Question

我有一个应用程序来创建数据的图形表示。我在JFreeCharts方法上使用此方法来使用lists参数创建图表。我需要处理从JFileChooser返回的文件。这是我的班级：

public class ReadGCFile {
static File theFile;
static JFileChooser fileChooser = new JFileChooser();
static JButton theButton = new JButton("Choose the file to represent");

public static void readGCList(List<String> gcArrayList,
        List<String> gcStringList, List<String> gcDateList)
        throws NumberFormatException, IOException, ParseException {
    String line = "";
    String[] tokens = null;
    FileReader fr = null;
    BufferedReader bufReader = null;

    theButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent event) {

            int returnValue = fileChooser.showOpenDialog(null);
            if (returnValue == JFileChooser.APPROVE_OPTION) {
                theFile = fileChooser.getSelectedFile();

            }
        }
    });

    try {

        fr = new FileReader(theFile);

        bufReader = new BufferedReader(fr);
        while ((line = bufReader.readLine()) != null) {
            line = line.replace(",", ".");
            tokens = line.split(";");

            gcDateList.add(tokens[0]);
            gcStringList.add(tokens[1]);
            gcArrayList.add(tokens[2]);
            gcArrayList.add(tokens[3]);
            gcArrayList.add(tokens[4]);

        }

    } catch (FileNotFoundException es) {
        System.out.println("The file was not found.");

    } catch (NullPointerException e) {
        System.out.println("No files were chosen !");
    }

    catch (IOException e) {

        bufReader.close();

    }

    for (int i = 0; i < gcDateList.size(); i++) {
        SimpleDateFormat currentFormat = new SimpleDateFormat(
                "yyyy-MM-dd hh:mm:ss");
        SimpleDateFormat convertedFormat = new SimpleDateFormat(
                "dd MMM hh:mm:ss");

        gcDateList.set(i, convertedFormat.format(currentFormat
                .parse(gcDateList.get(i))));

    }

}

}

如何从按钮的actionlistener中保留“theFile”的值。在“try”块中，“theFile”为空。

Answer 1

仅当您拥有文件时，即在 actionPerformed 方法中处理文件。

示例：

将所有处理逻辑放在一个方法中：

private static void processFile(File theFile, List<String> gcArrayList,
        List<String> gcStringList, List<String> gcDateList){

    String line = "";
    String[] tokens = null;
    FileReader fr = null;
    BufferedReader bufReader = null;

   try {

        fr = new FileReader(theFile);

        bufReader = new BufferedReader(fr);
        while ((line = bufReader.readLine()) != null) {
            line = line.replace(",", ".");
            tokens = line.split(";");

            gcDateList.add(tokens[0]);
            gcStringList.add(tokens[1]);
            gcArrayList.add(tokens[2]);
            gcArrayList.add(tokens[3]);
            gcArrayList.add(tokens[4]);

        }

    } catch (FileNotFoundException es) {
        System.out.println("The file was not found.");

    } catch (NullPointerException e) {
        System.out.println("No files were chosen !");
    }

    catch (IOException e) {

        bufReader.close();

    }

    for (int i = 0; i < gcDateList.size(); i++) {
        SimpleDateFormat currentFormat = new SimpleDateFormat(
                "yyyy-MM-dd hh:mm:ss");
        SimpleDateFormat convertedFormat = new SimpleDateFormat(
                "dd MMM hh:mm:ss");

        gcDateList.set(i, convertedFormat.format(currentFormat
                .parse(gcDateList.get(i))));

    }

}

然后，从actionPerformed方法调用它：

theButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent event) {

            int returnValue = fileChooser.showOpenDialog(null);
            if (returnValue == JFileChooser.APPROVE_OPTION) {
                theFile = fileChooser.getSelectedFile();
                processFile(theFile,gcArrayList,gcStringList,gcDateList);

            }
        }
    });

此外，根据您的需要，您可以考虑重置两个文件处理之间的列表。

如何在Java中处理从JFileChooser返回的文件

1 个答案: