我只是想弄清楚为什么会出现这些错误。我不确定为什么为什么说找不到变量，或者为什么不允许我加减一个int。
错误如下：
javac Dial2.java
Dial2.java:53: cannot find symbol
symbol : class arrl
location: class DialFrame
b.addActionListener(new arrl());
^
Dial2.java:56: b is already defined in DialFrame(java.lang.String)
Button b = new Button("<");
^
Dial2.java:57: cannot find symbol
symbol : class arrl
location: class DialFrame
b.addActionListener(new arrl());
^
Dial2.java:127: cannot find symbol
symbol : variable pastNumbeCount
location: class DialFrame.ArrowListener
arrowIndex = (arrowIndex + pastNumbeCount - 1) % pastNumberCount;
^
Dial2.java:127: operator + cannot be applied to int,pastNumbeCount
arrowIndex = (arrowIndex + pastNumbeCount - 1) % pastNumberCount;
^
Dial2.java:127: operator - cannot be applied to <nulltype>,int
arrowIndex = (arrowIndex + pastNumbeCount - 1) % pastNumberCount;
^
Dial2.java:128: cannot find symbol
symbol : variable arrowindex
location: class DialFrame.ArrowListener
phoneNumber.setText(pastNumbers[arrowindex - 1]);
^
Dial2.java:133: cannot find symbol
symbol : variable pastNumberindex
location: class DialFrame.ArrowListener
phoneNumber.setText(pastNumberindex);
^
8 errors
这是一个简单的电话拨号程序的代码：
cat Dial2.java
import java.awt.*;
import java.awt.event.*;
// Driver class
public class Dial2 {
public static void main(String[] args) {
Frame frame = new DialFrame("Dial");
frame.pack();
frame.setVisible(true);
}
}
// Frame class
class DialFrame extends Frame {
private TextField phoneNumber = new TextField();
private String pastNumbers[] = new String[10];
private int pastNumberCount = 0;
private int pastNumberIndex = 0;
private int arrowIndex = 0;
// Constructor
public DialFrame(String title) {
// Set title
super(title);
// set all pastNumbers to empty string
for (int x = 0; x < pastNumbers.length; x++)
pastNumbers[x] = "";
// Make text field non-editable and put at top of frame
phoneNumber.setEditable(false);
add("North", phoneNumber);
// Create panel to hold buttons and set its layout
Panel buttonPanel = new Panel();
buttonPanel.setLayout(new GridLayout(4, 3, 10, 10));
DigitListener dl = new DigitListener();
ArrowListener arrl = new ArrowListener();
// Create first nine buttons, attach a listener to each,
// and add buttons to buttonPanel
for (int i = 1; i <= 9; i++) {
Button b = new Button(i + "");
b.addActionListener(dl);
buttonPanel.add(b);
}
// **1** Add your two new buttons to your panel, along with an
// an arrow listener for both
Button b = new Button(">");
b.addActionListener(new arrl());
b = new Button("0");
Button b = new Button("<");
b.addActionListener(new arrl());
buttonPanel.add(b);
// Create a panel to hold buttonPanel; put it at the
// center of the frame
Panel centerPanel = new Panel();
centerPanel.add(buttonPanel);
add("Center", centerPanel);
// Create a panel to hold the "Dial" button; put it at
// the bottom of the frame
Panel bottomPanel = new Panel();
b = new Button("Dial");
b.addActionListener(new DialListener());
bottomPanel.add(b);
add("South", bottomPanel);
// Attach window listener
addWindowListener(new WindowCloser());
}
private void addPastNumber(String num) {
boolean numberAlreadyAdded = false;
for (int x=0; x < pastNumbers.length; x++) {
if (pastNumbers[x].equals(num)) {
numberAlreadyAdded = true; break;
}
}
if (!numberAlreadyAdded) {
pastNumbers[pastNumberIndex] = num;
pastNumberIndex++;
if (pastNumberCount < 10) pastNumberCount++;
if (pastNumberIndex == pastNumbers.length) pastNumberIndex = 0;
}
arrowIndex = pastNumberIndex;
}
// Listener for all buttons
class DigitListener implements ActionListener {
public void actionPerformed(ActionEvent evt) {
String buttonLabel = evt.getActionCommand();
// append the digit on the newly pressed key
phoneNumber.setText(phoneNumber.getText() + buttonLabel);
}
}
// Listener for all buttons
class DialListener implements ActionListener {
public void actionPerformed(ActionEvent evt) {
addPastNumber(phoneNumber.getText());
phoneNumber.setText("Dialing...");
// pause for two seconds, or 2000 millisecond
try {
Thread.sleep(2000);
} catch (InterruptedException e) {}
phoneNumber.setText("");
}
}
// Listener for "arrow" buttons
class ArrowListener implements ActionListener {
public void actionPerformed(ActionEvent evt) {
// ** 2 **
String buttonLabel = evt.getActionCommand();
if (buttonLabel == "<")
{
arrowIndex = (arrowIndex + pastNumbeCount - 1) % pastNumberCount;
phoneNumber.setText(pastNumbers[arrowindex - 1]);
}
else
{
arrowIndex = (arrowIndex + 1) % pastNumberCount;
phoneNumber.setText(pastNumberindex);
}
}
}
// Listener for window
class WindowCloser extends WindowAdapter {
public void windowClosing(WindowEvent evt) {
System.exit(0);
}
}
}
任何帮助或信息将不胜感激。
说明：如果pastNumberNumbers数组中的当前索引为9，则按“>”键将显示存储在索引0中的数字。如果当前索引为0，则按“
要进行此设置，我需要从按钮中检索标签。如果它是“ （arrowIndex + pastNumberCount-1）％pastNumberCount;
并将过去号码数组中此索引处的过去号码添加到phoneNumber文本字段中。
否则，我需要将数组索引设置为：（arrowIndex + 1）％pastNumberCount，并将该索引处的过去数字添加到您的文本字段中。
最佳答案
使用new ArrowListener（）代替new arrl（）; （arrl不是一个类，它是一个对象）
使用pastNumberCount而不是pastNumbeCount（r缺失）
使用arrowIndex代替arrowindex（我应该是大写字母）
使用pastNumberIndex代替pastNumberindex（我应该为大写字母）
您的程序中有很多错别字。
问候，
亚什