文件正在由另一个进程使用，但是canRead（）返回true

Question

I'm using another program to convert bin files to xml and then I'm trying to read the file. With the following code:

File file = new File(currentPath + "/ammunition.bin");
File file2 = fileTools.convert(file);
ArrayList<String> asd = fileTools.readFile(file2);

I get FileNotFoundException, "file is in use by another process". What makes this weird is that file.canRead() returns true even though i get the exception. Here is the rest of the code:

public ArrayList<String> readFile(File file) {

    ArrayList<String> result = new ArrayList<>();
    Scanner reader;
    try {
        reader = new Scanner(file, "UTF-8");
    } catch (FileNotFoundException ex) {
        boolean b = file.canRead();
        StringWriter errors = new StringWriter();
        ex.printStackTrace(new PrintWriter(errors));
        JOptionPane.showMessageDialog(null, errors.toString());
        alertError("readFile\n" + b + " " + ex.getMessage());
        return null;
    }
    while (reader.hasNext()) {
        result.add(reader.nextLine());
    }
    reader.close();
    return result;
}

public File changeFileExtension(File f, String ext) {
    String name = f.getAbsolutePath();
    int i = name.lastIndexOf(".");
    name = name.substring(0, i) + "." + ext;
    f = new File(name);
    return f;
}


public File convert(File file) {

    File binConverter = new File(this.currentPath + "\\GibbedsTools\\Gibbed.Avalanche.BinConvert.exe");

    if (!binConverter.exists()) {
        alertError("convert\nGibbedsTools is missing, it should be in\n" + this.currentPath + "\\GibbedsTools\\Gibbed.Avalanche.BinConvert.exe");
        return null;
    }

    if (!file.exists()) {
        alertError("convert\nFile does not exist\n" + file.getAbsolutePath());
    }

    String name = file.getName();
    String extension = name.substring(name.lastIndexOf(".") + 1, name.length());

    Runtime rt = Runtime.getRuntime();

    try {
        rt.exec("cmd.exe /c " + "\"\"" + this.currentPath + "\\GibbedsTools\\Gibbed.Avalanche.BinConvert.exe\" \"" + file.getAbsolutePath() + "\"\"");
    } catch (IOException ex) {
        alertError("binToXml\n" + ex.getMessage());
        return null;
    }

    File file2 = changeFileExtension(file, extension.equals("xml") ? "bin" : "xml");

    int timepassed = 0;

    while (!file2.exists() || !file2.canWrite() || timepassed <= 50) {
        try {
            Thread.sleep(50);
        } catch (InterruptedException ex) {
            alertError("binToXml\n" + ex.getMessage());
            return null;
        }
        timepassed += 50;
        if (timepassed > 3000) {
            if (!file2.exists()) {
                alertError("convert\nError, binconverter probably crashed (No xml file created after 3 seconds from passing file to binconverter)\n"
                        + "xml file should be in:\n"
                        + file2.getAbsolutePath() + "     Found: " + file2.exists());
                return null;
            }
        }
        if (timepassed > 6000 && !file2.canWrite()) {
            alertError("convert\nCan't write to the xml file after 6 seconds from passing the file to binconverter."
                    + file2.getAbsolutePath() + "     Can write: " + file2.canWrite());
            return null;
        }
    }

    return file2;
}

Answer 1

instead of having :

Runtime rt = Runtime.getRuntime();
.
.
.

try this instead:

 Process p = Runtime.getRuntime().exec("cmd.exe /c " + "\"\"" + this.currentPath + "\\GibbedsTools\\Gibbed.Avalanche.BinConvert.exe\" \"" + file.getAbsolutePath() + "\"\"");

then you can wait for it to finish by using:

p.waitFor();

once external program finishes it then releases the file. better solution would be using Processbuilder

You can also destroy the process by using

p.destroy();

of course try to avoid using it. unless program is pain to deal with.