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Java sqlite database is locked

I am trying to delete a student from database, but I got this error:
java.sql.SQLException: database is locked
at org.sqlite.core.DB.throwex(DB.java:859)
at org.sqlite.core.DB.exec(DB.java:142)
at org.sqlite.jdbc3.JDBC3Connection.commit(JDBC3Connection.java:165)
at Controller.deleteStudent(Controller.java:232)
at Test$9.actionPerformed(Test.java:227)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$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)
I read other posts on stackoverflow and all of them said that all connections needs to be closed to open a new connection. I did this, but I still got the same problem.
Here's my code:
public static void deleteStudent(int id) {
try {
con = null;
Class.forName("org.sqlite.JDBC");
con = DriverManager.getConnection("jdbc:sqlite:test.db");
con.setAutoCommit(false);
stmt = null;
stmt = con.createStatement();
int result = stmt.executeUpdate("DELETE FROM STUDENTS WHERE ID=" + id + ";");
System.out.println(result);
con.commit();
stmt.close();
con.close();
output();
} catch (ClassNotFoundException | SQLException e) {
e.printStackTrace();
}
}
Do you have ideas why I still get this error?

NullPointerException when calling getSelectedItem() on an editable JComboBox

I have an editable combo box with a key listener. I want to write some text in it and with every letter, it has to make a string with the text I have inserted (or deleted).
But when I want to get the string I get a NullPointerException.
combobox.getEditor().getEditorComponent()
.addKeyListener(new KeyListener()
{
String value="";
#Override
public void keyTyped(KeyEvent e)
{
value = combobox.getSelectedItem().toString();
System.out.println(value);
}
#Override
public void keyReleased(KeyEvent e)
{
}
#Override
public void keyPressed(KeyEvent e)
{
}
});
Stack trace:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at auftrag_paket.Neuer_Auftrag_ohneMwSt$25.keyTyped(Neuer_Auftrag_ohneMwSt.java:2037)
at java.awt.Component.processKeyEvent(Unknown Source)
at javax.swing.JComponent.processKeyEvent(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.KeyboardFocusManager.redispatchEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(Unknown Source)
at java.awt.DefaultKeyboardFocusManager.dispatchEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(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$400(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$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.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$1.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.pumpEventsForFilter(Unknown Source)
at java.awt.WaitDispatchSupport$2.run(Unknown Source)
at java.awt.WaitDispatchSupport$4.run(Unknown Source)
at java.awt.WaitDispatchSupport$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.awt.WaitDispatchSupport.enter(Unknown Source)
at java.awt.Dialog.show(Unknown Source)
at java.awt.Component.show(Unknown Source)
at java.awt.Component.setVisible(Unknown Source)
at java.awt.Window.setVisible(Unknown Source)
at java.awt.Dialog.setVisible(Unknown Source)
at auftrag_paket.Auftragsverwaltung$14.actionPerformed(Auftragsverwaltung.java:1865)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$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$400(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$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.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$1.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)
Has anyone any ideas?

Don't use a KeyListener that is old code when using AWT. Swing has newer and better API's.
Instead you should be using a DocumentListener. Read the section from the Swing tutorial on How to Write a Document Listener for more information.

To capture any character typed in combobox using KeyListener, you should do it inside keyReleased method, try the following code:
combobox.getEditor().getEditorComponent()
.addKeyListener(new KeyListener()
{
String value="";
#Override
public void keyTyped(KeyEvent e)
{
}
#Override
public void keyReleased(KeyEvent e)
{
value = combo.getSelectedItem().toString();
value = ((JTextField)combo.getEditor().getEditorComponent()).getText();
System.out.println(value);
}
#Override
public void keyPressed(KeyEvent e)
{
}
});

Opening a file produces a java.lang.NullPointerException

I have a JFrame and on the frame I have JButton, what I want is when that file is clicked that the user can load a file using the java JFileChooser.
I declare the FileChooser like this.
JFileChooser fc;
And then here is my code in the action listener for the button.
JButton btnLoad = new JButton("Load .txt");
btnLoad.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int returnVal = fc.showOpenDialog(OpenFile.this);
if (returnVal == JFileChooser.APPROVE_OPTION) {
File file = fc.getSelectedFile();
//This is where a real application would open the file.
System.out.println("Opening: " + file.getName() + ".");
} else {
System.out.println("Open command cancelled by user.");
}
}
});
The error that it is producing me is
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at maple.Netflix$2.actionPerformed(Netflix.java:73)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$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.AWTEventMulticaster.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$200(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$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.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$1.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)
Here is line 73.
int returnVal = fc.showOpenDialog(Netflix.this);

Just declaring the JFileChooser variable is not enough, as you need to initialize the reference variable, fc, to a valid object first before using it. This is the same as for any other reference variable.
JFileChooser fc = new JFileChooser();

The value of fc is null. It needs to be set to that of an appropriate object before you call methods on it.

NullPointerException when try to capture imagem from webcam

I got an error in my line 508 where I have this code
buf = fgc.grabFrame();
CODE:
startC.addActionListener(new ActionListener()
{
#Override
public void actionPerformed(ActionEvent e)
{
// Grab a frame
FrameGrabbingControl fgc = (FrameGrabbingControl)
player.getControl("javax.media.control.FrameGrabbingControl");
buf = fgc.grabFrame();
// Convert it to an image
BufferToImage btoi = new BufferToImage((VideoFormat)buf.getFormat());
img = btoi.createImage(buf);
// show the image
//imgpanel.setImage(img);
// save image
try {
saveJPG(img,"c:\\test.jpg");
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}):
STACK:
Exception in thread "AWT-EventQueue-1" java.lang.NullPointerException
at com.colorfulwolf.webcamapplet.WebcamApplet$6.actionPerformed(WebcamApplet.java:508)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$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.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(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$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.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$1.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)
What's going wrong with this line ?

You need to assign player to an instance:
public static Player player = new Player();

Getting "java.lang.ArrayIndexOutOfBoundsException" while reading ".doc" files using Apache POI API

Here is the exception I am getting:
Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 20203
at org.apache.poi.util.LittleEndian.getShort(LittleEndian.java:45)
at org.apache.poi.hwpf.model.ListLevel.(ListLevel.java:120)
at org.apache.poi.hwpf.model.ListFormatOverrideLevel.(ListFormatOverrideLevel.java:48)
at org.apache.poi.hwpf.model.ListTables.(ListTables.java:88)
at org.apache.poi.hwpf.HWPFDocument.(HWPFDocument.java:267)
at org.apache.poi.hwpf.HWPFDocument.(HWPFDocument.java:157)
at com.mahesh.MyFrame.readMSDocuments(MyFrame.java:301)
at com.mahesh.MyFrame.readALLDocuments(MyFrame.java:276)
at com.mahesh.MyFrame.access$1(MyFrame.java:269)
at com.mahesh.MyFrame$2.actionPerformed(MyFrame.java:231)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$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.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)
And this is my code
private void readMSDocuments(String fileToRead) {
boolean containsEditorAndMt = false;
String fileEditorAndMt = null;
dataArray = null;
try {
fis = new FileInputStream(new File(fileToRead).getAbsolutePath());
fs = new POIFSFileSystem(fis);
document = new HWPFDocument(fs);
wordExtractor = new WordExtractor(document);
dataList = new ArrayList();
dataArray = wordExtractor.getParagraphText();//getParagraphText() reads paragraphs so problem is each paragraph is read a single line .u can see in console
System.out.println(dataArray.length);
if (dataArray.length >= 0) {
for (int k = 0; k < dataArray.length; ++k) {
if (dataArray[k].trim().length() > 0) {
dataList.add(dataArray[k].trim());
//System.out.println(fileToRead+" "+dataArray[k].trim()+"\n");
}
}
}
}
}
Could anyone help me find out why the exception is thrown?

You are using Apachi POI API:
This is a bug in this domain.
You can read about this bug and analyze through this.