我试图从MySQL数据库中读取值并将其显示在JavaFX的表中。我使用netbeans IDE。当我运行我的代码时，我得到了标题中提到的异常。我将在下面发布代码：
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) {
}
}
}
包中还有一个类 -
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);
}
}
这是例外情况：
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
当代码运行时，窗口会出现几分之一秒，然后由于此异常的发生而突然关闭。为什么会发生此异常？如何删除此异常？
答案 0 :(得分：1)
您的类路径中没有MySQL JDBC driver。
在Java and JDBC with MySQL上执行Vogella教程。一步一步地完成整个教程，每一步都运行代码。作为Vogella教程的一部分，它告诉您如何在Eclipse中setup 3rd party libraries（如MySQL JDBC库）。
发布代码时，尝试发布与堆栈跟踪匹配的代码。 StackTrace在viewsubject.ViewSubject.read（ViewSubject.java:119）上报告错误，但在ViewSubject类中没有这样的读取函数。