JAVA: file:/tmp/guest-u9uIBd/Schreibtisch/Untitled.jar!/ressources/db_config.conf (file not found)

Question

When I try to open an entry in my compiled .jar file, I get the following error (translated from german to english ;)):

java.io.FileNotFoundException: file:/tmp/guest-u9uIBd/Schreibtisch/Untitled.jar!/ressources/db_config.conf (file not found)
at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(FileInputStream.java:195)
at java.io.FileInputStream.<init>(FileInputStream.java:138)
at java.io.FileInputStream.<init>(FileInputStream.java:93)
at java.io.FileReader.<init>(FileReader.java:58)
at application.ConnectionProperties.ReadConnectionProperties(ConnectionProperties.java:23)
at application.MainController.ReadConfigFile(MainController.java:218)
at application.MainController.initialize(MainController.java:68)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3214)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
at application.Main.start(Main.java:15)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$163(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$176(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null$174(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$175(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
at com.sun.glass.ui.gtk.GtkApplication.lambda$null$50(GtkApplication.java:139)
at java.lang.Thread.run(Thread.java:745)

Starting application!

Here is the code:

private void ReadConfigFile() {
    try {           cp.ReadConnectionProperties(this.getClass().getResource("/ressources/db_config.conf"), dbhost1,
                dbport1, dbusername1, dbpasswd1, dbname1);
    } catch (IOException e1) {
        e1.printStackTrace();
    }
}

and

public void ReadConnectionProperties(URL string, TextField dbhost1, TextField dbport1, TextField dbusername1, TextField dbpasswd1,TextField dbname1) throws IOException {
    String host, port, uname, password, name;
    /** */
    FileReader fr = new FileReader(string.getFile());
    BufferedReader br = new BufferedReader(fr);

    host = br.readLine();
    port = br.readLine();
    uname = br.readLine();
    password = br.readLine();
    name = br.readLine();

    dbhost1.setText(host);
    dbport1.setText(port);
    dbusername1.setText(uname);
    dbpasswd1.setText(password);
    dbname1.setText(name);

    br.close();
}

The Folder /ressources/ and the file db_config.conf existed in the .jar file and in the project. He show me only the error, when I want to start the jar. When I start the project in eclipse, he say me no error.

Please help me

Answer 1

The message is correct: you do not have a file named /tmp/guest-u9uIBd/Schreibtisch/Untitled.jar!/ressources/db_config.conf on your computer. The URL you obtained from Class.getResource() refers to an entry inside a jar file. It can not be read using FileReader.

You must use the URL.openStream() method to obtain an input stream from which you can read the contents of that entry. Or use Class.getResourceAsStream() to save a step.

When you ran your project in eclipse, the reason it did not fail is because the classpath entry that contained the file was a directory, and so the URL returned by Class.getResource() just happened to be a file on the local filesystem. When you package your program in a jar file, then the resource you are looking for is inside a jar rather than a local file. Using URL.openStream() will work in both situations.

public void ReadConnectionProperties(URL url, TextField dbhost1, TextField dbport1, TextField dbusername1, TextField dbpasswd1,TextField dbname1) throws IOException {
    String host, port, uname, password, name;
    /** */
    try ( final InputStream stream = url.openStream();
          final Reader reader = new InputStreamReader(stream);
          final BufferedReader br = new BufferedReader(reader); )
        {
        host = br.readLine();
        port = br.readLine();
        uname = br.readLine();
        password = br.readLine();
        name = br.readLine();

        dbhost1.setText(host);
        dbport1.setText(port);
        dbusername1.setText(uname);
        dbpasswd1.setText(password);
        dbname1.setText(name);
        }

See also try-with-resources.