当我编译这行时,74出现是一个非法的表达开始,为什么会这样?我完全无法弄清楚这一点,任何帮助都将非常感谢谢谢.
import java.awt.*; import javax.swing.*; public class NumericKeypadPanel2 extends JPanel { public NumericKeypadPanel2() { String num = " "; JPanel panel_main = new JPanel(); panel_main.setLayout(new BorderLayout()); JPanel keypad = new JPanel(); keypad.setLayout(new GridLayout (4, 3)); keypad.setBorder (BorderFactory.createLineBorder (Color.black, 3)); JButton b1 = new JButton ("1"); JButton b2 = new JButton ("2"); JButton b3 = new JButton ("3"); JButton b4 = new JButton ("4"); JButton b5 = new JButton ("5"); JButton b6 = new JButton ("6"); JButton b7 = new JButton ("7"); JButton b8 = new JButton ("8"); JButton b9 = new JButton ("9"); JButton b10 = new JButton ("*"); JButton b11 = new JButton ("0"); JButton b12 = new JButton ("#"); NumListener listener = new NumListener(); b1.addActionListener (listener); keypad.add (b1); keypad.add (b2); keypad.add (b3); keypad.add (b4); keypad.add (b5); keypad.add (b6); keypad.add (b7); keypad.add (b8); keypad.add (b9); keypad.add (b10); keypad.add (b11); keypad.add (b12); panel_main.add(keypad, BorderLayout.CENTER); JButton clear = new JButton ("Clear"); JLabel display = new JLabel(num); panel_main.add(clear, BorderLayout.SOUTH); panel_main.add(display, BorderLayout.NORTH); display.setBorder (BorderFactory.createLineBorder (Color.black, 3)); add(panel_main); private class NumListener implements ActionListener { public void actionPerformed (ActionEvent event) { Object source = event.getSource(); switch (source) { case b1: display.setText(display.getText()+"1"); break; case b2: display.setText(display.getText()+"2"); break; case b3: display.setText(display.getText()+"3"); break; case b4: display.setText(display.getText()+"4"); break; case b5: display.setText(display.getText()+"5"); break; case b6: display.setText(display.getText()+"6"); break; case b7: display.setText(display.getText()+"7"); break; case b8: display.setText(display.getText()+"8"); break; case b9: display.setText(display.getText()+"9"); break; case b10: display.setText(display.getText()+"*"); break; case b11: display.setText(display.getText()+"0"); break; case b12: display.setText(display.getText()+"#"); break; } } } } }
小智.. 5
只是一个疯狂的猜测:
Object source = event.getSource(); switch (source){ <-- ERROR
据我所知,switch语句不适用于对象.
只是一个疯狂的猜测:
Object source = event.getSource(); switch (source){ <-- ERROR
据我所知,switch语句不适用于对象.