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java - 如何在关键侦听器范围之外使用布尔值

问题描述

我创建了一个购物车登录 JFrame，并添加了一个“shopkeeperToggle”，以便在按下它时用户登录到店主的 JFrame，否则登录到购物者的 jframe。问题是我不知道如何实现它，每当在“shopkeeperToggle”键侦听器中释放键时，我都尝试将布尔值“pressed”设置为 false，显然我无法使用内部按下的值登录按钮。

这是切换的代码：

    shopkeeperToggle = new JToggleButton("Shopkeeper");
    shopkeeperToggle.addKeyListener(new KeyAdapter() {
        @Override
        public void keyReleased(KeyEvent e) {
            pressed = false;
        }
    });

这就是我在登录按钮中尝试做的事情：

signinButton = new JButton("Sign in ");
    signinButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
             try {
                        Class.forName("com.mysql.jdbc.Driver");
                        Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3308/shoppingCart","root","");
                        // select the users that have the inputted credentials from the database
                        String sql = "SELECT * FROM users WHERE userUsername = ? AND userEmail =?AND userPassword = ? ";
                    PreparedStatement ps = conn.prepareStatement(sql);
                    ps.setString(1,usernamelogin.getText());
                    ps.setString(2, emaillogin.getText());
                    ps.setString(3,passwordlogin.getText());
                    ResultSet rs = ps.executeQuery();
                    // if query executed and 
                    if (rs.next()) {
                        // if login succ show window log succ, and go to home shopping page
                            JOptionPane.showMessageDialog(null,"Login successful! :)");
/////////////////this is where I fail////////////////////
                            if (pressed) {
                                OwnerHomePage ownerhome = new OwnerHomePage();
                                ownerhome.setVisible(true);
                                setVisible(false);
                            } else {
                                UserHomePage home = new UserHomePage();
                                home.setVisible(true);
                                setVisible(false);
                            }
                        } else {
                            JOptionPane.showMessageDialog(null,"Wrong Username or Email or Password :(");
                        }
                    } catch (Exception e1) {
                        JOptionPane.showMessageDialog(null,e1);
                    }
                }
            }

标签： javaswingjframeawtkeylistener

解决方案

这可能会为解决您的问题提供一些帮助。这是一个完全可编译的演示。进行了以下更改。

  • 代替. Actions_ KeyListener设置涉及更多一点，但可以将它们配置为仅监视某些键。
  • 用 aJButton代替 a JToggleButton。没有具体原因，可以更改。
  • 为侦听器创建单独的内部类。倾向于减少混乱并且通常更具可读性。
  • 根据模式更改按钮的名称。
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.AbstractAction;
import javax.swing.InputMap;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.SwingUtilities;

public class ActionMapAndButtons {

    JFrame frame = new JFrame("Demo");

    public static void main(String[] args) {
        SwingUtilities
                .invokeLater(() -> new ActionMapAndButtons().start());
    }

    public void start() {
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        MyClass cls = new MyClass();
        frame.add(cls);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

class MyClass extends JPanel {
    JButton button = new JButton("Shopper Sign in");
    boolean pause = false;

    public MyClass() {
        setPreferredSize(new Dimension(300, 300));
        button.addActionListener(new ButtonListener());
        add(button);
        InputMap map = getInputMap(WHEN_ANCESTOR_OF_FOCUSED_COMPONENT);
        for (int i = 0; i < 256; i++) {
            map.put(KeyStroke.getKeyStroke((char)i), "anyKey");
        }
        getActionMap().put("anyKey", new MyAction());
        setFocusable(true);

    }

    private class ButtonListener implements ActionListener {
        public void actionPerformed(ActionEvent ae) {
            Object obj = ae.getSource();
            if (obj instanceof JButton) {
                JButton b = (JButton) obj;
                pause = !pause;
                if (pause) {
                    b.setText("Shopkeeper Sign in");
                } else {
                    b.setText("Shopper Sign in");
                }
            }
        }
    }

    private class MyAction extends AbstractAction {
        public void actionPerformed(ActionEvent ae) {
            String cmd = ae.getActionCommand();
            if (pause) {
                System.out.println("Shopkeeper - " + cmd);
            } else {
                System.out.println("Shopper - " + cmd);
            }
        }
    }
}

Inner（或nested）类和action映射包含在Java 教程中

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