问题

在以下的代码中，当我执行它时，只有第一个 if 块会起作用（当我按下其他选项的按钮时，没有弹出窗口）。我做错了什么？这是一个用于创建一个可以在二进制、十进制和十六进制之间转换数字的应用程序的程序。

public class Menu implements ActionListener {
    public static void main(String[] args) {
        new Menu().createMenu();
    }

    JFrame frame = new JFrame();
    JPanel panel = new JPanel();
    JButton binToHex = new JButton("Bin to Hex");
    JButton binToDec = new JButton("Bin to Dec");
    JButton hexToBin = new JButton("Hex to Bin");
    JButton hexToDec = new JButton("Hex to Dec");
    JButton decToHex = new JButton("Dec to Hex");
    JButton decToBin = new JButton("Dec to Bin");

    private void createMenu() {
        frame.setVisible(true);
        frame.add(panel);
        panel.add(binToHex);
        panel.add(binToDec);
        panel.add(hexToBin);
        panel.add(hexToDec);
        panel.add(decToHex);
        panel.add(decToBin);
        frame.pack();
        binToHex.addActionListener(this);
    }

    public void actionPerformed(ActionEvent e) {
        String input = new String();
        if (e.getSource() == binToHex) {
            input = JOptionPane.showInputDialog(null, "Enter a binary number");
            Binary.convertToHexadecimal();
        } 
        
        if (e.getSource() == binToDec) {
            input = JOptionPane.showInputDialog(null, "Enter a binary number");
            Binary.convertToDecimal();
        } 
        
        if (e.getSource() == hexToBin) {
            input = JOptionPane.showInputDialog(null, "Enter a hexadecimal number");
            Hexadecimal.convertToBinary();
        }
        
        if (e.getSource() == hexToDec) {
            input = JOptionPane.showInputDialog(null, "Enter a hexadecimal number");
            Hexadecimal.convertToDecimal();
        }
        
        if (e.getSource() == decToHex) {
            input = JOptionPane.showInputDialog(null, "Enter a decimal number");
            Decimal.convertToHexadecimal(input);
        }
        
        if (e.getSource() == decToBin) {
            input = JOptionPane.showInputDialog(null, "Enter a decimal number");
            Decimal.convertToBinary(input);
        }
        
    }
}

如果你遇到了只有第一个 if 块起作用的问题，这可能是因为其他选项的按钮没有绑定正确的动作监听器，或者在按钮被按下时没有执行相应的转换操作。请确保每个按钮都正确地绑定了 ActionListener，并在相应的 if 块中执行相应的转换操作。

public class Menu implements ActionListener {
public static void main(String[] args) {
new Menu().createMenu();
}
JFrame frame = new JFrame();
JPanel panel = new JPanel();
JButton binToHex = new JButton("Bin to Hex");
JButton binToDec = new JButton("Bin to Dec");
JButton hexToBin = new JButton("Hex to Bin");
JButton hexToDec = new JButton("Hex to Dec");
JButton decToHex = new JButton("Dec to Hex");
JButton decToBin = new JButton("Dec to Bin");
private void createMenu() {
frame.setVisible(true);
frame.add(panel);
panel.add(binToHex);
panel.add(binToDec);
panel.add(hexToBin);
panel.add(hexToDec);
panel.add(decToHex);
panel.add(decToBin);
frame.pack();
binToHex.addActionListener(this);
}
public void actionPerformed(ActionEvent e) {
String input = new String();
if (e.getSource() == binToHex) {
input = JOptionPane.showInputDialog(null, "Enter a binary number");
Binary.convertToHexadecimal();
} 
if (e.getSource() == binToDec) {
input = JOptionPane.showInputDialog(null, "Enter a binary number");
Binary.convertToDecimal();
} 
if (e.getSource() == hexToBin) {
input = JOptionPane.showInputDialog(null, "Enter a hexadecimal number");
Hexadecimal.convertToBinary();
}
if (e.getSource() == hexToDec) {
input = JOptionPane.showInputDialog(null, "Enter a hexadecimal number");
Hexadecimal.convertToDecimal();
}
if (e.getSource() == decToHex) {
input = JOptionPane.showInputDialog(null, "Enter a decimal number");
Decimal.convertToHexadecimal(input);
}
if (e.getSource() == decToBin) {
input = JOptionPane.showInputDialog(null, "Enter a decimal number");
Decimal.convertToBinary(input);
}
}

答案1

得分: 3

你忘记在所有的 JButton 实例上调用 addActionListener 方法：

binToHex.addActionListener(this); // 你已经有这个
binToDec.addActionListener(this);
hexToBin.addActionListener(this);
hexToDec.addActionListener(this);
decToHex.addActionListener(this);
decToBin.addActionListener(this);

binToHex.addActionListener(this); // you have this one
binToDec.addActionListener(this);
hexToBin.addActionListener(this);
hexToDec.addActionListener(this);
decToHex.addActionListener(this);
decToBin.addActionListener(this);