我的任务是创建一个显示数字键盘的程序（如手机上的键盘），并有一个显示所选数字的屏幕。还包括一个清除按钮，清除屏幕。
在创建程序时，我创建了三个类。 Phone类只是创建一个JFrame，将PhonePanel添加到屏幕上。 PhonePanel类添加了一个充当屏幕的JLabel，一个充当清除按钮的JButton，以及一个作为数字键的JButtons GridLayout的KeypadPanel。
清除按钮和数字按钮都使用单独的动作侦听器。这是解决这个问题最有效的方法吗？有没有办法可以使用一个动作监听器而不是两个？
// ******************************************************************************************
// Phone.java
// David Read
// This class creates a JFrame that contains a PhonePanel. The PhonePanel provides a
// user interface that allows one to input numeric symbols on a screen and allows clearing
// of the screen.
// ******************************************************************************************
package lab5;
import javax.swing.JFrame;
public class Phone {
public static void main(String[] args)
{
// Create a JFrame object.
JFrame frame = new JFrame ("Phone");
// Set the default close operation for the JFrame.
frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
// Add a Phone panel to the screen.
frame.getContentPane().add(new PhonePanel());
frame.pack();
frame.setVisible(true);
}
}
// ******************************************************************************************
// PhonePanel.java
// David Read
// This class creates a JPanel that includes an output label which displays inputed numeric
// symbols, a clear button that clears what is displayed on the output label, and a KeypadPanel
// which displays a GridLayout of buttons that when pressed, display their corresponding symbols
// on the output label.
// ******************************************************************************************
package lab5;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class PhonePanel extends JPanel
{
private static JLabel labelOutput;
private JButton buttonClear;
//-----------------------------------------------------------------------
// Creates a JPanel that arranges three objects in a Border layout. The
// north component contains a JLabel, the east component contains a JButton
// and the center component contains a KeypadPanel.
//-----------------------------------------------------------------------
public PhonePanel()
{
// Set the layout manager, size and background color of the Phone Panel.
setLayout(new BorderLayout());
setPreferredSize (new Dimension(400, 200));
setBackground (Color.yellow);
// Output label created.
labelOutput = new JLabel(" ");
// Clear button created, assigned a button title and assigned an action listener.
buttonClear = new JButton();
buttonClear.setText("Clear");
buttonClear.addActionListener(new ClearButtonListener());
// Add the JLabel, JButton and KeypadPanel to the PhonePanel.
add(labelOutput, BorderLayout.NORTH);
add(buttonClear, BorderLayout.EAST);
add(new KeypadPanel(), BorderLayout.CENTER);
}
//-----------------------------------------------------------------------
// Adds the specified symbol to the output label.
//-----------------------------------------------------------------------
public static void addToOutputLabel(String input)
{
// Create a String object to hold the current value of the output label.
String label = labelOutput.getText();
// Append the inputed String onto the String.
label += input;
// Update the output label with the appended String.
labelOutput.setText(label);
}
//-----------------------------------------------------------------------
// Listens for the clear button to be pressed. When pressed, the output
// label is reassigned as blank.
//-----------------------------------------------------------------------
private class ClearButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
labelOutput.setText(" ");
}
}
}
// ******************************************************************************************
// KeypadPanel.java
// David Read
// This class creates a JPanel that contains several buttons which when pressed, adds their
// corresponding numeric symbol to the output label in the PhonePanel.
// ******************************************************************************************
package lab5;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JPanel;
public class KeypadPanel extends JPanel
{
private JButton button1, button2, button3, button4, button5, button6, button7, button8, button9, buttonStar, button0, buttonNumber;
//-----------------------------------------------------------------------
// Creates a JPanel that arranges several JButtons in a GridLayout. Each
// of the buttons are assigned button titles, action listeners and
// action commands.
//-----------------------------------------------------------------------
public KeypadPanel()
{
// Set layout to a GridLayout with 4 rows and 3 columns.
setLayout(new GridLayout(4,3));
// Create new JButtons.
button1 = new JButton();
button2 = new JButton();
button3 = new JButton();
button4 = new JButton();
button5 = new JButton();
button6 = new JButton();
button7 = new JButton();
button8 = new JButton();
button9 = new JButton();
buttonStar = new JButton();
button0 = new JButton();
buttonNumber = new JButton();
// Assign button titles to the JButtons.
button1.setText("1");
button2.setText("2");
button3.setText("3");
button4.setText("4");
button5.setText("5");
button6.setText("6");
button7.setText("7");
button8.setText("8");
button9.setText("9");
buttonStar.setText("*");
button0.setText("0");
buttonNumber.setText("#");
// Create a new KeypadButtonListener.
KeypadButtonListener listener = new KeypadButtonListener();
// Assign the listener as an action listener for all of the JButton objects.
button1.addActionListener(listener);
button2.addActionListener(listener);
button3.addActionListener(listener);
button4.addActionListener(listener);
button5.addActionListener(listener);
button6.addActionListener(listener);
button7.addActionListener(listener);
button8.addActionListener(listener);
button9.addActionListener(listener);
buttonStar.addActionListener(listener);
button0.addActionListener(listener);
buttonNumber.addActionListener(listener);
// Set the action commands for all of the JButtons.
button1.setActionCommand("1");
button2.setActionCommand("2");
button3.setActionCommand("3");
button4.setActionCommand("4");
button5.setActionCommand("5");
button6.setActionCommand("6");
button7.setActionCommand("7");
button8.setActionCommand("8");
button9.setActionCommand("9");
buttonStar.setActionCommand("*");
button0.setActionCommand("0");
buttonNumber.setActionCommand("#");
// Add the JButtons to the KeypadPanel.
add(button1);
add(button2);
add(button3);
add(button4);
add(button5);
add(button6);
add(button7);
add(button8);
add(button9);
add(buttonStar);
add(button0);
add(buttonNumber);
}
//-----------------------------------------------------------------------
// Listens for all of the buttons to be pressed. When a particular button
// is pressed, the addToOutputLabel method of the PhonePanel is called
// with the input being the action command of the button pressed.
//-----------------------------------------------------------------------
private class KeypadButtonListener implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
// Add the action command string to the output label.
PhonePanel.addToOutputLabel(e.getActionCommand());
}
}
}
答案 0 :(得分：1)
在这种情况下，最好使用两个单独的动作侦听器作为清除按钮的功能，而数字按钮则不同。 在开发课程时，最佳做法是使用单一责任原则（https://en.wikipedia.org/wiki/Single_responsibility_principle）。这将使您的代码更易于维护，更易于阅读和修改。
答案 1 :(得分：1)
最好在这里使用多个ActionListener，但是，如果您仍然希望使用一个ActionListener，则可以创建一个单独的类来处理与此类似的所有操作。
sprintfc