Java 是什么原因引起的;Can';“找不到符号”;如何修复它?
我一直在试图弄明白这一点,我在不同的程序中运行过它,所以它肯定在代码中。可能也很简单。错误是 Password2.java:90:错误:找不到符号 if(pw.equals(密码)) ^ 符号:可变密码 位置:类密码2.EnterButtonHandler 1错误 代码如下:Java 是什么原因引起的;Can';“找不到符号”;如何修复它?,java,compiler-errors,Java,Compiler Errors,我一直在试图弄明白这一点,我在不同的程序中运行过它,所以它肯定在代码中。可能也很简单。错误是 Password2.java:90:错误:找不到符号 if(pw.equals(密码)) ^ 符号:可变密码 位置:类密码2.EnterButtonHandler 1错误 代码如下: // Password1.java import javax.swing.*; import java.awt.*; import java.awt.event.ActionEvent; import java.awt.
// 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
password
对于Password2
构造函数是本地的
它应该被传递,或者是一个实例变量。您的类没有
密码的定义。因此,将其传递给方法时出现的错误等于方法。它找不到变量password
,在您对其进行编码时,该变量仅存在于Password2
构造函数中。您需要将password
设置为类成员变量,或者将其传递给处理程序的构造函数,以便它们可以引用它。阅读错误消息,热爱错误消息
这需要一些练习,但过一段时间后很容易看得更清楚:只需将下面的粗体文本作为一个句子阅读:)
错误:找不到符号[…]
符号:变量密码
位置:[in]类密码2.输入按钮句柄
在该范围/上下文中没有名为password
的内容(EnterButtonHandler
)
快乐编码
提示:在不同的作用域/上下文中存在同名的局部变量。。。也许它不应该是一个局部变量?有关详细信息,请参阅:)
是在Password2的构造函数中声明的局部变量。它不在EnterButtonHandler.actionPerformed方法的范围内。将其作为要解析的实例变量。@RobW正在尝试确定这是否是讽刺-->
password