[英]java not displaying jpanel in jframe after button press
我只是在制作一個用戶界面,按下按鈕后我想要它做的就是顯示謝謝...我對此很陌生,但是從我看來沒有錯誤嗎? 我嘗試過在可見的情況下玩耍,但無濟於事...任何幫助都非常感謝
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.GridLayout;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.border.Border;
import javax.swing.JTextField;
import javax.swing.JLabel;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JList;
public class GuiApp1 {
public static void main(String args[]) {
String title = (args.length == 0 ? "CheckBox Sample" : args[0]);
JFrame frame = new JFrame(title);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JPanel panel = new JPanel(new GridLayout(0, 1));
Border border = BorderFactory.createTitledBorder("Pizza Toppings");
panel.setBorder(border);
JLabel label1 = new JLabel("Enter name below:");
panel.add(label1);
JTextField field = new JTextField(20);
panel.add(field);
JCheckBox check = new JCheckBox("Car0");
panel.add(check);
check = new JCheckBox("Car1");
panel.add(check);
check = new JCheckBox("Car2");
panel.add(check);
check = new JCheckBox("Car3");
panel.add(check);
check = new JCheckBox("Car4");
panel.add(check);
JButton button = new JButton("Submit");
final JPanel listPanel = new JPanel();
listPanel.setVisible(false);
JLabel listLbl = new JLabel("Vegetables:");
listPanel.add(listLbl);
button.addActionListener(new ActionListener()
{
@Override
public void actionPerformed(ActionEvent event)
{
listPanel.setVisible(!listPanel.isVisible());
panel.setVisible(!panel.isVisible());
}
});
Container contentPane = frame.getContentPane();
contentPane.add(panel, BorderLayout.CENTER);
contentPane.add(button, BorderLayout.SOUTH);
frame.setSize(300, 300);
frame.setResizable(true);
frame.setVisible(true);
frame.setLocationRelativeTo(null);
}
}
蔬菜面板不出現的原因很簡單:Xou從未將ist添加到contentPane
。
為了使代碼正常運行,您需要在按鈕的ActionListener
中添加/刪除面板:
button.addActionListener(new ActionListener()
{
@Override
public void actionPerformed(ActionEvent event)
{
listPanel.setVisible(!listPanel.isVisible());
panel.setVisible(!panel.isVisible());
if (listPanel.isVisible()) {
contentPane.remove(panel); // Vegetables are visible, so remove the Cars
contentPane.add(listPanel, BorderLayout.CENTER); // And add the Vegetables
} else {
contentPane.remove(listPanel); // Vice versa
contentPane.add(panel, BorderLayout.CENTER);
}
}
});
然后,您需要將ActionListener
移到contentPane
聲明下方,並將其設置為final
。
另外,您應該考慮將不同的復選框放入不同的變量,以便可以讀取它們的狀態。 如果不想掛那么多變量,可以將它們放入數組中。
JCheckBox[] checks = new JCheckbox[5];
checks[0] = new JCheckBox("Car0");
panel.add(checks[0]);
...
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