。代码可以编译，但是当我移动JSlider或在JComboBox上选择一个项目时，程序崩溃。
有任何想法吗？
GF
最佳答案
您的GUIEngine正在创建自己的TabbedGUI实例，而不是使用您在main方法中创建的实例。
如果您需要保留GUIEngine类，建议在makeFrame中执行此操作
引擎=新的GUIEngine（this）;
然后更改GUIEngine构造函数以将TabbedGUI作为参数。也可以使实例变量最终化。