New to Java, cannot find symbol error

Question

I'm new to Java and I keep getting errors on compile, notably the "cannot find symbol error." I'm trying to get the string in the table to go in as the file destination, but I can't call the table so I tried using the variable holder, only to get an error again.

Along with that I was trying to change what kinds of files can be opened on the filechooser, but I can't find a solution that will work.

And finally, could someone maybe explain what a missing symbol is? Because I feel like I'm misunderstanding it since I've tried to fix it a bunch of times with no success.

//C:\\Users\\Andrew\\Downloads\\never gonna give you up.wav
//Andrew Douglas
//Imports
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.sound.sampled.*;
import javax.swing.filechooser.*;
import javax.swing.JTable;

//Creates class
public class jPlayer extends JFrame implements ActionListener {

    //Sets up form items and necessary globals
    JButton save, play, stop, loop;
    JFileChooser dialog;

    String Artist, Song, Album, Loc;
    Object[][] data;
    int n = 1;
    String holder;
    //Makes the library, with a 51 song limit.
    jLibrary[] addedSong = new jLibrary[50];

    public jPlayer() {
        //Creates frame
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setTitle("jPlayer");
        this.setSize(800, 600);
        //Makes titles for table
        String[] columnNames =  {"Artist",
                                "Song",
                                "Album",
                                "Location"};
        //Gives one value for array
        addedSong[0] = new jLibrary("Rick Astley", "NGGYU", "UnKnown", "C:\\Users\\Andrew\\Downloads\\never gonna give you up.wav");
        //Adds it to table array
        Object[][] data = {
        {
            addedSong[0]
        }

        };
        //Creates table
        final Jtable table = new JTable(data, columnNames);
        table.setPreferredScrollableViewportSize(new Dimension(500, 70));
        table.setFillsViewportHeight(true);
        //Lets it sort the rows
        table.setAutoCreateRowSorter(true);
        //Creates the scroller
        JScrollPane scrollPane = new JScrollPane(table);
        //Makes the save file dialog and the play and save buttons
        dialog = new JFileChooser();
        play = new JButton ("Play Song");
        save = new JButton ("Save a file");
        //Adds the button listeners
        save.addActionListener(this);
        play.addActionListener(this);
        //Adds buttons to panel
        JPanel buttons = new JPanel();
        buttons.add(save);
        buttons.add(play);
        //Puts the buttons at the bottom
        add(buttons, BorderLayout.SOUTH);
        add(scrollPane);
        this.setVisible(true);
        holder = table.getselectedRows[3];

    }
    //Creates action listener for button
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == save) {
            dialog.setFileFilter(new FileNameExtensionFiler("Wave File (*.wav)"));
            int returnVal = dialog.showSaveDialog(jPlayer.this);
            if (returnVal == dialog.APPROVE_OPTION) {
                File file = dialog.getSelectedFile();
                addToLibrary("", "", "", file.getName());

            }
        }
        else if (e.getSource() == play) {
            try {
            File soundFile = new File(holder);
            System.out.println(soundFile);
            AudioInputStream audioIn = AudioSystem.getAudioInputStream(soundFile);
            Clip clip = AudioSystem.getClip();
            clip.open(audioIn);
            clip.start();
            } catch (UnsupportedAudioFileException f) {
         f.printStackTrace();
      } catch (IOException f) {
         f.printStackTrace();
      } catch (LineUnavailableException f) {
         f.printStackTrace();
      }

    } }
    public static void main(String[]args) {
        new jPlayer();
    }
    public void addToLibrary(String art, String song, String alb, String file) {
            addedSong[n] = new jLibrary(art, song, alb, file);
            int j = 0;
            while (n >= 0) {
            Object[][] data = {
            {
                addedSong[(n-j)],
            }
        };
            j = j+1;
        }
            n = n +1;

    }
}

Error:

--------------------Configuration: <Default>--------------------
C:\Users\Andrew\Documents\ICS4U Final\jPlayer.java:47: error: cannot find symbol
        final Jtable table = new JTable(data, columnNames);
              ^
  symbol:   class Jtable
  location: class jPlayer
C:\Users\Andrew\Documents\ICS4U Final\jPlayer.java:75: error: cannot find symbol
            dialog.setFileFilter(new FileNameExtensionFiler("Wave File (*.wav)"));
                                     ^
  symbol:   class FileNameExtensionFiler
  location: class jPlayer
2 errors

Process completed.

Sorry for all the questions, thanks for any help!

Edit: I've changed Jtable to JTable, as well as added the t to filter, and gotten rid of the holder since I shouldn't need it anymore.

The code now looks like:

//C:\\Users\\Andrew\\Downloads\\never gonna give you up.wav
//Andrew Douglas
//Imports
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.sound.sampled.*;
import javax.swing.filechooser.*;
import javax.swing.JTable;

//Creates class
public class JPlayer extends JFrame implements ActionListener {

    //Sets up form items and necessary globals
    JButton save, play, stop, loop;
    JFileChooser dialog;

    String Artist, Song, Album, Loc;
    Object[][] data;
    int n = 1;
    //Makes the library, with a 51 song limit.
    jLibrary[] addedSong = new jLibrary[50];

    public JPlayer() {
        //Creates frame
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setTitle("jPlayer");
        this.setSize(800, 600);
        //Makes titles for table
        String[] columnNames =  {"Artist",
                                "Song",
                                "Album",
                                "Location"};
        //Gives one value for array
        addedSong[0] = new jLibrary("Rick Astley", "NGGYU", "UnKnown", "C:\\Users\\Andrew\\Downloads\\never gonna give you up.wav");
        //Adds it to table array
        Object[][] data = {
        {
            addedSong[0]
        }

        };
        //Creates table
        final JTable table = new JTable(data, columnNames);
        table.setPreferredScrollableViewportSize(new Dimension(500, 70));
        table.setFillsViewportHeight(true);
        //Lets it sort the rows
        table.setAutoCreateRowSorter(true);
        //Creates the scroller
        JScrollPane scrollPane = new JScrollPane(table);
        //Makes the save file dialog and the play and save buttons
        dialog = new JFileChooser();
        play = new JButton ("Play Song");
        save = new JButton ("Save a file");
        //Adds the button listeners
        save.addActionListener(this);
        play.addActionListener(this);
        //Adds buttons to panel
        JPanel buttons = new JPanel();
        buttons.add(save);
        buttons.add(play);
        //Puts the buttons at the bottom
        add(buttons, BorderLayout.SOUTH);
        add(scrollPane);
        this.setVisible(true);

    }
    //Creates action listener for button
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == save) {
            dialog.setFileFilter(new FileNameExtensionFilter("Wave File (*.wav)"));
            int returnVal = dialog.showSaveDialog(JPlayer.this);
            if (returnVal == dialog.APPROVE_OPTION) {
                File file = dialog.getSelectedFile();
                addToLibrary("", "", "", file.getName());

            }
        }
        else if (e.getSource() == play) {
            try {
            File soundFile = new File(table.getSelectedRows[3]);
            System.out.println(soundFile);
            AudioInputStream audioIn = AudioSystem.getAudioInputStream(soundFile);
            Clip clip = AudioSystem.getClip();
            clip.open(audioIn);
            clip.start();
            } catch (UnsupportedAudioFileException f) {
         f.printStackTrace();
      } catch (IOException f) {
         f.printStackTrace();
      } catch (LineUnavailableException f) {
         f.printStackTrace();
      }

    } }
    public static void main(String[]args) {
        new jPlayer();
    }
    public void addToLibrary(String art, String song, String alb, String file) {
            addedSong[n] = new jLibrary(art, song, alb, file);
            int j = 0;
            while (n >= 0) {
            Object[][] data = {
            {
                addedSong[(n-j)],
            }
        };
            j = j+1;
        }
            n = n +1;

    }
}

But now I'm getting this error:

--------------------Configuration: <Default>--------------------
C:\Users\Andrew\Documents\ICS4U Final\JPlayer.java:83: error: cannot find symbol
            File soundFile = new File(table.getSelectedRows[3]);
                                      ^
  symbol:   variable table
  location: class JPlayer
1 error

Process completed.

Any help?

Answer 1

In answer to your second question;

Remember that variables defined inside methods can only be used within that method,

final JTable table = new JTable(data, columnNames);

is defined within the constructor public JPlayer() so can't then be used in the public void actionPerformed(ActionEvent e) method. You need to define table as a instance member(i.e. near the top* along with JButton save, play, stop, loop; etc)

*technically instance members don't need to be near the top but they usually are

Answer 2

The class you need is JTable, not Jtable

The error basically means that you are using a symbol that does not exist. The class you are trying to use exists in package javax.swing (that you have imported) : javax.swing.JTable , with a big T

An IDE would have helped you to find it but for a beginner, it is also a good thing to start with just a text editor and see errors one by one ;)

Answer 3

final JTable table = new JTable(data, columnNames);

And not Jtable. Try using eclipse for avoid this kind of problem !

Answer 4

The class is called FileNameExtensionFilter - not FileNameExtensionFiler. (add a 't').

I recommend you to download and use an IDE such as Eclipse or NetBeans. They will assist you in avoiding these typographic errors.