我是Java的新手，我在编译时遇到错误，特别是“无法找到符号错误”。我正在尝试将表中的字符串作为文件目的地进入，但我无法调用表，所以我尝试使用变量holder，只是为了再次出错。
与此同时，我试图更改可以在filechooser上打开的文件类型，但我找不到可行的解决方案。
最后，有人可以解释一下缺少的符号是什么吗？因为我觉得我误解了它，因为我试图多次修复它而没有成功。
//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.
对不起所有问题，感谢您的帮助！
编辑：我已经将Jtable更改为JTable，并将t添加到过滤器中，并且因为我不再需要它而摆脱了持有者。
现在代码如下：
//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.
任何帮助？
答案 0 :(得分：6)
您需要的课程是JTable，而不是Jtable
错误基本上意味着您使用的是不存在的符号。您尝试使用的课程位于package javax.swing（您已导入）：javax.swing.JTable，其中包含大T
IDE可以帮助您找到它，但对于初学者来说，从一个文本编辑器开始并逐个查看错误也是一件好事;）
答案 1 :(得分：1)
该类称为FileNameExtensionFilter - 而不是FileNameExtensionFiler。 （加't'）。
我建议您下载并使用Eclipse或NetBeans等IDE。它们将帮助您避免这些印刷错误。
答案 2 :(得分：0)
final JTable table = new JTable(data, columnNames);
而不是Jtable。尝试使用eclipse来避免这种问题！
答案 3 :(得分：0)
回答你的第二个问题;
请记住，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public JPlayer()中定义，因此无法在public void actionPerformed(ActionEvent e)方法中使用。您需要将表定义为instance member（即靠近顶部*以及JButton save, play, stop, loop;等）
*技术上，实例成员不需要靠近顶部，但它们通常是