Reputation: 438

What causes "Can't find Symbol" and how to fix it?

I've been trying to figure this out, I've run it in different programs so it's definitely in the code. Probably something easy too. The error says

Password2.java:90: error: cannot find symbol if(pw.equals(password)) ^ symbol: variable password location: class Password2.EnterButtonHandler 1 error

Here is the code:

// 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

Upvotes: 6

Answers (5)

user166390

Reputation:

Read the error message, love the error message.

It takes some practice, but after awhile it's easy to see it more clearly: just read across the bold text below as a sentence :)

error: cannot find symbol [...]

symbol: variable password

location: [in] class Password2.EnterButtonHandler

There is nothing named password in that scope/context (EnterButtonHandler).

Happy coding.

Hint: there is a local variable with the same name in a different scope/context... perhaps it shouldn't be a local variable? See The Java Tutorial: Variables for more :)

Upvotes: 11

Chris

Reputation: 23171

password

is a local variable declared in the constructor of Password2. It is not in scope in your EnterButtonHandler.actionPerformed method. Make it an instance variable to resolve.

Upvotes: 0

Nate W.

Reputation: 9249

It can't find the variable password, which, as you've coded it, only exists in the Password2 constructor. You'll need to either make password a class member variable or pass it to the constructor of your Handler classes, so they can have a reference to it.

Upvotes: 0