I'm programming a template method design pattern example program with JavaFX, and I can't connect with my MySQL Database. I'm using IntelliJ and I added the MySQL-Connector.jar to the library, but nevertheless I get ClassNotFoundException.
Error
java.lang.ClassNotFoundException: com.mysql.jdbc.driver
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:375)
at sample.DatabaseOperation.openConnection(DatabaseOperation.java:24)
at sample.DatabaseOperation.template(DatabaseOperation.java:14)
at sample.Controller.initialize(Controller.java:44)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2655)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3331)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3287)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3255)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3227)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3203)
at javafx.fxml/javafx.fxml.FXMLLoader.load(FXMLLoader.java:3196)
at sample.Main.start(Main.java:13)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:847)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:484)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:457)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:456)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:184)
at java.base/java.lang.Thread.run(Thread.java:833)
Exception in Application start method
java.lang.reflect.InvocationTargetException
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:465)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:364)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1071)
Caused by: java.lang.RuntimeException: Exception in Application start method
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:901)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:196)
at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: javafx.fxml.LoadException:
/C:/Users/grego/Downloads/code-with-quarkus/TemplateMethodExample/out/production/TemplateMethodExample/sample/sample.fxml
at javafx.fxml/javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2707)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2685)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3331)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3287)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3255)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3227)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3203)
at javafx.fxml/javafx.fxml.FXMLLoader.load(FXMLLoader.java:3196)
at sample.Main.start(Main.java:13)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:847)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:484)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:457)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:456)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:184)
... 1 more
Caused by: java.lang.NullPointerException: Cannot invoke "java.sql.Connection.createStatement()" because "this.connection" is null
at sample.InitialLoad.select(InitialLoad.java:10)
at sample.DatabaseOperation.template(DatabaseOperation.java:17)
at sample.Controller.initialize(Controller.java:44)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2655)
... 17 more
Exception running application sample.Main
Process finished with exit code 1
Template Method
package sample;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
public abstract class DatabaseOperation {
public Connection connection;
public ResultSet resultSet;
public final ResultSet template() throws SQLException {
openConnection();
insert();
update();
select();
closeConnection();
return resultSet;
}
public final void openConnection() {
try {
Class.forName("com.mysql.jdbc.driver");
connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/employees", "user", "password");
} catch (ClassNotFoundException | SQLException e) {
e.printStackTrace();
}
}
public final void closeConnection(){
try {
connection.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
System.out.println("Connection closed");
}
public abstract void select() throws SQLException;
public abstract void insert();
public abstract void update();
}
Class that extends the template
package sample;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class InitialLoad extends DatabaseOperation {
@Override
public void select() throws SQLException {
Statement statement = connection.createStatement();
resultSet = statement.executeQuery("select * from employees");
}
@Override
public void insert() {
}
@Override
public void update() {
}
}
Controller
package sample;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.PropertyValueFactory;
import javax.xml.crypto.Data;
import java.net.URL;
import java.sql.SQLException;
import java.util.ResourceBundle;
public class Controller implements Initializable {
public TableColumn col_emp_no;
public TableColumn col_birth_date;
public TableColumn col_first_name;
public TableColumn col_last_name;
public TableColumn col_gender;
public TableColumn col_hire_date;
@FXML
TableView tableView;
@Override
public void initialize(URL url, ResourceBundle resourceBundle) {
col_emp_no.setCellValueFactory(new PropertyValueFactory<>("emp_no"));
col_birth_date.setCellValueFactory(new PropertyValueFactory<>("birth_date"));
col_first_name.setCellValueFactory(new PropertyValueFactory<>("first_name"));
col_last_name.setCellValueFactory(new PropertyValueFactory<>("last_name"));
col_gender.setCellValueFactory(new PropertyValueFactory<>("gender"));
col_hire_date.setCellValueFactory(new PropertyValueFactory<>("hire_date"));
DatabaseOperation initialLoad = new InitialLoad();
try {
initialLoad.template();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
}
}
Main
package sample;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class Main extends Application {
@Override
public void start(Stage primaryStage) throws Exception{
Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
primaryStage.setTitle("Hello World");
primaryStage.setScene(new Scene(root, 300, 275));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
Thank you in advance!
UPDATE:
I still get the same error when using Maven
[INFO]
[INFO] --- javafx-maven-plugin:0.0.6:run (default-cli) @ TemplateMethodMaven ---
[INFO] Toolchain in javafx-maven-plugin null
java.lang.ClassNotFoundException: com.mysql.jdbc.driver
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:182)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:375)
at org.example.DatabaseOperation.openConnection(DatabaseOperation.java:24)
at org.example.DatabaseOperation.template(DatabaseOperation.java:14)
at org.example.PrimaryController.initialize(PrimaryController.java:44)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2655)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
at javafx.fxml/javafx.fxml.FXMLLoader.load(FXMLLoader.java:2516)
at org.example.App.loadFXML(App.java:31)
at org.example.App.start(App.java:20)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:847)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:484)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:457)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:456)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:184)
at java.base/java.lang.Thread.run(Thread.java:831)
Exception in Application start method
java.lang.reflect.InvocationTargetException
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:465)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:364)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:567)
at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1071)
Caused by: java.lang.RuntimeException: Exception in Application start method
at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:901)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:196)
at java.base/java.lang.Thread.run(Thread.java:831)
Caused by: javafx.fxml.LoadException:
/C:/Users/grego/Downloads/code-with-quarkus/TemplateMethodMaven/target/classes/org/example/primary.fxml
at javafx.fxml/javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2707)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2685)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
at javafx.fxml/javafx.fxml.FXMLLoader.load(FXMLLoader.java:2516)
at org.example.App.loadFXML(App.java:31)
at org.example.App.start(App.java:20)
at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:847)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:484)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:457)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:456)
at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:184)
... 1 more
Caused by: java.lang.NullPointerException: Cannot invoke "java.sql.Connection.createStatement()" because "this.connection" is null
at org.example.InitialLoad.select(InitialLoad.java:10)
at org.example.DatabaseOperation.template(DatabaseOperation.java:17)
at org.example.PrimaryController.initialize(PrimaryController.java:44)
at javafx.fxml/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2655)
... 13 more
Exception running application org.example.App
[ERROR] Command execution failed.
org.apache.commons.exec.ExecuteException: Process exited with an error: 1 (Exit value: 1)
at org.apache.commons.exec.DefaultExecutor.executeInternal (DefaultExecutor.java:404)
at org.apache.commons.exec.DefaultExecutor.execute (DefaultExecutor.java:166)
at org.openjfx.JavaFXBaseMojo.executeCommandLine (JavaFXBaseMojo.java:567)
at org.openjfx.JavaFXBaseMojo.executeCommandLine (JavaFXBaseMojo.java:434)
at org.openjfx.JavaFXRunMojo.execute (JavaFXRunMojo.java:105)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:77)
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke (Method.java:568)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
at org.codehaus.classworlds.Launcher.main (Launcher.java:47)
org.apache.commons.exec.ExecuteException: Process exited with an error: 1 (Exit value: 1)
at org.apache.commons.exec.DefaultExecutor.executeInternal(DefaultExecutor.java:404)
at org.apache.commons.exec.DefaultExecutor.execute(DefaultExecutor.java:166)
at org.openjfx.JavaFXBaseMojo.executeCommandLine(JavaFXBaseMojo.java:567)
at org.openjfx.JavaFXBaseMojo.executeCommandLine(JavaFXBaseMojo.java:434)
at org.openjfx.JavaFXRunMojo.execute(JavaFXRunMojo.java:105)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:137)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:210)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:156)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:148)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:117)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:81)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build(SingleThreadedBuilder.java:56)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:305)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:192)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:105)
at org.apache.maven.cli.MavenCli.execute(MavenCli.java:957)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:289)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:193)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:282)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:225)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:406)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:347)
at org.codehaus.classworlds.Launcher.main(Launcher.java:47)
See this guide for Idea JavaFX project setup, specifically refer to the section on adding additional modules.
The maven module for the mysql JDBC connector you need to add:
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.28</version>
</dependency>
If you don't provide a module-info.java, your app code will be on the class path and the mysql connector will also be on the class path, so access should work without additional changes.
If you provide a module-info.java you will need to require the appropriate modules in your module-info.java:
requires java.sql for the standard jdbc and sql access code.requires mysql.connector.java for the mysql jdbc driver.Example module-info.java (replace the module name and modify requirement clauses as needed):
module com.example.sql {
requires javafx.controls;
requires javafx.fxml;
requires mysql.connector.java;
requires java.sql;
opens com.example.sql to javafx.fxml;
exports com.example.sql;
}
When you attempt to open a database connection you have this code which is both wrong and unnecessary for multiple reasons:
Class.forName("com.mysql.jdbc.driver");
Once, the access is correctly configured by adding the right library and module commands, the execution of this line results in the following warning:
Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
So both:
the driver name is wrong, it should be com.mysql.cj.jdbc.Driver
AND
you don't need to explicitly load the driver
The jdbc system will load it automatically as needed through the service provider interface. The SPI is complicated, you don't have to worry about how it actually works, just assume it does.
More info is in the answer to:
Following the Oracle jdbc tutorial, you get connection code like this:
public Connection getConnection() throws SQLException {
Properties connectionProps = new Properties();
connectionProps.put("user", "apple");
connectionProps.put("password", "cider");
Connection conn = DriverManager.getConnection(
"jdbc:mysql://localhost:1433/",
connectionProps
);
System.out.println("Connected to database");
return conn;
}
Calling this method from the start method appeared to attempt to initiate a connection for me (it didn't actually connect because I don't have a local mysql server set up).