' Exception in Application start method, java.

Question

I am attempting to read values from MySQL database and display it in a table in JavaFX. I use netbeans IDE. When I run my code I got the exception mentioned in the title. I will post code below:

public class ViewSubject extends Application {

private final TableView<Subject> table = new TableView<>();
private final ObservableList<Subject> data
        = FXCollections.observableArrayList();
final HBox hb = new HBox();

private Connection connect = null;
private Statement statement = null;
private final PreparedStatement preparedStatement = null;
private ResultSet resultSet = null;

public static void main(String[] args) {
    launch(args);
}

@Override
public void start(Stage stage) throws ClassNotFoundException, SQLException {

    Scene scene = new Scene(new Group());
    stage.setTitle("Add Subject");
    stage.setWidth(650);
    stage.setHeight(550);
    stage.setResizable(false);

    final Label label = new Label("Subject Details");
    label.setFont(new Font("Calibri", 20));

    TableColumn sub = new TableColumn("Subject Name");
    sub.setMinWidth(350);
    sub.setCellValueFactory(
            new PropertyValueFactory<Subject, String>("subName"));
    sub.setCellFactory(TextFieldTableCell.forTableColumn());
    sub.setOnEditCommit(
            new EventHandler<TableColumn.CellEditEvent<Subject, String>>() {
                @Override
                public void handle(TableColumn.CellEditEvent<Subject, String> t) {
                    ((Subject) t.getTableView().getItems().get(
                            t.getTablePosition().getRow())).setSubName(t.getNewValue());
                }
            }
    );

    TableColumn code = new TableColumn("Subject Code");
    code.setMinWidth(130);
    code.setCellValueFactory(
            new PropertyValueFactory<Subject, String>("subCode"));
    code.setCellFactory(TextFieldTableCell.forTableColumn());
    code.setCellFactory(TextFieldTableCell.forTableColumn());
    code.setOnEditCommit(
            new EventHandler<TableColumn.CellEditEvent<Subject, String>>() {
                @Override
                public void handle(TableColumn.CellEditEvent<Subject, String> t) {
                    ((Subject) t.getTableView().getItems().get(
                            t.getTablePosition().getRow())).setSubCode(t.getNewValue());
                }
            }
    );

    TableColumn rev = new TableColumn("Revision");
    rev.setMinWidth(130);
    rev.setCellValueFactory(
            new PropertyValueFactory<Subject, String>("subRev"));
    rev.setCellFactory(TextFieldTableCell.forTableColumn());
    rev.setCellFactory(TextFieldTableCell.forTableColumn());
    rev.setOnEditCommit(
            new EventHandler<TableColumn.CellEditEvent<Subject, String>>() {
                @Override
                public void handle(TableColumn.CellEditEvent<Subject, String> t) {
                    ((Subject) t.getTableView().getItems().get(
                            t.getTablePosition().getRow())).setSubCode(t.getNewValue());
                }
            }
    );

    table.setItems(data);
    table.getColumns().addAll(sub, code, rev);

    final VBox vbox = new VBox();
    vbox.setSpacing(10);
    vbox.setPadding(new Insets(20, 20, 20, 20));
    vbox.getChildren().addAll(label, table);

    ((Group) scene.getRoot()).getChildren().addAll(vbox);

    stage.setScene(scene);
    stage.show();

    try {
        Class.forName("com.mysql.jdbc.Driver");
        connect = DriverManager
                .getConnection("jdbc:mysql://localhost:3306/project?"
                        + "user=root&password=virus");
        statement = connect.createStatement();

        resultSet = statement
                .executeQuery("select * from subject");
        writeResultSet(resultSet);
    } catch (ClassNotFoundException | SQLException e) {
        throw e;
    } finally {
        close();
    }

}

private void writeResultSet(ResultSet resultSet) throws SQLException {

    while (resultSet.next()) {

        String subname = resultSet.getString("subname");
        String code = resultSet.getString("subcode");
        String rev = resultSet.getString("subrev");

        data.add(new Subject(subname, code, rev));
    }
}

private void close() {
    try {
        if (resultSet != null) {
            resultSet.close();
        }
        if (statement != null) {
            statement.close();
        }
        if (connect != null) {
            connect.close();
        }
    } catch (SQLException e) {

    }
}
}

There is one more class in the package -

public class Subject {

    private final SimpleStringProperty sub;
    private final SimpleStringProperty code;
    private final SimpleStringProperty rev;

    Subject(String subName, String subCode, String subRev) {
        this.sub = new SimpleStringProperty(subName);
        this.code = new SimpleStringProperty(subCode);
        this.rev = new SimpleStringProperty(subRev);
    }

    public String getSubName() {
        return sub.get();
    }

    public void setSubName(String subName) {
        sub.set(subName);
    }

    public String getSubCode() {
        return code.get();
    }

    public void setSubCode(String subCode) {
        code.set(subCode);
    }

    public String getSubRev() {
        return rev.get();
    }

    public void setSubRev(String subRev) {
        rev.set(subRev);
    }
}

This is the exception details:

Exception in Application start method
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.javafx.main.Main.launchApp(Main.java:698)
at com.javafx.main.Main.main(Main.java:871)
Caused by: java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:403)
at com.sun.javafx.application.LauncherImpl.access$000(LauncherImpl.java:47)
at com.sun.javafx.application.LauncherImpl$1.run(LauncherImpl.java:115)
at java.lang.Thread.run(Thread.java:744)
Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:190)
at viewsubject.ViewSubject.read(ViewSubject.java:119)
at viewsubject.ViewSubject.start(ViewSubject.java:113)
at com.sun.javafx.application.LauncherImpl$5.run(LauncherImpl.java:319)
at com.sun.javafx.application.PlatformImpl$5.run(PlatformImpl.java:216)
at com.sun.javafx.application.PlatformImpl$4$1.run(PlatformImpl.java:179)
at com.sun.javafx.application.PlatformImpl$4$1.run(PlatformImpl.java:176)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl$4.run(PlatformImpl.java:176)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:76)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:17)
at com.sun.glass.ui.win.WinApplication$3$1.run(WinApplication.java:67)
... 1 more

When the code is ran, a window appears for a fraction of a second and then suddenly closes due to the occurrence of this exception. Why this exception occurs ? How can remove this exception?

Answer 1

You don't have the MySQL JDBC driver on your classpath.

Perform the Vogella tutorial on Java and JDBC with MySQL. Do the whole tutorial step by step, running code each step of the way. As part of the Vogella tutorial, it tells you how to setup 3rd party libraries (like the MySQL JDBC library) in Eclipse.

When posting code, try to post code which matches the stack trace. The StackTrace reports an error at viewsubject.ViewSubject.read(ViewSubject.java:119) but there is no such read function in your ViewSubject class.