如何不同的ActionListener添加到相同的对象 [英] How to add different actionlisteners to the same object
问题描述
我如何不同的ActionListeners添加到P1的对象。我希望程序能够在textbar设置为适当的数量时$ P $与相应的按钮pssed。因为它们不是不同的变量，我不能简单地用code以下（在我的actionPerformed功能），
如果（e.getSource（）==按钮1）{
txtField.setText（1）;
}
进口java.awt中的*。
导入的java.applet。*;
java.awt.event中导入*。公共类电话扩展小程序实现的ActionListener
{
文本字段txtField; 公共无效的init（）{
的setLayout（新的BorderLayout（））; txtField =新的TextField（）;
加（txtField，BorderLayout.NORTH）; 面板P1 =新面板（）;
p1.setLayout（新的GridLayout（4,3））;
p1.add（新按钮（1））;
p1.add（新按钮（2））;
p1.add（新按钮（3））;
p1.add（新按钮（4））;
p1.add（新按钮（5））;
p1.add（新按钮（6））;
p1.add（新按钮（7））;
p1.add（新按钮（8））;
p1.add（新按钮（9））;
p1.add（新按钮（*））;
p1.add（新键（0））;
p1.add（新按钮（＃））;
加（P1，BorderLayout.CENTER）; } 公共无效的actionPerformed（ActionEvent的五）{
}
}
没有你的GUI类也是监听器类作为的要求类的事太多了。相反，考虑使用匿名内部监听类或私有内部类。顺便说一句，我没有看到你添加任何听众的按钮。此外，对于我的钱，我想创建一个Swing GUI的，而不是一个AWT GUI的Swing是一个更强大和灵活的。
另外请注意，上面的例子中，我会在实际上给我所有的按钮对象相同的动作侦听器。如果使用摇摆，我可以简单地让这将是数息字符串ActionEvent对象的actionCommand。无需10 if块或交换机模块。
例如，这表明在显示一个JTextField的一些非常简单的逻辑，但没有计算逻辑：
进口java.awt.BorderLayout中;
进口java.awt.GridLayout中;
进口java.awt.event.ActionEvent中;进口的javax.swing *。公共类CalcEg {
私有静态最终浮动BTN_FONT_SIZE = 18F;
私有静态最后的String [] [] = BTN_LABELS {
{7，8，9， - }，
{4，5，6，+}，
{1，2，3，/}，
{0，。，=，*}
};
私人的JPanel的mainPanel =新JPanel（）;
私人JTextField的文本框=新的JTextField（10）; 公共CalcEg（）{
诠释行= BTN_LABELS.length;
INT COLS = BTN_LABELS [0]。长度;
INT间隙= 4; JPanel的buttonPanel =新JPanel（新网格布局（行，COLS，缺口，缺口））;
对于（字符串[] btnLabelRow：BTN_LABELS）{
对于（字符串btnLabel：btnLabelRow）{
JButton的BTN = createButton（btnLabel）;
如果（0123456789。含有（btnLabel））{
btn.setAction（新NumberListener（btnLabel））;
}
buttonPanel.add（BTN）;
}
} textField.setFont（textField.getFont（）的deriveFont（BTN_FONT_SIZE））; mainPanel.setLayout（新的BorderLayout（间隙，间隙））;
mainPanel.setBorder（BorderFactory.createEmptyBorder（缺口，缺口，缺口，缺口））;
mainPanel.add（文本框，BorderLayout.PAGE_START）;
mainPanel.add（buttonPanel，BorderLayout.CENTER）;
} 私人的JButton createButton（字符串btnLabel）{
JButton的按钮=的新的JButton（btnLabel）;
button.setFont（button.getFont（）的deriveFont（BTN_FONT_SIZE））;
返回按钮;
} 公共JComponent的getMainComponent（）{
返回mainPanel中;
} 私有类NumberListener扩展AbstractAction {
NumberListener（字符串actionCommand）{
超（actionCommand）;
} @覆盖
公共无效的actionPerformed（ActionEvent的五）{
串actionCommand = e.getActionCommand（）;
textField.setText（textField.getText（）+ actionCommand）;
}
} 私有静态无效createAndShowGui（）{
CalcEg的mainPanel =新CalcEg（）; JFrame的帧=新的JFrame（CalcEg）;
frame.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）;
。frame.getContentPane（）加（mainPanel.getMainComponent（））;
frame.pack（）;
frame.setLocationByPlatform（真）;
frame.setVisible（真）;
} 公共静态无效的主要（字串[] args）{
SwingUtilities.invokeLater（Runnable的新（）{
公共无效的run（）{
createAndShowGui（）;
}
}）;
}
}
How do I add different actionlisteners to the p1 objects. I want the program to be able to set the textbar to the appropriate number when pressed with the appropriate button. Since they are not different variables I cannot simply use the code below(in my actionPerformed function),
if (e.getSource() == button1){
txtField.setText("1");
}
import java.awt.*;
import java.applet.*;
import java.awt.event.*;
public class Telephone extends Applet implements ActionListener
{
TextField txtField;
public void init() {
setLayout(new BorderLayout());
txtField = new TextField("");
add(txtField, BorderLayout.NORTH);
Panel p1 = new Panel();
p1.setLayout(new GridLayout(4, 3));
p1.add(new Button("1"));
p1.add(new Button("2"));
p1.add(new Button("3"));
p1.add(new Button("4"));
p1.add(new Button("5"));
p1.add(new Button("6"));
p1.add(new Button("7"));
p1.add(new Button("8"));
p1.add(new Button("9"));
p1.add(new Button("*"));
p1.add(new Button("0"));
p1.add(new Button("#"));
add(p1, BorderLayout.CENTER);
}
public void actionPerformed(ActionEvent e) {
}
}
Don't have your GUI class also be your listener class as that's asking the class to do too much. Instead consider using anonymous inner listener classes or private inner classes. Incidentally, I don't see where you're adding any listeners to your buttons. Also, for my money, I'd create a Swing GUI, not an AWT GUI as Swing is much more robust and flexible.
Also note, for the example above, I would in fact give all my button objects the same action listener. If using Swing, I could simply get the ActionEvent object's actionCommand which would be the number String of interest. No need for 10 if blocks or a switch block.
For example, this demonstrates very simple logic of displaying the number in a JTextField, but has no calculation logic:
import java.awt.BorderLayout;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import javax.swing.*;
public class CalcEg {
private static final float BTN_FONT_SIZE = 18f;
private static final String[][] BTN_LABELS = {
{"7", "8", "9", "-"},
{"4", "5", "6", "+"},
{"1", "2", "3", "/"},
{"0", ".", "=", "*"}
};
private JPanel mainPanel = new JPanel();
private JTextField textField = new JTextField(10);
public CalcEg() {
int rows = BTN_LABELS.length;
int cols = BTN_LABELS[0].length;
int gap = 4;
JPanel buttonPanel = new JPanel(new GridLayout(rows, cols, gap, gap));
for (String[] btnLabelRow : BTN_LABELS) {
for (String btnLabel : btnLabelRow) {
JButton btn = createButton(btnLabel);
if ("0123456789.".contains(btnLabel)) {
btn.setAction(new NumberListener(btnLabel));
}
buttonPanel.add(btn);
}
}
textField.setFont(textField.getFont().deriveFont(BTN_FONT_SIZE));
mainPanel.setLayout(new BorderLayout(gap, gap));
mainPanel.setBorder(BorderFactory.createEmptyBorder(gap, gap, gap, gap));
mainPanel.add(textField, BorderLayout.PAGE_START);
mainPanel.add(buttonPanel, BorderLayout.CENTER);
}
private JButton createButton(String btnLabel) {
JButton button = new JButton(btnLabel);
button.setFont(button.getFont().deriveFont(BTN_FONT_SIZE));
return button;
}
public JComponent getMainComponent() {
return mainPanel;
}
private class NumberListener extends AbstractAction {
NumberListener(String actionCommand) {
super(actionCommand);
}
@Override
public void actionPerformed(ActionEvent e) {
String actionCommand = e.getActionCommand();
textField.setText(textField.getText() + actionCommand);
}
}
private static void createAndShowGui() {
CalcEg mainPanel = new CalcEg();
JFrame frame = new JFrame("CalcEg");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel.getMainComponent());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
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