Guten Morgen, ich verzweifle seit gestern an einem Fehler der immer dann auftritt wenn ich die Parameter einer JProgressBar bzw. eines JButtons in einem Try/catch block ändern möchte.
Fehler:
Fehler:
Java:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at MainFrame.verbindung(MainFrame.java:47)
at MainFrame$2.actionPerformed(MainFrame.java:148)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Java:
public class MainFrame {
private JFrame frame;
private JTextField dbip;
private JTextField dbusername;
private JPasswordField dbpassword;
private JButton connect;
private JProgressBar ladebalken;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
MainFrame window = new MainFrame();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public void verbindung() {
try
{
Class.forName( "com.mysql.jdbc.Driver" );
ladebalken.setValue(10);
Connection con = DriverManager.getConnection("jdbc:mysql://localhost/test", "root", "admin");
ladebalken.setValue(30);
Statement stmt = con.createStatement();
ladebalken.setValue(60);
String am = "Select * from kunde";
ladebalken.setValue(80);
ResultSet rst = stmt.executeQuery(am);
ladebalken.setValue(100);
connect.setBackground(Color.GREEN);
while (rst.next()) {
System.out.println(rst.getString("Vorname"));
}
rst.close();
stmt.close();
con.close();
}
catch ( ClassNotFoundException e)
{
System.out.println("Blöd, geht nicht") ;
e.printStackTrace();
}
catch ( SQLException e)
{
System.out.println("SQL Fehler");
e.printStackTrace();
}
}