2

我是 Java 新手，在编译时不断出现错误，尤其是“找不到符号错误”。我试图让表中的字符串作为文件目标进入，但我无法调用表，所以我尝试使用变量持有者，只是再次出现错误。

除此之外，我试图更改可以在文件选择器上打开哪些类型的文件，但我找不到可行的解决方案。

最后，有人能解释一下缺失的符号是什么吗？因为我觉得我误解了它，因为我试图修复它很多次都没有成功。

//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;

    }
}

错误：

--------------------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.

抱歉所有问题，感谢您的帮助！

编辑：我已将 Jtable 更改为 JTable，并将 t 添加到过滤器，并摆脱了持有人，因为我不再需要它了。

代码现在看起来像：

//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;

    }
}

但现在我收到了这个错误：

--------------------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.

有什么帮助吗？

4

4 回答 4

6

你需要的课程是JTable，不是Jtable

该错误基本上意味着您使用的符号不存在。您尝试使用的类存在于package javax.swing（您已导入）:javax.swing.JTable中，有一个大T

IDE 可以帮助您找到它，但对于初学者来说，仅从文本编辑器开始并逐个查看错误也是一件好事；）

于 2013-06-18T12:19:45.773 回答
1

该类被称为FileNameExtensionFilter- not FileNameExtensionFiler。（添加一个't'）。

我建议您下载并使用 IDE，例如 Eclipse 或 NetBeans。他们将帮助您避免这些印刷错误。

于 2013-06-18T12:19:29.900 回答
0 
final JTable table = new JTable(data, columnNames);

而不是Jtable。尝试使用 eclipse 来避免这种问题！

于 2013-06-18T12:22:02.273 回答
0

回答你的第二个问题；

请记住，在方法中定义的变量只能在该方法中使用，

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

在构造函数中定义，public JPlayer()因此不能在public void actionPerformed(ActionEvent e)方法中使用。您需要将表定义为实例成员（即靠近顶部*JButton save, play, stop, loop;等）

*从技术上讲，实例成员不需要靠近顶部，但它们通常是

于 2013-06-18T12:34:44.900 回答