在卡布局内定位组件
我有一个主框架，我想用卡片布局在中心位置显示我的NewUser类的对象。这是我的主要课程
import java.awt.*; import java.awt.event.*; import javax.swing.*; public class CardLayoutDemo implements ItemListener { JPanel cards; //a panel that uses CardLayout final static String BUTTONPANEL = "Card with JButtons"; final static String TEXTPANEL = "Card with JTextField"; public void addComponentToPane(Container pane) { //Put the JComboBox in a JPanel to get a nicer look. JPanel comboBoxPane = new JPanel(); //use FlowLayout String comboBoxItems[] = { BUTTONPANEL, TEXTPANEL }; JComboBox cb = new JComboBox(comboBoxItems); cb.setEditable(false); cb.addItemListener(this); comboBoxPane.add(cb); //Create the "cards". NewUser newUser = new NewUser(); JPanel card1 = new JPanel(); card1.add(new JButton("Button 1")); card1.add(new JButton("Button 2")); card1.add(new JButton("Button 3")); JPanel card2 = new NewUser(); //Create the panel that contains the "cards". cards = new JPanel(new CardLayout()); cards.add(card1, BUTTONPANEL); cards.add(card2, TEXTPANEL); pane.add(comboBoxPane, BorderLayout.PAGE_START); pane.add(cards, BorderLayout.CENTER); } public void itemStateChanged(ItemEvent evt) { CardLayout cl = (CardLayout)(cards.getLayout()); cl.show(cards, (String)evt.getItem()); } /** * 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. JFrame frame = new JFrame("CardLayoutDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Create and set up the content pane. CardLayoutDemo demo = new CardLayoutDemo(); demo.addComponentToPane(frame.getContentPane()); //Display the window. 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 ex) { ex.printStackTrace(); } catch (IllegalAccessException ex) { ex.printStackTrace(); } catch (InstantiationException ex) { ex.printStackTrace(); } catch (ClassNotFoundException ex) { ex.printStackTrace(); } /* Turn off metal's use of bold fonts */ UIManager.put("swing.boldMetal", Boolean.FALSE); //Schedule a job for the event dispatch thread: //creating and showing this application's GUI. javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); } } 这是我的NewUser类
import java.awt.Dimension; import java.awt.Toolkit; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.KeyAdapter; import java.awt.event.KeyEvent; import javax.swing.JButton; import javax.swing.JLabel; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.JPasswordField; import javax.swing.JTextField; public class NewUser extends JPanel { private static final long serialVersionUID = 1L; private JLabel lblUsername, lblPassword, lblConfirmMsg; private JPasswordField txtPassword, txtCPassword; private JTextField txtUsername, txtName; private JButton btnSave, btnCancel; JPanel panelNewUser; Dimension screen = Toolkit.getDefaultToolkit().getScreenSize(); public NewUser() { this.setSize(350, 270); this.setLocation((screen.width - 500) / 2, ((screen.height - 350) / 2)); this.setLayout(null); panelNewUser= this; lblUsername = new JLabel("Username"); lblPassword = new JLabel("Password"); lblConfirmMsg = new JLabel("Re-enter Password"); txtName = new JTextField(); txtUsername = new JTextField(); txtPassword = new JPasswordField(); txtCPassword = new JPasswordField(); btnSave = new JButton("Save"); btnCancel = new JButton("Cancel"); lblUsername.setBounds(30, 30, 100, 25); this.add(lblUsername); txtUsername.setBounds(150, 30, 150, 25); this.add(txtUsername); lblPassword.setBounds(30, 70, 100, 25); this.add(lblPassword); txtPassword.setBounds(150, 70, 150, 25); this.add(txtPassword); lblConfirmMsg.setBounds(30, 110, 110, 25); this.add(lblConfirmMsg); txtCPassword.setBounds(150, 110, 150, 25); this.add(txtCPassword); btnSave.setBounds(60, 155, 100, 25); this.add(btnSave); btnCancel.setBounds(180, 155, 100, 25); this.add(btnCancel); txtName.addKeyListener(new KeyAdapter() { public void keyTyped(KeyEvent e) { char c = e.getKeyChar(); if (!(Character.isLetter(c) || (c == KeyEvent.VK_BACK_SPACE) || (c == KeyEvent.VK_SPACE) || (c == KeyEvent.VK_DELETE))) { getToolkit().beep(); JOptionPane.showMessageDialog(null, "Invalid Character", "ERROR", JOptionPane.ERROR_MESSAGE); e.consume(); } } }); txtUsername.addKeyListener(new KeyAdapter() { public void keyTyped(KeyEvent e) { char c = e.getKeyChar(); if (!(Character.isLetter(c) || (c == KeyEvent.VK_BACK_SPACE) || (Character.isDigit(c)) || (c == KeyEvent.VK_DELETE))) { getToolkit().beep(); JOptionPane.showMessageDialog(null, "Invalid Character", "ERROR", JOptionPane.ERROR_MESSAGE); e.consume(); } } }); btnCancel.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(ActionEvent e) { resetField(); panelNewUser.setVisible(false); System.out.println("hello"); } }); btnSave.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(ActionEvent e) { //DatabaseHelper databaseHelper = new DatabaseHelper(); if (txtUsername.getText() == null || txtUsername.getText().equals("")) { JOptionPane.showMessageDialog(null, "Enter Username", "Missing fields", JOptionPane.DEFAULT_OPTION); txtUsername.requestFocus(); return; } if (txtPassword.getPassword() == null || txtPassword.getPassword().equals("")) { JOptionPane.showMessageDialog(null, "Enter Password", "Missing fields", JOptionPane.DEFAULT_OPTION); txtPassword.requestFocus(); return; } if (txtCPassword.getPassword() == null || txtCPassword.getPassword().equals("")) { JOptionPane.showMessageDialog(null, "Confirm your password", "Missing fields", JOptionPane.DEFAULT_OPTION); txtCPassword.requestFocus(); return; } if (!txtPassword.getText() .equals(txtPassword.getText())) { JOptionPane.showMessageDialog(null, "Passwords do not match.", "ERROR", JOptionPane.DEFAULT_OPTION); txtCPassword.requestFocus(); return; } if (true) { JOptionPane.showMessageDialog(null, "A new user is created", "SUCCESS", JOptionPane.DEFAULT_OPTION); resetField(); } } }); }// constructor closed //action listener public void resetField() { txtUsername.setText(""); txtCPassword.setText(""); txtPassword.setText(""); } }// class closed
我希望NewUser的对象显示在主类的中心位置
欢迎来到图形用户界面设计的创意世界，在这里，你开发出令人敬畏的用户界面的字体大小，屏幕分辨率和DPI，将永远不会与最终用户相匹配……
现在，您有两个选择。 花费你的余生试图遇到每一个奇怪的边缘情况，在重新发明轮子的过程中，一个轮子已经以布局管理员的幌子为你提供（对不起，如果声音虚构，但大多数通过了解布局管理人员可以解决人们在Swing中遇到的问题：P）。
您可能希望阅读使用布局管理器和布局管理器 的可视指南
public class TestLayout02 { public static void main(String[] args) { new TestLayout02(); } public TestLayout02() { javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { /* 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 ex) { ex.printStackTrace(); } catch (IllegalAccessException ex) { ex.printStackTrace(); } catch (InstantiationException ex) { ex.printStackTrace(); } catch (ClassNotFoundException ex) { ex.printStackTrace(); } /* Turn off metal's use of bold fonts */ UIManager.put("swing.boldMetal", Boolean.FALSE); //Schedule a job for the event dispatch thread: //creating and showing this application's GUI. createAndShowGUI(); } }); } public class CardLayoutDemo implements ItemListener { JPanel cards; //a panel that uses CardLayout final static String BUTTONPANEL = "Card with JButtons"; final static String TEXTPANEL = "Card with JTextField"; public void addComponentToPane(Container pane) { //Put the JComboBox in a JPanel to get a nicer look. JPanel comboBoxPane = new JPanel(); //use FlowLayout String comboBoxItems[] = {BUTTONPANEL, TEXTPANEL}; JComboBox cb = new JComboBox(comboBoxItems); cb.setEditable(false); cb.addItemListener(this); comboBoxPane.add(cb); //Create the "cards". NewUser newUser = new NewUser(); JPanel card1 = new JPanel(); card1.add(new JButton("Button 1")); card1.add(new JButton("Button 2")); card1.add(new JButton("Button 3")); JPanel card2 = new NewUser(); //Create the panel that contains the "cards". cards = new JPanel(new CardLayout()); cards.add(card1, BUTTONPANEL); cards.add(card2, TEXTPANEL); pane.add(comboBoxPane, BorderLayout.PAGE_START); pane.add(cards, BorderLayout.CENTER); } public void itemStateChanged(ItemEvent evt) { CardLayout cl = (CardLayout) (cards.getLayout()); cl.show(cards, (String) evt.getItem()); } } /** * Create the GUI and show it. For thread safety, this method should be * invoked from the event dispatch thread. */ protected void createAndShowGUI() { //Create and set up the window. JFrame frame = new JFrame("CardLayoutDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Create and set up the content pane. CardLayoutDemo demo = new CardLayoutDemo(); demo.addComponentToPane(frame.getContentPane()); //Display the window. frame.pack(); frame.setVisible(true); } public class NewUser extends JPanel { private static final long serialVersionUID = 1L; private JLabel lblUsername, lblPassword, lblConfirmMsg; private JPasswordField txtPassword, txtCPassword; private JTextField txtUsername, txtName; private JButton btnSave, btnCancel; JPanel panelNewUser; Dimension screen = Toolkit.getDefaultToolkit().getScreenSize(); public NewUser() { // this.setSize(350, 270); // this.setLocation((screen.width - 500) / 2, ((screen.height - 350) / 2)); // this.setLayout(null); setLayout(new GridBagLayout()); panelNewUser = this; lblUsername = new JLabel("Username"); lblPassword = new JLabel("Password"); lblConfirmMsg = new JLabel("Re-enter Password"); txtName = new JTextField(); txtUsername = new JTextField(12); txtPassword = new JPasswordField(12); txtCPassword = new JPasswordField(12); btnSave = new JButton("Save"); btnCancel = new JButton("Cancel"); GridBagConstraints gbc = new GridBagConstraints(); gbc.gridx = 0; gbc.gridy = 0; gbc.insets = new Insets(2, 2, 2, 2); gbc.anchor = GridBagConstraints.WEST; // lblUsername.setBounds(30, 30, 100, 25); this.add(lblUsername, gbc); // txtUsername.setBounds(150, 30, 150, 25); gbc.gridx++; this.add(txtUsername, gbc); // lblPassword.setBounds(30, 70, 100, 25); gbc.gridx = 0; gbc.gridy++; this.add(lblPassword, gbc); // txtPassword.setBounds(150, 70, 150, 25); gbc.gridx++; this.add(txtPassword, gbc); // lblConfirmMsg.setBounds(30, 110, 110, 25); gbc.gridx = 0; gbc.gridy++; this.add(lblConfirmMsg, gbc); // txtCPassword.setBounds(150, 110, 150, 25); gbc.gridx++; this.add(txtCPassword, gbc); // btnSave.setBounds(60, 155, 100, 25); gbc.gridx = 0; gbc.gridy++; gbc.anchor = GridBagConstraints.CENTER; this.add(btnSave, gbc); // btnCancel.setBounds(180, 155, 100, 25); gbc.gridx++; this.add(btnCancel, gbc); // This is a bad idea, use a DocumentFilter txtName.addKeyListener(new KeyAdapter() { public void keyTyped(KeyEvent e) { char c = e.getKeyChar(); if (!(Character.isLetter(c) || (c == KeyEvent.VK_BACK_SPACE) || (c == KeyEvent.VK_SPACE) || (c == KeyEvent.VK_DELETE))) { getToolkit().beep(); JOptionPane.showMessageDialog(null, "Invalid Character", "ERROR", JOptionPane.ERROR_MESSAGE); e.consume(); } } }); // This is a bad idea, use a DocumentFilter txtUsername.addKeyListener(new KeyAdapter() { public void keyTyped(KeyEvent e) { char c = e.getKeyChar(); if (!(Character.isLetter(c) || (c == KeyEvent.VK_BACK_SPACE) || (Character.isDigit(c)) || (c == KeyEvent.VK_DELETE))) { getToolkit().beep(); JOptionPane.showMessageDialog(null, "Invalid Character", "ERROR", JOptionPane.ERROR_MESSAGE); e.consume(); } } }); btnCancel.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(ActionEvent e) { resetField(); panelNewUser.setVisible(false); System.out.println("hello"); } }); btnSave.addActionListener(new java.awt.event.ActionListener() { public void actionPerformed(ActionEvent e) { //DatabaseHelper databaseHelper = new DatabaseHelper(); if (txtUsername.getText() == null || txtUsername.getText().equals("")) { JOptionPane.showMessageDialog(null, "Enter Username", "Missing fields", JOptionPane.DEFAULT_OPTION); txtUsername.requestFocus(); return; } if (txtPassword.getPassword() == null || txtPassword.getPassword().equals("")) { JOptionPane.showMessageDialog(null, "Enter Password", "Missing fields", JOptionPane.DEFAULT_OPTION); txtPassword.requestFocus(); return; } if (txtCPassword.getPassword() == null || txtCPassword.getPassword().equals("")) { JOptionPane.showMessageDialog(null, "Confirm your password", "Missing fields", JOptionPane.DEFAULT_OPTION); txtCPassword.requestFocus(); return; } if (!txtPassword.getText() .equals(txtPassword.getText())) { JOptionPane.showMessageDialog(null, "Passwords do not match.", "ERROR", JOptionPane.DEFAULT_OPTION); txtCPassword.requestFocus(); return; } if (true) { JOptionPane.showMessageDialog(null, "A new user is created", "SUCCESS", JOptionPane.DEFAULT_OPTION); resetField(); } } }); }// constructor closed //action listener public void resetField() { txtUsername.setText(""); txtCPassword.setText(""); txtPassword.setText(""); } }// class closed }
您可能还希望阅读DocumentFilter 。
如果您希望手动执行此操作，则需要附加ComponentListener并监视componentResized事件并再次重新布局所有组件。
您还需要查看FontMetrics，以便您可以正确地考虑系统之间字体大小的差异……