[英]How to use a boolean outside the scope of a key listener
我創建了一個購物車登錄 JFrame 並添加了一個“shopkeeperToggle”,這樣當按下它時,用戶登錄到店主的 JFrame,否則登錄到購物者的 Z3AD02CFB81F6B63ADZBE478 問題是我不知道如何實現它,我嘗試將 boolean 設置為 false 每當在“shopkeeperToggle”鍵監聽器中釋放鍵時,顯然我無法使用按下的值 inside登錄按鈕。
這是切換的代碼:
shopkeeperToggle = new JToggleButton("Shopkeeper");
shopkeeperToggle.addKeyListener(new KeyAdapter() {
@Override
public void keyReleased(KeyEvent e) {
pressed = false;
}
});
這就是我在登錄按鈕中嘗試做的事情:
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);
}
}
}
這可能會為解決您的問題提供一些幫助。 這是一個完全可編譯的演示。 進行了以下更改。
Actions
代替KeyListener
。 設置涉及更多一點,但可以將它們配置為僅監視某些鍵。JButton
代替JToggleButton
。 沒有具體原因,可以更改。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);
}
}
}
}
Java 教程中介紹了Inner
(或nested
)類和action
圖
您可以將按下定義為 static 值;
class c {
static boolean pressed = true;
...
}
您可以在任何地方訪問;
c.pressed; //will return true if you don't change
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