我的cardlayout的下一个功能工作正常，但前一个不是。就我而言，只是有"layout.previous(_);"在actionPerformed方法体在我的makePanel()方法应该工作，但是当我运行我的程序并单击prev按钮，什么都没有发生。我做错了什么?-
import java.awt.*;
import javax.swing.*;
import java.util.*;
import java.awt.event.*;
public class Temp
{
public static void main (String[] args)
{
new MakeAQuiz();
}
static class MakeAQuiz
{
private JPanel start, base, fields, buttonz, question;
private String [] labels = {"Enter your question: ", "Answer 1: ", "Answer 2: ", "Answer 3: ", "Answer 4: "};
private JButton [] buttons = {new JButton("<<Go back"), new JButton("I'm done"), new JButton("Next>>")};
private JFrame makeFrame;
public MakeAQuiz()
{
start = new JPanel(new CardLayout());
start.add(makePanel(),"1");
makeFrame = new JFrame();
makeFrame.setSize(500,600);
makeFrame.add(start);
makeFrame.setVisible(true);
makeFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public JFrame getJFrame()
{
return makeFrame;
}
public JPanel makePanel()
{
question = new JPanel(new FlowLayout());
fields = new JPanel(new GridBagLayout());
buttonz = new JPanel(new FlowLayout());
base = new JPanel(new BorderLayout());
GridBagConstraints c = new GridBagConstraints();
c.weighty=0.5; //adds padding between the fields vertically
for (int i = 1; i<5; i++)
{
c.gridy++; //puts each field in a seperate line/row
JLabel label = new JLabel(labels[i]);
// c.fill = GridBagConstraints.HORIZONTAL;
fields.add(label,c);
JTextField textField = new JTextField(20);
fields.add(textField,c);
}
final CardLayout layout = (CardLayout)start.getLayout();
buttons[1].addActionListener(new ActionListener() {
// @Override
public void actionPerformed(ActionEvent e) {
buttons[0].setEnabled(false);
buttons[2].setEnabled(false);
// for(Component comp : cardPanel.getComponents()) {
// if(comp instanceof Page) {
// Page page = (Page)comp;
// page.printData();
// }
// }
}
});
buttons[2].addActionListener(new ActionListener()
{
// @Override
public void actionPerformed(ActionEvent e)
{
start.add(makePanel(), String.valueOf(start.getComponentCount() + 1));
layout.next(start);
}
});
buttons[0].addActionListener(new ActionListener()
{
@Override
public void actionPerformed(ActionEvent e)
{
layout.previous(start);
}
});
buttonz.add(buttons[0]);
buttonz.add(buttons[1]);
buttonz.add(buttons[2]);
JLabel l = new JLabel(labels[0]);
JTextField t = new JTextField(30);
question.add(l);
question.add(t);
base.add(question,BorderLayout.NORTH);
base.add(buttonz,BorderLayout.SOUTH);
base.add(fields,BorderLayout.CENTER);
return base;
}
}
}
我没有问题(与您的代码)，一旦我添加了一些额外的组件到start面板。
但是，您将遇到问题，因为您已经将按钮添加到CardLayout中显示的面板中。
一个更好的解决方案是将按钮放在主屏幕的底部，并将其与卡片分开。
您需要维护某种计数器或对当前页面的引用，因为CardLayout不提供任何方法来获取对当前卡的引用。这将允许您启用/禁用下一步/上一页按钮批准…
更新为可运行的示例…
import java.awt.BorderLayout;
import java.awt.CardLayout;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class MakeAQuiz {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
new MakeAQuiz();
}
});
}
private JPanel start, base, fields, buttonz, question;
private String[] labels = {"Enter your question: ", "Answer 1: ", "Answer 2: ", "Answer 3: ", "Answer 4: "};
private JButton[] buttons = {new JButton("<<Go back"), new JButton("I'm done"), new JButton("Next>>")};
private JFrame makeFrame;
public MakeAQuiz() {
start = new JPanel(new CardLayout());
start.add(makePanel(), "1");
makeFrame = new JFrame();
makeFrame.add(start);
buttonz = new JPanel(new FlowLayout());
final CardLayout layout = (CardLayout) start.getLayout();
buttons[1].addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
buttons[0].setEnabled(false);
buttons[2].setEnabled(false);
}
});
buttons[2].addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
int count = start.getComponentCount();
start.add(new JLabel(Integer.toString(count), JLabel.CENTER), Integer.toString(count));
layout.next(start);
}
});
buttons[0].addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
layout.previous(start);
}
});
buttonz.add(buttons[0]);
buttonz.add(buttons[1]);
buttonz.add(buttons[2]);
makeFrame.add(buttonz, BorderLayout.SOUTH);
makeFrame.pack();
makeFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
makeFrame.setVisible(true);
}
public JFrame getJFrame() {
return makeFrame;
}
public JPanel makePanel() {
question = new JPanel(new FlowLayout());
fields = new JPanel(new GridBagLayout());
base = new JPanel(new BorderLayout());
GridBagConstraints c = new GridBagConstraints();
c.weighty = 0.5; //adds padding between the fields vertically
for (int i = 1; i < 5; i++) {
c.gridy++; //puts each field in a seperate line/row
JLabel label = new JLabel(labels[i]);
// c.fill = GridBagConstraints.HORIZONTAL;
fields.add(label, c);
JTextField textField = new JTextField(20);
fields.add(textField, c);
}
JLabel l = new JLabel(labels[0]);
JTextField t = new JTextField(30);
question.add(l);
question.add(t);
base.add(question, BorderLayout.NORTH);
base.add(fields, BorderLayout.CENTER);
return base;
}
}
No。我觉得这样行不通。简单地点击上一个按钮不会带回任何东西。您应该将条目保存在其他地方，并在单击上一个按钮时将它们加载到相应的字段中。