So I am trying to make a simple chat client but somehow the connection doesn't work. Can you help me? This is what i wrote:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.net.*;
import java.util.*;
public class game implements ActionListener{
JTextArea incoming;
JTextField outgoing;
BufferedReader reader;
PrintWriter writer;
Socket sock;
public static void main(String [] args){
game g = new game();
g.go();
}public void go(){
JFrame frame = new JFrame("Chat");
JButton sendB = new JButton("Send");
JPanel mainPanel = new JPanel();
incoming = new JTextArea(15,50);
incoming.setLineWrap(true);
incoming.setWrapStyleWord(true);
incoming.setEditable(false);
JScrollPane s = new JScrollPane(incoming);
s.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
s.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
outgoing = new JTextField(25);
sendB.addActionListener(this);
mainPanel.add(s);
mainPanel.add(outgoing);
mainPanel.add(sendB);
setUpnetworking();
Thread readerThread = new Thread( new IncomingReader());
readerThread.start();
frame.getContentPane().add(BorderLayout.CENTER, mainPanel);
frame.setVisible(true);
frame.setSize(800,500);
frame.setResizable(false);
}public void actionPerformed(ActionEvent e){
try{
writer.println(outgoing.getText());
writer.flush();
}catch(Exception ex){
ex.printStackTrace();
}
outgoing.setText("");
outgoing.requestFocus();
}public void setUpnetworking(){
try {
sock = new Socket("127.0.0.1", 5000 );
InputStreamReader streamreader = new InputStreamReader(sock.getInputStream());
reader = new BufferedReader(streamreader);
writer = new PrintWriter(sock.getOutputStream());
System.out.println("Connection Established");
} catch (IOException exx) {
exx.printStackTrace();
}
}public class IncomingReader implements Runnable{
public void run(){
String message;
try{
while ((message = reader.readLine()) != null){
System.out.println("read" + message);
incoming.append(message + "\n");
}
}catch (Exception exx){exx.printStackTrace();}
}
}
}
errors i got when i ran it:
java.net.ConnectException: Connection refused: connect
at java.net.DualStackPlainSocketImpl.connect0(Native Method)
at java.net.DualStackPlainSocketImpl.socketConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.doConnect(Unknown Source)
at java.net.AbstractPlainSocketImpl.connectToAddress(Unknown Source)
at java.net.AbstractPlainSocketImpl.connect(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at java.net.Socket.<init>(Unknown Source)
at game.setUpnetworking(game.java:66)
at game.go(game.java:45)
at game.main(game.java:18)
java.lang.NullPointerException
at game$IncomingReader.run(game.java:79)
at java.lang.Thread.run(Unknown Source)
java.lang.NullPointerException
at game.actionPerformed(game.java:57)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$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)
i really don't know what's the problem :( can someone help me so i can build a working Chat Client? I use Eclipse.
Sorry for bad Englisch, I am from The Netherlands
For a chat app you need both backend and client-side solutions.
To skip the part with server-side solution development you can use a ready backend and SDK provided by some platforms. That should save you a lot of time and effort and you will be able to concentrate on UI implementation.
Here are some providers you might consider using:
ConnectyCube
Firebase
Sendbird
Layer
Here is also an article comparing features provided by some of them.
You really need to build a server. You would need to go through networking a bit. But just in case you need a server, I made one few months back. Run it separately. See if you can make it work.
https://github.com/DhavalKapil/ForwardingServer
Related
I´m trying to build an application which can read information from Excel files and place the data into a document. The document is a form of a template with columns in. Everything works just fine until the saving part.
It work, almost, like it should when I run the program directly in IntelliJ. However, when I install the application to an runnable JAR with Maven - the JAR won't work.
The file is saved as desired... But the new file contains nothing if I run the application from JAR. When i run directly in IntelliJ, the new file is been created and opened, but of 3 columns / row, only 2 has data in it.
What can I do?
Link to template document
http://www.labelmedia.de/englisch/doc/70%20x%2032%20mm%20-%20Art.%2088%2010%2027%2070%2032.doc
Thank you in advanced
package utils;
import model.Customers;
import org.apache.poi.hwpf.HWPFDocument;
import org.apache.poi.hwpf.usermodel.*;
import org.apache.poi.poifs.filesystem.POIFSFileSystem;
import java.awt.*;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
public class WriteToDocument {
String TARGET_FILE = "src\\main\\java\\utils\\template\\template.doc";
private int postInList = 0;
public WriteToDocument() {}
public WriteToDocument(ArrayList<Customers> list) throws IOException {
list.remove(0);
HWPFDocument doc = null;
try {
doc = openDocument(TARGET_FILE);
Range range = doc.getRange();
TableIterator itr = new TableIterator(range);
while (itr.hasNext()) {
Table table = itr.next();
for (int rowIndex = 0; rowIndex < table.numRows(); rowIndex++) {
TableRow row = table.getRow(rowIndex);
for (int colIndex = 0; colIndex < row.numCells(); colIndex++) {
TableCell cell = row.getCell(colIndex);
//WRITE IN TABLE //
if (postInList < list.size()) {
cell.getParagraph(0).replaceText(list.get(postInList).getName() + "\n\r" +
"\n\r" + list.get(postInList).getAddress() + "\n\r" +
list.get(postInList).getPostcode() + " " + list.get(postInList).getCity(), false);
postInList++;
}
}
}
}
} catch (Exception e) {
e.printStackTrace();
} finally {
saveDocument(doc);
}
}
private HWPFDocument openDocument(String file) throws Exception {
System.out.println("OPEN");
return new HWPFDocument(new POIFSFileSystem(new FileInputStream(file)));
}
private static void saveDocument(HWPFDocument doc) throws IOException {
System.out.println("SAVE");
try (FileOutputStream out = new FileOutputStream(new File("test.doc"))) {
doc.write(out);
out.flush();
System.out.println("File saved");
doc.close();
out.close();
Desktop dt = Desktop.getDesktop();
dt.open(new File("test.doc"));
} catch (IOException e) {
e.printStackTrace();
} finally {
}
}
Stacktrace
java.io.FileNotFoundException: src\main\java\utils\template\template.doc (Det går inte att hitta sökvägen)
at java.io.FileInputStream.open0(Native Method)
at java.io.FileInputStream.open(Unknown Source)
at java.io.FileInputStream.<init>(Unknown Source)
at java.io.FileInputStream.<init>(Unknown Source)
at utils.WriteToDocument.openDocument(WriteToDocument.java:56)
at utils.WriteToDocument.<init>(WriteToDocument.java:25)
at utils.ReadExcel.writeToDocument(ReadExcel.java:64)
at utils.ReadExcel.<init>(ReadExcel.java:57)
at MainFrameController$1.actionPerformed(MainFrameController.java:31)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$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)
SAVE
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at utils.WriteToDocument.saveDocument(WriteToDocument.java:62)
at utils.WriteToDocument.<init>(WriteToDocument.java:49)
at utils.ReadExcel.writeToDocument(ReadExcel.java:64)
at utils.ReadExcel.<init>(ReadExcel.java:57)
at MainFrameController$1.actionPerformed(MainFrameController.java:31)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$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)
Most probably you are missing libraries when it is exported as a JAR. You are using Apache POI as external libraries. Inside the IDE all the libraries were applied but when exported, they seems to be missing. Just run the jar file from command prompt to be 100% clear about the issue. In IDEs like NetBeans the libraries are exported into a separate folder called lib have a look for similar related to your IDE as well.
I created a simple table in IBM DB2 named "NAMES" with a single column "FullName" with a datatype of VARCHAR(20). I've also created a GUI with a JTextfield and JButton to add data into the table through GUI. When the button is clicked, the text in the textfield will be inserted into the table NAMES. But there's an error when I click the button.
Here is the java code.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.sql.*;
public class FirstClass extends JFrame implements ActionListener
{
private Connection connection;
private JTextField fieldTF;
private JButton addB;
public FirstClass() throws SQLException , ClassNotFoundException
{
setDefaultCloseOperation(this.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
fieldTF = new JTextField(20);
addB = new JButton("Add");
Container cont = this.getContentPane();
cont.setLayout(new FlowLayout());
cont.add(fieldTF);
cont.add(addB);
setConnection();
addB.addActionListener(this);
pack();
validate();
setVisible(true);
}
public void setConnection() throws SQLException , ClassNotFoundException
{
Class.forName("com.ibm.db2.jcc.DB2Driver");
connection = DriverManager.getConnection("jdbc:db2://localhost:50000/COLINN","Colinn","ezioauditore");
System.out.print("Connected Succesfully");
}
public void write(String name) throws SQLException , ClassNotFoundException
{
PreparedStatement statement = null;
String query = null;
query = "INSERT INTO NAMES VALUES (?)";
statement.setString(1,name);
statement.executeUpdate();
}
public void actionPerformed(ActionEvent e)
{
try
{
write(fieldTF.getText());
}catch(Exception ex)
{
ex.printStackTrace();
}
}
public static void main(String args[]) throws SQLException , ClassNotFoundException
{
new FirstClass();
}
}
Here is the error:
java.lang.NullPointerException
at FirstYearProject.FirstClass.write(FirstClass.java:49)
at FirstYearProject.FirstClass.actionPerformed(FirstClass.java:58)
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)
I've already imported External Jars from DB2 to establish connection with Java. I think there's a problem with the query or problem in executing it.
There's a problem here:
PreparedStatement statement = null; // **** set to null here
String query = null;
query = "INSERT INTO NAMES VALUES (?)";
statement.setString(1,name); // **** use it here!
Where does statement become non-null before you use it?
You need to key in on line 49 and 58 of the FirstClass.java class as per the exception stacktrace message, FirstClass.java:49.
Also, you will want to learn the general concepts of how to debug a NPE (NullPointerException). You should critically read your exception's stacktrace to find the line of code at fault, the line that throws the exception, and then inspect that line carefully, find out which variable is null, and then trace back into your code to see why. You will run into these again and again, trust me.
So here:
java.lang.NullPointerException
at FirstYearProject.FirstClass.write(FirstClass.java:49)
at FirstYearProject.FirstClass.actionPerformed(FirstClass.java:58)
The stacktrace tells you to carefully inspect lines 49 and 58.
Note, you need to create a PreparedStatement object before you try to use it. First you'd create a Connection, and then you'd use that Connection to create the PreparedStatement via Connection's preparedStatement(...) method. This is all well described in the Java JDBC Tutorials. Pay particular attention to the PreparedStatement subsection.
I want to serialize and save an arraylist that contains a double [] arraylist in java. Here is my code.
FileOutputStream fileOutputStream = null;
ObjectOutputStream objectOutputStream = null;
FileInputStream fileInputStream = null;
ObjectInputStream objectInputStream = null;
public void writeArrayListToFile(ArrayList<ArrayList<double []>> arraylist, String outputFilePath){
System.out.println("Start saving the file at : " + outputFilePath);
try {
fileOutputStream = new FileOutputStream(outputFilePath , true);
objectOutputStream = new ObjectOutputStream(objectOutputStream);
objectOutputStream.writeObject(arraylist);
System.out.println("Arraylist Saved Successfully...");
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
But I get an error and following is the stack trace.
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at java.io.ObjectOutputStream$BlockDataOutputStream.drain(Unknown Source)
at java.io.ObjectOutputStream$BlockDataOutputStream.setBlockDataMode(Unknown Source)
at java.io.ObjectOutputStream.(Unknown Source)
at com.fyp.imur2.SaveArrayListToFile.writeArrayListToFile(SaveArrayListToFile.java:24)
at com.fyp.imur2.JPanelJFreeChart.btnSaveGestureCollectionActionPerformed(JPanelJFreeChart.java:380)
at com.fyp.imur2.JPanelJFreeChart.access$5(JPanelJFreeChart.java:375)
at com.fyp.imur2.JPanelJFreeChart$6.actionPerformed(JPanelJFreeChart.java:166)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$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$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)
Can someone help me to solve this issue? Any help would be appreciated. Thanks in advance.
Need to pass fileOutputStream while constructing the instance of ObjectOutputStream
objectOutputStream = new ObjectOutputStream(fileOutputStream);
on the line
objectOutputStream = new ObjectOutputStream(objectOutputStream);
You try to call the constructor with the objectOutputStream object, which is null. Looks like you meant to call it with fileOutputStream, like this:
objectOutputStream = new ObjectOutputStream(fileOutputStream);
i found a java file on the web that allows me to read a pdf in a url and save it to my local machine,
i have sucsesfully compiled it and customized as a javabean so i can useit in my app, but when i test it i am getting the next error message.
i have added the library (PDFOne.jar file) to my project in netbean and averything compiles well.
in fact, the program detect my pdf url and validate it saying is a valid pdf file, but then the error comes:
any tip ? i am completely new in java world.
thanks in advance
Exception in thread "AWT-EventQueue-2" java.lang.NoClassDefFoundError: com/gnostice/pdfone/PdfDocument
at Read_PDF_From_URL.setProperty(Read_PDF_From_URL.java:51)
at oracle.forms.handler.ComponentItem.setCustomProperty(Unknown Source)
at oracle.forms.handler.ComponentItem.onUpdate(Unknown Source)
at oracle.forms.handler.JavaContainer.onUpdate(Unknown Source)
at oracle.forms.handler.UICommon.onUpdate(Unknown Source)
at oracle.forms.engine.Runform.onUpdateHandler(Unknown Source)
at oracle.forms.engine.Runform.processMessage(Unknown Source)
at oracle.forms.engine.Runform.processSet(Unknown Source)
at oracle.forms.engine.Runform.onMessageReal(Unknown Source)
at oracle.forms.engine.Runform.onMessage(Unknown Source)
at oracle.forms.engine.Runform.processEventEnd(Unknown Source)
at oracle.ewt.lwAWT.LWComponent.redispatchEvent(Unknown Source)
at oracle.ewt.lwAWT.LWComponent.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$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)
Caused by: java.lang.ClassNotFoundException: com.gnostice.pdfone.PdfDocument
at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 39 more
here is part of the source code:
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ConnectException;
import java.net.URL;
import java.net.URLConnection;
import oracle.forms.properties.*;
import oracle.forms.ui.*;
import com.gnostice.pdfone.PdfDocument;
import java.net.MalformedURLException;
public class Read_PDF_From_URL extends VTextArea {
private static final ID GEN = ID.registerProperty("sav");
public boolean setProperty(ID id, Object value) {
boolean retorno = true;
try {
if (id == GEN) {
System.out.println("if");
URL url1 =
new URL("http://www.gnostice.com/downloads/Gnostice_PathQuest.pdf");
byte[] ba1 = new byte[1024];
int baLength;
FileOutputStream fos1 = new FileOutputStream("sibdownload.pdf");
// Contacting the URL
System.out.print("Connecting to " + url1.toString() + " ... ");
URLConnection urlConn = url1.openConnection();
// Checking whether the URL contains a PDF
if (!urlConn.getContentType().equalsIgnoreCase("application/pdf")) {
System.out.println("FAILED.\n[Sorry. This is not a PDF.]");
} else {
try {
// Read the PDF from the URL and save to a local file
InputStream is1 = url1.openStream();
while ((baLength = is1.read(ba1)) != -1) {
fos1.write(ba1, 0, baLength);
}
fos1.flush();
fos1.close();
is1.close();
// Load the PDF document and display its page count
System.out.print("DONE.\nProcessing the PDF ... ");
PdfDocument doc = new PdfDocument();
try {
doc.load("sibdownload.pdf");
System.out.println("DONE.\nNumber of pages in the PDF is " +
I have resolved my question... The first thing was that I've needed to include the jar file in my classpath and the second thing that I've needed to sign the jar file.
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.