我一直试图解决这个问题,我已经在不同的程序中运行它,所以它肯定在代码中。可能也很简单。错误说
Password2.java:90:错误:找不到符号 如果(pw.equals(密码)) ^ 符号:可变密码 location:class Password2.EnterButtonHandler 1错误
以下是代码:
// Password1.java
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Password2 extends JFrame // inherits from the JFrame class
{
// static final variables to hold frame dimensions (in pixels)
private static final int WIDTH = 400;
private static final int HEIGHT = 120;
//declare labels, fields, buttons, etc.
private JLabel enterLabel, validLabel, resultLabel;
private JTextField pwTextField;
private JButton enterB, clearB;
private EnterButtonHandler ebHandler;
private ClearButtonHandler cbHandler;
public Password2() // constructor defines frame
{
setTitle( "Password Checker" ); // set the title of the frame
setSize( WIDTH, HEIGHT ); // set the frame size
// prepare the container
Container pane = getContentPane();
GridLayout aGrid = new GridLayout( 3, 2, 5, 5 ); // create a 3 row 2 column layout
pane.setLayout( aGrid ); // set the layout for the frame
String password = "hello";
//instantiate JLabels
enterLabel = new JLabel("Enter Password: ");
validLabel = new JLabel("Validation: ");
resultLabel = new JLabel("");
//instantiate text fields
pwTextField = new JPasswordField( 30 );
//instantiate buttons
enterB = new JButton("Enter");
clearB = new JButton("Clear");
//initialize button handler
ebHandler = new EnterButtonHandler();
enterB.addActionListener(ebHandler);
//initialize button handler
cbHandler = new ClearButtonHandler();
clearB.addActionListener(cbHandler);
pane.add(enterLabel);
pane.add(pwTextField);
pane.add(validLabel);
pane.add(resultLabel);
pane.add(enterB);
pane.add(clearB);
//calls center frame method
centerFrame( WIDTH, HEIGHT );
}// end constructor
//methood to center GUI on screen
public void centerFrame( int frameWidth, int frameHeight)
{
//create toolkit object
Toolkit aToolkit = Toolkit.getDefaultToolkit();
//create a dimension object with user screen information
Dimension screen = aToolkit.getScreenSize();
//assign x, y position of upper left corner of frame
int xUpperLeft = ( screen.width - frameWidth ) / 2;
int yUpperLeft = ( screen.height - frameHeight ) / 2;
//method to position frame on user's screen
setBounds( xUpperLeft, yUpperLeft, frameWidth, frameHeight );
}
private class EnterButtonHandler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
String pw = pwTextField.getText();
if(pw.equals(password))
{
resultLabel.setText("Password Accepted");
pwTextField.setText("");
}
else
{
resultLabel.setText("Password Rejected");
pwTextField.setText("");
}
}
}
private class ClearButtonHandler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
resultLabel.setText("");
pwTextField.setText("");
}
}
public static void main(String [] args)
{
JFrame aPassword2 = new Password2(); // create the JFrame object
aPassword2.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
aPassword2.setVisible(true);
}
} // end of class
答案 0 :(得分:11)
阅读错误消息,喜欢错误消息。
这需要一些练习,但过了一段时间后很容易看清楚:只需阅读下面的粗体文字作为句子:)
错误:无法找到符号 [...]
符号:变量密码
位置: [in] 类Password2。 EnterButtonHandler
该范围/上下文中没有任何名为password
的内容(EnterButtonHandler
)。
快乐的编码。
提示:在不同的范围/上下文中有一个 local 变量具有相同的名称...也许它不应该是 local 变量?有关详情,请参阅The Java Tutorial: Variables。)
答案 1 :(得分:0)
password
是Password2
构造函数的本地。
它应该被传递,或者是一个实例变量。
答案 2 :(得分:0)
您的班级没有password
的定义。因此,将其传递给equals
方法时会出错。
答案 3 :(得分:0)
它找不到变量password
,正如您编码的那样,它只存在于Password2
构造函数中。您需要将password
作为类成员变量或将其传递给Handler
类的构造函数,以便它们可以引用它。
答案 4 :(得分:0)
password
是在Password2的构造函数中声明的局部变量。它不在EnterButtonHandler.actionPerformed method
范围内。使其成为要解析的实例变量。