我这里有一个程序示例。我有3个面板，如果面板位于panel_1，我想阻止用户按下前一个按钮，并且也停在最后一个面板panel_3的末尾。如果用户位于面板的开头或面板的末尾，是否有任何方法可以禁用按钮？
package cardlayoutalignment;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.border.BevelBorder;
import javax.swing.border.Border;
import javax.swing.border.EmptyBorder;
public class gridbaglayoutdemo {
JFrame Card = new JFrame();
FlowLayout flow = new FlowLayout(FlowLayout.RIGHT,2,2);
Border etch = BorderFactory.createEtchedBorder(Color.white,Color.gray);
Border margin = new EmptyBorder(10,10,10,10);
public static GridBagLayout grid = new GridBagLayout();
GridBagConstraints c = new GridBagConstraints();
final static boolean shouldFill = true;
JPanel container = new JPanel();
JPanel divider = new JPanel();
JPanel bodypanel = new JPanel();
final JPanel buttonpanel = new JPanel();
JPanel panel_1 = new JPanel();
JPanel panel_2 = new JPanel();
JPanel panel_3 = new JPanel();
CardLayout cl = new CardLayout();
public gridbaglayoutdemo(){
Card.setVisible(true);
Card.setSize(605,333);
Card.setTitle("");
Card.setResizable(false);
final Toolkit toolkit = Toolkit.getDefaultToolkit();
Dimension dimension = Toolkit.getDefaultToolkit().getScreenSize();
int x=(int)((dimension.getWidth() - Card.getWidth())/2);
int y=(int)((dimension.getHeight() - Card.getHeight())/2);
Card.setLocation(x, y);
Card.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
bodypanel.setLayout(new BorderLayout());
divider.setLayout(new BorderLayout());
container.setLayout(cl);
cl.show(container, "1");
panel_1.setLayout(grid);
JLabel label_1 = new JLabel("Enter 1:");
label_1.setFont(new Font("Arial", Font.PLAIN, 18));
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 0.5;
c.weighty = 0;
c.gridx = 0;
c.gridy = 0;
c.insets = new Insets(10,10,0,0);
panel_1.add(label_1, c);
JComboBox box_1 = new JComboBox();
box_1.setPreferredSize(new Dimension(200,30));
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 0.5;
c.weighty = 0;
c.gridx = 0;
c.gridy = 1;
c.insets = new Insets(10,10,0,0);
panel_1.add(box_1,c);
JLabel label = new JLabel("");
label.setFont(new Font("Arial", Font.PLAIN, 18));
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 0.5;
c.weighty = 1;
c.gridx = 0;
c.gridy = 2;
c.insets = new Insets(10,0,0,0);
panel_1.add(label, c);
panel_2.setLayout(grid);
JLabel label_2 = new JLabel("Enter 2:");
label_2.setFont(new Font("Arial", Font.PLAIN, 18));
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 0.5;
c.weighty = 0;
c.gridx = 0;
c.gridy = 0;
c.insets = new Insets(10,10,0,0);
panel_2.add(label_2,c);
JTextField text_2 = new JTextField();
text_2.setPreferredSize(new Dimension(200,30));
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 0.5;
c.weighty = 0;
c.gridx = 0;
c.gridy = 1;
c.insets = new Insets(10,10,0,0);
panel_2.add(text_2,c);
JLabel label_22 = new JLabel("");
label_22.setFont(new Font("Arial", Font.PLAIN, 18));
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 0.5;
c.weighty = 1;
c.gridx = 0;
c.gridy = 2;
c.insets = new Insets(10,0,0,0);
panel_2.add(label_22, c);
panel_3.setLayout(grid);
JLabel label_3 = new JLabel("Enter 3:");
label_3.setFont(new Font("Arial", Font.PLAIN, 18));
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 0.5;
c.weighty = 0;
c.gridx = 0;
c.gridy = 0;
c.insets = new Insets(10,10,0,0);
panel_3.add(label_3,c);
JTextField text_3 = new JTextField();
text_3.setPreferredSize(new Dimension(200,30));
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 0.5;
c.weighty = 0;
c.gridx = 0;
c.gridy = 1;
c.insets = new Insets(10,10,0,0);
panel_3.add(text_3,c);
JLabel label_33 = new JLabel("");
label_33.setFont(new Font("Arial", Font.PLAIN, 18));
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 0.5;
c.weighty = 1;
c.gridx = 0;
c.gridy = 2;
c.insets = new Insets(10,0,0,0);
panel_3.add(label_33, c);
buttonpanel.setLayout(new FlowLayout(SwingConstants.RIGHT));
buttonpanel.setBorder(new EmptyBorder(0,10,0,0));
JButton btnBack = new JButton("< Back");
btnBack.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
cl.previous(container);
buttonpanel.repaint();
}
});
btnBack.setFont(new Font("Arial", Font.PLAIN, 20));
btnBack.setFocusable(false);
btnBack.setFocusTraversalKeysEnabled(false);
btnBack.setFocusPainted(false);
btnBack.setBorder(new BevelBorder(BevelBorder.RAISED, Color.BLACK, null, null, null));
btnBack.setPreferredSize(new Dimension(110, 40));
btnBack.setBackground(new Color(224,223,227));
buttonpanel.add(btnBack);
JButton btnNext = new JButton("Next >");
btnNext.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
cl.next(container);
buttonpanel.repaint();
}
});
btnNext.setFont(new Font("Arial", Font.PLAIN, 20));
btnNext.setFocusable(false);
btnNext.setFocusTraversalKeysEnabled(false);
btnNext.setFocusPainted(false);
btnNext.setBorder(new BevelBorder(BevelBorder.RAISED, Color.BLACK, null, null, null));
btnNext.setPreferredSize(new Dimension(110, 40));
btnNext.setBackground(new Color(224,223,227));
buttonpanel.add(btnNext);
final JButton btnCancel = new JButton("Cancel");
btnCancel.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
Window dialog = SwingUtilities.windowForComponent( btnCancel );
dialog.dispose();
}
});
btnCancel.setFont(new Font("Arial", Font.PLAIN, 20));
btnCancel.setFocusable(false);
btnCancel.setFocusTraversalKeysEnabled(false);
btnCancel.setFocusPainted(false);
btnCancel.setBorder(new BevelBorder(BevelBorder.RAISED, Color.BLACK, null, null, null));
btnCancel.setPreferredSize(new Dimension(110, 40));
btnCancel.setBackground(new Color(224,223,227));
buttonpanel.add(btnCancel);
JPanel numberpanel = new JPanel();
numberpanel.setPreferredSize(new Dimension(221,0));
numberpanel.setBorder(new EmptyBorder(10,0,0,10));
numberpanel.setBorder(BorderFactory.createEtchedBorder(Color.white,Color.gray));
numberpanel.setLayout(flow);
JButton button_7 = new JButton("7");
button_7.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
});
button_7.setFont(new Font("Arial", Font.PLAIN, 30));
button_7.setFocusable(false);
button_7.setFocusTraversalKeysEnabled(false);
button_7.setFocusPainted(false);
button_7.setBorder(new BevelBorder(BevelBorder.RAISED, Color.BLACK, null, null, null));
button_7.setPreferredSize(new Dimension(70, 70));
button_7.setBackground(new Color(224,223,227));
numberpanel.add(button_7);
JButton button_8 = new JButton("8");
button_8.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
});
button_8.setFont(new Font("Arial", Font.PLAIN, 30));
button_8.setFocusable(false);
button_8.setFocusTraversalKeysEnabled(false);
button_8.setFocusPainted(false);
button_8.setBorder(new BevelBorder(BevelBorder.RAISED, Color.BLACK, null, null, null));
button_8.setPreferredSize(new Dimension(70, 70));
button_8.setBackground(new Color(224,223,227));
numberpanel.add(button_8);
JButton button_9 = new JButton("9");
button_9.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
});
button_9.setFont(new Font("Arial", Font.PLAIN, 30));
button_9.setFocusable(false);
button_9.setFocusTraversalKeysEnabled(false);
button_9.setFocusPainted(false);
button_9.setBorder(new BevelBorder(BevelBorder.RAISED, Color.BLACK, null, null, null));
button_9.setPreferredSize(new Dimension(70, 70));
button_9.setBackground(new Color(224,223,227));
numberpanel.add(button_9);
Card.add(bodypanel);
bodypanel.add(divider, BorderLayout.WEST);
divider.add(container, BorderLayout.NORTH);
container.add(panel_1, "1");
container.add(panel_2, "2");
container.add(panel_3, "3");
//container.add(panel_4, "4");
//container.add(p5.panel_5, "5");
//container.add(p6.panel_6, "6");
divider.add(buttonpanel, BorderLayout.SOUTH);
bodypanel.add(numberpanel, BorderLayout.EAST);
}
public static void main(String[] args){
//Use the event dispatch thread for Swing components
EventQueue.invokeLater(new Runnable()
{
@Override
public void run()
{
new gridbaglayoutdemo();
}
});
}
}
对不起那么短的工作代码感到抱歉。我已经修剪了一些。这是我能做的最短的。
答案 0 :(得分：3)
“如果用户位于面板的开头或面板的末尾，是否有任何方法可以禁用按钮？”
根据How to Use CardLayout和CardLayout API，没有直接的方法可以做到。
但您可以轻松实现此功能，使用当前卡号保留一个int变量，并检查其值为0（对于第一张卡）或容器的组件计数（对于最后一张卡）。例如：
public class GridBagLayoutDemo { // note code convention!
int currentCard = 0;
Action backAction, nextAction;
...
public GridBagLayoutDemo() {
...
backAction = new AbstractAction("< Back") {
@Override
public void actionPerformed(ActionEvent e) {
currentCard--;
GridBagLayoutDemo.this.evaluateActions();
}
};
nextAction = new AbstractAction("Next >") {
@Override
public void actionPerformed(ActionEvent e) {
currentCard++;
GridBagLayoutDemo.this.evaluateActions();
}
};
JButton btnBack = new JButton(backAction);
...
JButton btnNext = new JButton(nextAction);
...
}
private void evaluateActions() {
backAction.setEnabled(currentCard > 0);
nextAction.setEnabled(currentCard < container.getComponentCount() - 1);
}
...
}
仔细观察CardLayout实施，默认情况下实现此功能非常容易（除非我遗漏了一些内容）：
public class CardLayout implements LayoutManager2,
Serializable {
/*
* This creates a Vector to store associated
* pairs of components and their names.
* @see java.util.Vector
*/
Vector vector = new Vector();
/*
* Index of Component currently displayed by CardLayout.
*/
int currentCard = 0;
...
/*
* Hypothetical implementations
*/
public boolean isDisplayingFirstCard() {
return currentCard == 0;
}
public boolean isDisplayingLastCard() {
return currentCard == vector.size() - 1;
}
}
不知道为什么他们没有提供这样有用的功能。
答案 1 :(得分：2)
查看Card Layout Actions以查看CardLayout的简单扩展名。
它提供＆＃34;下一步＆＃34; 和＆＃34;上一步＆＃34; 操作，您可以使用这些操作创建按钮或菜单项以及操作当您在卡的结尾处开始时，将自动禁用。