W debuggerze program zatrzymuję się na tej linijce
ResultSet result = statement.executeQuery("select FIRST_NAME, LAST_NAME from EMPLOYEE");
i nie idzie dalej, nie wchodzi w pętle, pytanie dlaczego ? I dlatego później otrzymuję informację o wskazaniu na pustą listę ?
public List<ModelEmployee> readAllEmployees(){
List<ModelEmployee> employees = new LinkedList<ModelEmployee>();
try{
ResultSet result = statement.executeQuery("select FIRST_NAME, LAST_NAME from EMPLOYEE");
//ResultSet result = statement.executeQuery("SELECT * FROM EMPLOYEE");
int EMP_NO;
String firstName, lastName;
String jobCode;
Date hireDate;
String jobCountry;
double salary;
while(result.next()){
//EMP_NO = result.getInt("EMP_NO");
firstName = result.getString("FIRST_NAME");
lastName = result.getString("LAST_NAME");
//jobCode = result.getString("JOB_CODE");
//jobCountry = result.getString("JOB_COUNTRY");
//hireDate = result.getDate("HIRE_DATE");
//salary = result.getDouble("SALARY");
employees.add(new ModelEmployee(firstName, lastName));
}
}catch(SQLException ex){
JOptionPane.showMessageDialog(null, "Nie udało się pobrać danych " +ex);
return null;
}
return employees;
}
@Override
public void actionPerformed(ActionEvent ae) {
if(ae.getActionCommand().equals("Pokaż")){
CommunicationDB cDB = new CommunicationDB();
List<ModelEmployee> listOfEmployees = cDB.readAllEmployees();
for(int i=0; i<listOfEmployees.size(); i++){
System.out.println(listOfEmployees.get(i).getFirstName());
}
/*String person="";
for(int i=0; i<listOfEmployees.size(); i++){
person += Integer.toString(listOfEmployees.get(i).getEMP_NO());
person += " " + listOfEmployees.get(i).getFirstName();
jTAField.append(person);
}*/
cDB.closeConnection();
}
else if(ae.getActionCommand().equals("Wyłącz")){
}
}
public class CommunicationDB {
public static final String DRIVER = "org.firebirdsql.jdbc.FBDriver";
private Connection conn;
private Statement statement;
public CommunicationDB(){
try {
Class.forName(CommunicationDB.DRIVER);
} catch (ClassNotFoundException ex) {
JOptionPane.showMessageDialog(null, "Brak sterownika " + ex);
}
//łączenie z bazą danych
try{
conn = DriverManager.getConnection("jdbc:firebirdsql://localhost/E:/EMPLOYEE.FDB", "SYSDBA", "masterkey");
}catch(SQLException ex){
JOptionPane.showMessageDialog(null, "Problem z otwarciem połączenia. "+ ex);
}
}
Błędy:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at zlabemployee.CommunicationDB.readAllEmployees(CommunicationDB.java:51)
at zlabemployee.Window.actionPerformed(Window.java:81)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
at java.awt.Component.processMouseEvent(Component.java:6505)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3320)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2719)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:694)
at java.awt.EventQueue$3.run(EventQueue.java:692)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:708)
at java.awt.EventQueue$4.run(EventQueue.java:706)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)
dodanie znacznika <code class="java"> - fp