get a date using a JDateChooser and save it into mysql database - java

I need to read a date from a JDateChooser and save it into a MYSQL database table using the ActionPerformed method of a JButton.
There are three JDateChoosers called LETTER_DATE , RECEIVED_DATE , SENDING_DATE in this JInternalFrameForm called LETTER .
Below is the code of the ActionPerformed method of the JButton SAVE which will save the data into the MYSQL table.
private void SAVEActionPerformed(java.awt.event.ActionEvent evt) {
try{
Statement s=DB.getConnection().createStatement();
s.executeUpdate("insert into LETTER values('"+LETTER_ID.getText()+"','"+LETTER_CATEGORY.getSelectedItem()+"','"+LETTER_DATE.getDate()+"','"+HEADING.getText()+"','"+SECTION_ID.getSelectedItem()+"','"+SUBJECT_ID.getSelectedItem()+"','"+INSTITUTE_ID.getSelectedItem()+"','"+NEW_INSTITUTE.getText()+"','"+SENDERS_ID.getSelectedItem()+"','"+NEW_SENDER.getText()+"','"+RECEIVED_DATE.getDate()+"','"+RECEIVERS_ID.getSelectedItem()+"','"+NEW_RECEIVER.getText()+"','"+SENDING_DATE.getDate()+"')");
JOptionPane.showMessageDialog(this, "Saved");
}
catch(Exception ex){
ex.printStackTrace();
}
}
When I clicked the JButton to save the data, it gives the following stacktrace.
com.mysql.jdbc.MysqlDataTruncation: Data truncation: Incorrect datetime value: 'Mon Dec 04 14:45:36 PST 2017' for column 'LETTER_DATE' at row 1
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4118)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4052)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2503)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2664)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2788)
at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1816)
at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1730)
at Viewer.LETTER.SAVEActionPerformed(LETTER.java:280)
at Viewer.LETTER.access$000(LETTER.java:16)
at Viewer.LETTER$1.actionPerformed(LETTER.java:99)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$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:6516)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6281)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4872)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4698)
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:4698)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:747)
at java.awt.EventQueue.access$300(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:706)
at java.awt.EventQueue$3.run(EventQueue.java:704)
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:720)
at java.awt.EventQueue$4.run(EventQueue.java:718)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:717)
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)
Can anyone please help me to figure out the problem here and correct the datetime value for column ['LETTER_DATE'][1] at row 1?

Well, you should be using getDateFormatString() instead of getDate(). For instance:
s.executeUpdate("insert into LETTER values('"+LETTER_ID.getText()+"','"+LETTER_CATEGORY.getSelectedItem()+"','"+LETTER_DATE.getDateFormatString()+"','"+HEADING.getText()+"','"+SECTION_ID.getSelectedItem()+"','"+SUBJECT_ID.getSelectedItem()+"','"+INSTITUTE_ID.getSelectedItem()+"','"+NEW_INSTITUTE.getText()+"','"+SENDERS_ID.getSelectedItem()+"','"+NEW_SENDER.getText()+"','"+RECEIVED_DATE.getDateFormatString()+"','"+RECEIVERS_ID.getSelectedItem()+"','"+NEW_RECEIVER.getText()+"','"+SENDING_DATE.getDateFormatString()+"')");

Related

How to change icon of label with mouse entered event?

Here is the code of mouse entered event of label 1 . And the exception is occuring .I have already worked on previous version but I don't why this happening now.
private void jLabel1MouseEntered(java.awt.event.MouseEvent evt) {
ImageIcon n_cig;
n_cig = new ImageIcon(getClass().getResource("masterproject/Cfull.png"));
jLabel1.setIcon(n_cig);
}
private void jLabel1MouseExited(java.awt.event.MouseEvent evt) {
ImageIcon n_cig;
n_cig = new ImageIcon(getClass().getResource("masterproject/No Cigarretes.png"));
jLabel1.setIcon(n_cig);
}
And the exceptions are here
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.ImageIcon.<init>(ImageIcon.java:205)
at masterproject.design.jButton1ActionPerformed(design.java:384)
at masterproject.design.access$300(design.java:15)
at masterproject.design$3.actionPerformed(design.java:148)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$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:3321)
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)
The reason that you get a NullPointerException is because for some reason the image file that you're trying to specify cannot be located. So the getResource() method returns a null.
Create a utility function to handle these kind of exception in future
public ImageIcon createImageIcon(String path,
String description) {
java.net.URL imgURL = getClass().getResource(path);
if (imgURL != null) {
return new ImageIcon(imgURL, description);
} else {
System.err.println("Couldn't find file: " + path);
return null;
}
}
Check using this function that wheather or not you are able to access the image or not

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException in Resultset

I'm Trying to run this code to get the ResultSet row by row into an Array so i can put them in a jTable. I don't get why i get this error, i'm new in this.
I would be totally thankfull if you could help me.
try {
int pos = 1;
for (int r=0;r<rsCount;r++){
String[] na = null;
res.absolute(pos);
int a=1;
while(res.next()){
na[a]=res.getString(a+1);
a+=1;
}
pos+=1;
for(int c=0;c<8;c++){
tabla.setValueAt(na[c], r, c);
}
}
} catch (SQLException ex) {
Logger.getLogger(Reporte.class.getName()).log(Level.SEVERE, null, ex);
}
}
And here is the OUTPUT:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at Main.Reporte.jButton1ActionPerformed(Reporte.java:254)
at Main.Reporte.access$000(Reporte.java:17)
at Main.Reporte$1.actionPerformed(Reporte.java:78)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$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:3321)
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:729)
at java.awt.EventQueue.access$200(EventQueue.java:103)
at java.awt.EventQueue$3.run(EventQueue.java:688)
at java.awt.EventQueue$3.run(EventQueue.java:686)
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:702)
at java.awt.EventQueue$4.run(EventQueue.java:700)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:699)
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)
Your string array is not being properly instantiated. You need to instantiate it like:
String[] na = new String[100];
If you don't know how big the array is going to be you might want to consider using an ArrayList
ArrayList<String> na = new ArrayList<String>();
then each string can be added with:
na.add(res.getString(a+1));

How can I show a JTable in a dialog box in NetBeans?

I have had a few problems trying to get this table to show in NetBeans. Here is the code that I am trying to use. I am aware that the loop is wrong and will fix that at a later date.
I get a runtime error with the following code and I can't work it out.
Object[][] data = null;
String[] columnNames = {"Type", "Grade", "Height", "Width", "Length", "Reinforced Bottom", "Reinforced Corners", "Sealable", "Quantity"};
JTable table = new JTable();
public void showTotalOrder(){
for(int i=0; i<boxes.size(); i++){
for(int j=0; j<1; j++){
data[i][j] = boxes.get(i).getName();
data[i][j+1] = boxes.get(i).getGrade();
data[i][j+2] = boxes.get(i).getHeight();
data[i][j+3] = boxes.get(i).getWidth();
data[i][j+4] = boxes.get(i).getLength();
data[i][j+5] = boxes.get(i).getReinforcedBottom();
data[i][j+6] = boxes.get(i).getReinforcedCorners();
data[i][j+7] = boxes.get(i).getSealable();
data[i][j+8] = boxes.get(i).getQuantity();
}
}
JOptionPane.showMessageDialog(this, table);
}
I believe the problem is with the last line of this method.
The error i receive is:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at coursework.FlexBox.showTotalOrder(FlexBox.java:116)
at coursework.FlexBox.currentOrderButtonActionPerformed(FlexBox.java:530)
at coursework.FlexBox.access$300(FlexBox.java:18)
at coursework.FlexBox$4.actionPerformed(FlexBox.java:435)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$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:6516)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3320)
at java.awt.Component.processEvent(Component.java:6281)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4872)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4698)
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:4698)
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)
I get a runtime error with the following code and I can't work it out.
Given this stack trace:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at coursework.FlexBox.showTotalOrder(FlexBox.java:116)
...
You get a NullPointerException because of data array is initialized to null:
Object[][] data = null;
Please have a read to:
What is a Null Pointer Exception, and how do I fix it?
Creating, Initializing, and Accessing an Array

JDBC Mysql Syntax Error

I'm using mysql and having select fields from a gui append to my query. However, I'm getting a mysql exception for this query: String query = "INSERT INTO racebikes " + "VALUES(?,?,?)";
For testing measures I printed out the query to make sure the fields were proper which when populated read as: INSERT INTO racebikes VALUES('BMC','Switzerland',10000.0). How is this throwing an syntax exception?
Stack trace:
com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '?,?,?)' at line 1
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
at com.mysql.jdbc.Util.getInstance(Util.java:386)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1054)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4237)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4169)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2617)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2778)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2828)
at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1842)
at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1764)
at JDBC_GUI$7.actionPerformed(JDBC_GUI.java:375)
at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at javax.swing.AbstractButton$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)
Snippet:
public void actionPerformed(ActionEvent e) {
String query = "INSERT INTO racebikes " + "VALUES(?,?,?)";
try{
statement = connection.prepareStatement(query);
statement.setString(1, (String)bikes_combo_box.getSelectedItem());
statement.setString(2, bike_fields[0].getText());
statement.setDouble(3, Double.parseDouble(bike_fields[1].getText()));
statement.executeUpdate(query);
} catch(SQLException e1) {
e1.printStackTrace();
}
Can you try to put the three fields before VALUES
String query = "INSERT INTO racebikes (field1, field2, field3)" + "VALUES(?,?,?)";
Replace them with your actual field names.

Jlist - ClearSelection with observer pattern

This is my first post, I'm having an issue in my application, I'm programing in Java.
I need to implement the observer pattern, because I have a main window and I need to add elements. When I add a element then the main window should be updated. I put the implements and extends Observable and Observer in the right classes and in the main window, I also override the update method. But when the update executes it throws me an exception.
Here is the code and the exeption:
#Override
public void update(Observable o, Object arg) {
// Update Hotels
this.popularHoteles(unDepartamento.getListaHoteles());
}
private void popularHoteles(ArrayList<Hotel> Hoteles) {
listaHoteles.removeAll();
if (fechasCorrectas()) {
listaHoteles.setListData(Hoteles.toArray());
}
}
where "listaHoteles" is a Jlist item on my from.
when i execute the setListDadta i recive this exeption:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at
diaztaranto.interfaces.MenuPrincipal.listaHotelesValueChanged(MenuPrincipal.java:937)
at
diaztaranto.interfaces.MenuPrincipal.access$800(MenuPrincipal.java:20)
at
diaztaranto.interfaces.MenuPrincipal$9.valueChanged(MenuPrincipal.java:345)
at javax.swing.JList.fireSelectionValueChanged(JList.java:1798) at
javax.swing.JList$ListSelectionHandler.valueChanged(JList.java:1812)
at
javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:184)
at
javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:164)
at
javax.swing.DefaultListSelectionModel.fireValueChanged(DefaultListSelectionModel.java:211)
at
javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:405)
at
javax.swing.DefaultListSelectionModel.changeSelection(DefaultListSelectionModel.java:415)
at
javax.swing.DefaultListSelectionModel.removeSelectionIntervalImpl(DefaultListSelectionModel.java:576)
at
javax.swing.DefaultListSelectionModel.clearSelection(DefaultListSelectionModel.java:420)
at javax.swing.JList.clearSelection(JList.java:2045) at
diaztaranto.interfaces.MenuPrincipal.popularHoteles(MenuPrincipal.java:998)
at
diaztaranto.interfaces.MenuPrincipal.update(MenuPrincipal.java:1043)
at java.util.Observable.notifyObservers(Observable.java:159) at
java.util.Observable.notifyObservers(Observable.java:115) at
diaztaranto.dominio.Hotel.agregarComentario(Hotel.java:212) at
diaztaranto.interfaces.Evaluacion.botonEvaluarActionPerformed(Evaluacion.java:135)
at diaztaranto.interfaces.Evaluacion.access$000(Evaluacion.java:6)
at
diaztaranto.interfaces.Evaluacion$1.actionPerformed(Evaluacion.java:56)
at
javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
at
javax.swing.AbstractButton$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:3321) 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:729) at
java.awt.EventQueue.access$200(EventQueue.java:103) at
java.awt.EventQueue$3.run(EventQueue.java:688) at
java.awt.EventQueue$3.run(EventQueue.java:686) 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:702) at
java.awt.EventQueue$4.run(EventQueue.java:700) at
java.security.AccessController.doPrivileged(Native Method) at
java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:699) 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)
any one knows why this is happen?
Thanks in advice!

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