Question

单击按钮时，我尝试使用JFileChooser保存文件。因此，当我单击它时，窗口将如预期的那样出现，然后放入文件名并保存。一切正常，我将文件放置在确切的位置，并根据需要将文件保存在.txt中，但是当我打开文件时，什么也没有。我已经测试过书写和打印，但是没有任何效果。所以我想知道我在哪里错了，应该怎么做。

谢谢！

这是我的代码：

jbSave.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        JFileChooser fileChooser = new JFileChooser();
        if (fileChooser.showSaveDialog(null) == JFileChooser.APPROVE_OPTION) {
            File file = fileChooser.getSelectedFile();
            try {
                String path = file.getPath() + ".txt";
                file = new File(path);
                FileWriter filewriter = new FileWriter(file.getPath(), true);
                BufferedWriter buff = new BufferedWriter(filewriter);
                PrintWriter writer = new PrintWriter(buff);
                writer.write("start");                                      
            } catch (FileNotFoundException e2) {
                e2.printStackTrace();
            } catch (IOException e1) {
                e1.printStackTrace();
            }
        }       
    }           
});

Answer 1

只需向this answer添加更多详细信息或替代方法，就可以使用try-with-resource块，并让JVM为您关闭（并刷新）编写器。

try(PrintWriter writer = ...))
{
    writer.write("start");
} 
catch (IOException e) 
{
    // Handle exception.
}

此外，您可以编写实用程序函数来创建PrintWriter：

/**
 * Opens the file for writing, creating the file if it doesn't exist. Bytes will
 * be written to the end of the file rather than the beginning.
 *
 * The returned PrintWriter uses a BufferedWriter internally to write text to
 * the file in an efficient manner.
 *
 * @param path
 *            the path to the file
 * @param cs
 *            the charset to use for encoding
 * @return a new PrintWriter
 * @throws IOException
 *             if an I/O error occurs opening or creating the file
 * @throws SecurityException
 *             in the case of the default provider, and a security manager is
 *             installed, the checkWrite method is invoked to check write access
 *             to the file
 * @see Files#newBufferedWriter(Path, Charset, java.nio.file.OpenOption...)
 */
public static PrintWriter newAppendingPrintWriter(Path path, Charset cs) throws IOException
{
    return new PrintWriter(Files.newBufferedWriter(path, cs, CREATE, APPEND, WRITE));
}

如果所有数据都可以在一个操作中写入，则另一种可能性是使用Files.write()：

try 
{
    byte[] bytes = "start".getBytes(StandardCharsets.UTF_8);
    Files.write(file.toPath(), bytes)
} 
catch (IOException e) 
{
    // Handle exception.
}

Answer 2

问题是您没有关闭PrintWriter实例。完成这样的编写后，只需关闭PrintWriter即可解决问题：

writer.close();

使用JFileChooser

2 个答案: