FlowLayoutパネル内で 2 つのパネルを重ね合わせようとしているアプリケーションがありますBorderLayout。ただし、それを行うと、どちらのパネルも表示されません。
これらのパネルを積み重ねる前のフォームは次のようになります。
しかし、それらを積み重ねると、次のようになります。
SSCCE を使用する場合、問題の原因となる行は次のとおりです。
pane.add(textAreaPanel, BorderLayout.CENTER);
したがって、その行をコメントアウトすると、フォームは少なくとも最初のパネルを表示します。
SSCCE
個別指導電卓
package tutoringcalculator;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.*;
import javax.swing.*;
public class TutoringCalculator extends JFrame {
FlowLayout layout = new FlowLayout(FlowLayout.LEFT);
public TutoringCalculator(String name) {
super(name);
}
public void addComponentsToPane(final Container pane) {
final JPanel contentPanel = new JPanel();
contentPanel.setLayout(layout);
final JPanel textAreaPanel = new JPanel();
textAreaPanel.setLayout(layout);
final JPanel buttons = new JPanel();
buttons.setLayout(new FlowLayout(FlowLayout.RIGHT));
contentPanel.add(new JLabel("Session Minutes:"));
JTextField txt = new JTextField(10);
txt.setName("sessionMinutes");
txt.addFocusListener(new DecimalFieldFocusListener(new IValidDecimalValue() {
@Override
public boolean callback(String val) {
return ApplicationState.getInstance().setCurrentSessionMinutes(val);
}
}));
contentPanel.add(txt);
// setup the default border
ApplicationState.getInstance().setDefaultTextFieldBorder(txt.getBorder());
contentPanel.add(new JLabel("Earnings:"));
txt = new JTextField(10);
txt.setName("earnings");
txt.addFocusListener(new DecimalFieldFocusListener(new IValidDecimalValue() {
@Override
public boolean callback(String val) {
return ApplicationState.getInstance().setCurrentEarnings(val);
}
}));
contentPanel.add(txt);
JButton btn = new JButton("Enter");
btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
String result = ApplicationState.getInstance().acceptEarnings();
if (result != null) {
JOptionPane.showMessageDialog(null, result, "Error Entering Earnings", JOptionPane.ERROR_MESSAGE);
}
else {
JOptionPane.showMessageDialog(null, "The session minutes and earnings were accepted.", "Success!", JOptionPane.INFORMATION_MESSAGE);
JTextField sessionMinutes = (JTextField)contentPanel.getComponent(1);
sessionMinutes.setText("");
JTextField earnings = (JTextField)contentPanel.getComponent(3);
earnings.setText("");
sessionMinutes.requestFocus();
}
}
});
contentPanel.add(btn);
JTextArea textArea = new JTextArea();
textAreaPanel.add(textArea);
btn = new JButton("Run Report");
btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
}
});
buttons.add(btn);
btn = new JButton("Quit");
btn.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
});
buttons.add(btn);
pane.add(contentPanel, BorderLayout.CENTER);
pane.add(textAreaPanel, BorderLayout.CENTER);
pane.add(buttons, BorderLayout.SOUTH);
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event dispatch thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
TutoringCalculator frame = new TutoringCalculator("Tutoring Calculator");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
//Set up the content pane.
frame.addComponentsToPane(frame.getContentPane());
//Display the window.
frame.setPreferredSize(new Dimension(600, 400));
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
/* Use an appropriate Look and Feel */
try {
//UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
} catch (UnsupportedLookAndFeelException | IllegalAccessException | InstantiationException | ClassNotFoundException ex) {
ex.printStackTrace();
}
/* Turn off metal's use of bold fonts */
UIManager.put("swing.boldMetal", Boolean.FALSE);
//Schedule a job for the event dispatchi thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
createAndShowGUI();
}
});
}
}
アプリケーション状態
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package tutoringcalculator;
import javax.swing.border.Border;
/**
*
* @author Owner
*/
final public class ApplicationState {
private static ApplicationState instance = new ApplicationState();
public static ApplicationState getInstance() {
return instance;
}
private ApplicationState() {
}
private Border defaultTextFieldBorder;
public Border getDefaultTextFieldBorder() {
return defaultTextFieldBorder;
}
public void setDefaultTextFieldBorder(Border b) {
defaultTextFieldBorder = b;
}
private double currentSessionMinutes;
private boolean isValidSessionMinutes;
public boolean setCurrentSessionMinutes(String text) {
isValidSessionMinutes = false;
try {
currentSessionMinutes = Double.parseDouble(text);
isValidSessionMinutes = true;
}
catch (NumberFormatException nfe) {
return false;
}
return true;
}
private double currentEarnings;
private boolean isValidCurrentEarnings;
public boolean setCurrentEarnings(String text) {
isValidCurrentEarnings = false;
try {
currentEarnings = Double.parseDouble(text);
isValidCurrentEarnings = true;
}
catch (NumberFormatException nfe) {
return false;
}
return true;
}
public String acceptEarnings() {
if (!(isValidSessionMinutes && isValidCurrentEarnings)) {
return "Please enter valid session minutes and current earnings.";
}
addEarnings(currentSessionMinutes, currentEarnings);
return null;
}
private double[][] earningsArray = new double[100][2];
private int newRowIndex = 0;
private void addEarnings(double sessionMinutes, double earnings) {
earningsArray[newRowIndex][0] = sessionMinutes;
earningsArray[newRowIndex][1] = earnings;
newRowIndex++;
}
}
DecimalFieldFocusListener
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package tutoringcalculator;
import java.awt.Color;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import javax.swing.BorderFactory;
import javax.swing.JTextField;
/**
*
* @author Owner
*/
public class DecimalFieldFocusListener implements FocusListener {
private IValidDecimalValue _callback;
public DecimalFieldFocusListener(IValidDecimalValue callback) {
_callback = callback;
}
public void focusGained(FocusEvent e) {
}
public void focusLost(FocusEvent e) {
JTextField txt = (JTextField)e.getSource();
if (!_callback.callback(txt.getText())) {
txt.setBorder(BorderFactory.createMatteBorder(2, 2, 2, 2, Color.red));
}
else {
txt.setBorder(ApplicationState.getInstance().getDefaultTextFieldBorder());
txt.setBackground(Color.white);
}
}
}
IValidDecimalValue
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package tutoringcalculator;
/**
*
* @author Owner
*/
public interface IValidDecimalValue {
boolean callback(String val);
}