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I'm working on a servelet project. I use database connection (jdbc odbc) when I try to access data into database, I get HTTP status 500 error
java.lang.NullPointerException
checkpps.doGet(checkpps.java:61)
javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
line 61 in my code is : statement = link.createStatement();
any body could help me please???
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At the risk of stating the obvious, link is null. More than that I cannot say, because I don't know what link is or how you get hold of it.
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import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class checkpps extends HttpServlet{
private Statement statement;
private Connection link;
private String URL = "jdbc:odbc:quiz";
String name;
public void init() throws ServletException
{
super.init();
try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
link = DriverManager.getConnection("jdbc:odbc:quiz","sara", "sara");
}
catch (ClassNotFoundException e1){
System.out.println("driver not found");
}
catch (SQLException e2){
System.out.println("error in connection");
}
}
public void doGet ( HttpServletRequest req,
HttpServletResponse res) throws ServletException, IOException {
res.setContentType ("text/html");
PrintWriter out= res.getWriter();
String city = req.getParameter("city");
String ppsnum = req.getParameter("ppsno");
try {
statement = link.createStatement();
ResultSet result = statement.executeQuery("SELECT * FROM player");
while(result.next())
{
out.println("<p>" + result.getString("ppsno"));
}
}
catch (SQLException e)
{
System.out.println("error statement");
}
}
public void destroy()
{
try {
link.close();
}
catch (Exception e) {
System.out.println("error on closing!!");
e.printStackTrace();
System.exit(1);
}
}
}
as you see in my code, I'm trying to connect to database (MS Access) and link is my connection name. seems my connection has problem for some reason but still couldn't solve it. I have created DSN by the way.
any help?
modified on Wednesday, November 11, 2009 8:51 AM
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Which MSOffice you are using. And r you sure that you have selected the correct driver type.
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Hey Everyone
I am learning Java and would like to know how to get started on writing a piece of code that takes a collection of objects (which are answers from a form) and save it in a file (xml or .txt)
the FORM can be design from any visual editor (Flex, SWING, HTML, JSP etc...)
but once the form has been filled out, I want to save all the answers in a xml or .txt file
Any help would be greatly appreciated
thanks
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public void saveAnswers()
{
try
{
FileWriter fw = new FileWriter("Questions.txt");
PrintWriter pw = new PrintWriter(fw);
pw.println(textBox1.getText());
pw.println(textBox2.getText());
pw.println(textBox3.getText());
pw.println(textBox4.getText());
pw.flush();
}
}catch(Exception e)
{
System.out.println(e);
}
}
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Hi all,
Actually, i have developed a java application that connects with Ms Access database. now i want to deploy this application. is there a way i can bundle my database inside the jar. if not please suggest some appropriate way ( a step by step procedure)
thanx
regards
Adeel
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Is there a Java validator out there that can validate against the proposed W3C XSD v1.1 specification? I am currently validating against an XSD v1.0, but would like to add a number of assert statements and conditional attributes. If it helps, my current validation against XSD v1.0 is performed as follows (assume xsdFullPath and xmlFullPath are already defined):
parserFactory = javax.xml.parsers.DocumentBuilderFactory.newInstance();
parserFactory.setNamespaceAware(true);
parserFactory.setXIncludeAware( true);
parserFactory.setFeature('http://apache.org/xml/features/xinclude/fixup-base-uris',false);
parserFactory.setFeature('http://apache.org/xml/features/xinclude/fixup-language' ,false);
parser = parserFactory.newDocumentBuilder();
parser.setErrorHandler(org.xml.sax.helpers.DefaultHandler());
document = parser.parse(xmlFullPath);
xmldom = javax.xml.transform.dom.DOMSource(document);
factory = javax.xml.validation.SchemaFactory.newInstance(...
javax.xml.XMLConstants.W3C_XML_SCHEMA_NS_URI);
schemaFile = javax.xml.transform.stream.StreamSource(xsdFullPath);
schema = factory.newSchema(schemaFile);
validator = schema.newValidator();
validator.validate(xmldom);Thanks,
Sounds like somebody's got a case of the Mondays
-Jeff
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I have a simple question, I developed a java application, which runs on Oracle application server and Oracle database. This application depends on multiple JSPs on which multiple users can access a single JSP in the same time, some problems occurs due to the excessive usage of this application and I have some questions about them:
1. Is there any danger or disadvantages in connecting to the database using the jdbc directly from the JSP ?!!
2. An error occurs almost once a week (most probably at the point of time when an excessive usage happens). This error stops the users from submitting or accessing the some JSPs. I ran the following query on the DB to find any locked items:
SELECT o.owner, o.object_name, o.object_type, o.last_ddl_time, o.status,l.session_id, l.oracle_username, l.locked_mode
FROM dba_objects o, gv$locked_object l
WHERE o.object_id = l.object_id;
I found that the table I use to select from in the halted JSPs is a result of this query.
In order to solve this problem temporarily, i use the sql developer to add a record to this table and commit, i find that the problem is solved and the halted jsps involved are running.
These are the exceptions that appears in the log files of the application server right after I press commit:
a.java.lang.IllegalStateException: Session was invalidated (all the time)
b.java.sql.SQLException: Closed Connection (some times)
I do not know exactly where to start debugging, since i use synchronization in all of my code. Also I made sure that each user accessing the same JSP has a separate connection.
Thanks in advance
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Errors im getting:
cannot find symbol constructor method Token. but i do have a constructor in Token class
cannot find symbol variable tokenCode. i clearly use it alll over and i think i initialized it properly so whats wrong?
cannot find symbol variable scantest.i have that in same folder where all classes are in why wont it read it?
scanner class in which i need help fixing the above errors
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.*;
public class scanner implements CompilerConstants {
private char c;
private BufferedReader source;
public int token;
private String attr = "";
private
public scanner(BufferedReader buffer) {
source = buffer;
getChar();
}
public void getChar()
{
c = (char)(source.read());
}
public boolean lookup(String word)
{
boolean check = false;
for(int i=0; i < RESERVEDWORD.length;i++)
if(word==(RESERVEDWORD[i]))
{
check = true;
}
return check;
}
public Token nextToken() throws IOException
{
attr = "";
while(c!=EOFCHAR);
{
while (Character.isWhitespace(c))
{
getChar();
}
if (Character.isLetter(c))
{
while(Character.isLetterOrDigit(c))
{
attr = attr + c;
getChar();
}
return new Token(lookup(attr), attr);
}
else if (Character.isDigit(c)) {
while(Character.isDigit(c))
{
attr = attr + c;
getChar();
}
return new Token(NUMBER, attr);
}
else {
switch (c) {
case '<' : getChar();
if(c=='>')
{
getChar();
return new Token(NE, null);
}
else if (c=='=')
{
getChar();
return new Token(LE, null);
}
return new Token(LT, null);
case '>' : getChar();
if(c=='<')
{
getChar();
return new Token(NE, null);
}
else if (c=='=')
{
getChar();
return new Token(GE, null);
}
return new Token(GT, null);
case '=' : getChar();
return new Token(EQ, null);
case '|' : getChar();
return new Token(OR, null);
case '+' : getChar();
return new Token(PLUS, null);
case '-' : getChar();
return new Token(MINUS, null);
case '*' : getChar();
return new Token(TIMES, null);
case '/' : getChar();
return new Token(DIVIDE, null);
case '[' : getChar();
return new Token(LEFTSQ, null);
case ']' : getChar();
return new Token(RIGHTSQ, null);
case '(' : getChar();
return new Token(LEFTPAREN, null);
case ')' : getChar();
return new Token(RIGHTPAREN, null);
case ',' : getChar();
return new Token(COMMA, null);
case EOFCHAR : getChar();
return new Token(EOF, null);
}
}
return Token(tokenCode, attr);
}
}
public static void main(String[] args)
{
BufferedReader source = new BufferedReader(new FileReader(scantest.echo));
}
}
Token class
public class Token implements CompilerConstants {
private int tokenCode;
private String attribute;
public Token(int tc, String att)
{
tokenCode = tc;
attribute = att;
}
public int getToken()
{
return tokenCode;
}
public String tokenAttribute()
{
return attribute;
}
public String toString(){
String tokenString = tokenCode + " ";
switch (tokenCode) { case AND: return (tokenString + "/n AND");
case IDENTIFIER: return (tokenString + "/n IDENTIFIER" + attribute);
case OR: return (tokenString + "/n OR");
case NOT: return (tokenString + "/n NOT");
case ARRAY: return (tokenString + "/n ARRAY");
case BEGIN: return (tokenString + "/n BEGIN ");
case BOOLEAN: return (tokenString + "/n BOOLEAN ");
case DO: return (tokenString + "/n DO ");
case ELSE: return (tokenString + "/n ELSE");
case END: return (tokenString + "/n END");
case FOR: return (tokenString + "/n FOR");
case FROM: return (tokenString + "/n FROM");
case IF: return (tokenString + "/n IF");
case INTEGER: return (tokenString + "/n INTEGER");
case PROCEDURE: return (tokenString + "/n PROCEDURE");
case PROGRAM: return (tokenString + "/n PROGAM");
case READ: return (tokenString + "/n READ");
case START: return (tokenString + "/n START");
case THEN: return (tokenString + "/n THEN");
case TO: return (tokenString + "/n TO");
case TRUE: return (tokenString + "/n TRUE");
case WHILE: return (tokenString + "/n WHILE");
case WRITE: return (tokenString + "/n WRITE");
case WRITELN: return (tokenString + "/n WRITELN");
case NUMBER: return (tokenString + "/n NUMBER" + attribute);
case STRING: return (tokenString + "/n STRING" + attribute);
case LT: return (tokenString + "/n LT");
case LE: return (tokenString + "/n LE");
case GT: return (tokenString + "/n GT");
case GE: return (tokenString + "/n GE");
case EQ: return (tokenString + "/n EQ");
case NE: return (tokenString + "/n NE");
case PLUS: return (tokenString + "/n PLUS");
case MINUS: return (tokenString + "/n MINUS");
case TIMES: return (tokenString + "/n TIMES");
case DIVIDE: return (tokenString + "/n DIVIDE");
case LEFTSQ: return (tokenString + "/n LEFTSQ");
case RIGHTSQ: return (tokenString + "/n RIGHTSQ");
case LEFTPAREN: return (tokenString + "/n LEFTPAREN");
case COLONEQUAL: return (tokenString + "/n COLONEQUAL");
case COMMA: return (tokenString + "/n COMMA");
case EOF: return (tokenString + "/n EOF");
}
return tokenString;
}
}
CompilerConstants class
public interface CompilerConstants {
public static final int AND = 1;
public static final int ARRAY = 2;
public static final int BEGIN = 3;
public static final int BOOLEAN = 4;
public static final int DO = 5;
public static final int ELSE = 6;
public static final int END = 7;
public static final int FALSE = 8;
public static final int FOR = 9;
public static final int FROM = 10;
public static final int IF = 11;
public static final int INTEGER = 12;
public static final int NOT = 13;
public static final int OR = 14;
public static final int PROCEDURE = 15;
public static final int PROGRAM = 16;
public static final int READ = 17;
public static final int START = 18;
public static final int THEN = 19;
public static final int TO = 20;
public static final int TRUE = 21;
public static final int WHILE = 22;
public static final int WRITE = 23;
public static final int WRITELN = 24;
public static final int IDENTIFIER = 30;
public static final int NUMBER = 31;
public static final int STRING = 32;
public static final int LT = 33;
public static final int LE = 34;
public static final int GT = 35;
public static final int GE = 36;
public static final int EQ = 37;
public static final int NE = 38;
public static final int PLUS = 39;
public static final int MINUS = 40;
public static final int TIMES = 41;
public static final int DIVIDE = 42;
public static final int LEFTSQ = 43;
public static final int RIGHTSQ = 44;
public static final int LEFTPAREN = 45;
public static final int RIGHTPAREN = 46;
public static final int COLONEQUAL = 47;
public static final int COMMA = 48;
public static final int EOF = 99;
public static final char EOFCHAR = (char)(-1);
public static final String[] RESERVEDWORD = {"","and","array","begin","boolean",
"do","else","end","false","for","from","if","integer","not","or",
"procedure","program","read","start","then","to","true","while",
"write","writeln"};
public static final boolean DEBUG = true;
}
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Here goes error by error:
symbol : constructor Token(boolean,java.lang.String)
location: class Token
return new Token(lookup(attr), attr);
The constructor for Token has the signature Token(int, java.lang.String). Your code for lookup returns a boolean.
symbol : variable tokenCode
location: class scanner
return Token(tokenCode, attr);
It's amazing that a private member variable from a different class is inaccessable. Yes, tokenCode is never declared in the class scanner. BTW it would be better to rename the class to Scanner; naming conventions and all that.
symbol : variable scantest
location: class scanner
BufferedReader source = new BufferedReader(new FileReader(scantest.echo));
What is scantest? If it should be a variable declare it, if it's a static class then it doesn't appear to be a part of the project.
I found all your errors just by reading the post, I didn't compile it. Subsequently I copied into a netbean project and built to check I was right. Which I am.
Panic, Chaos, Destruction.
My work here is done.
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Thanks i fixed my errors. Do you know how it would be a good way to start a parser class that will work with my code?
This is what i have so far
public class Parser implements Scanner {
public Parser() {
}
public int match(expectedToken)
{
if(Token = expectedToken)
{
nextToken()
}
else if(Token != expectedToken)
{
}
break;
}
public static void type() throws IOException
{
debugStart(type);
simpleType();
if(Token, tokenCode==ARRAY)
{
match(ARRAY);
match (LEFTSQ);
match (RIGHTSQ);
match(NUMBER);
}
debugEnd(type);
}
}
modified on Tuesday, November 10, 2009 3:58 PM
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import java.util.Random;
/**
* Write a description of class PokerHand here.
*
* @author David Singleton
* @version 11/08/09
*/
public class PokerHand
{
public PokerHand()
{
this.arrDeck = new int[5];
// this.hand = new int[5];
//
}
// private ArrayList<string> coins;
public static void main(String[] args)
{
}
public boolean haveCard(int cardValue)
{
// Visit each array box and compare card to the number in the box
// If the card martches the array box value then return true
// If the card does not match any array values in the entire array then
// return false.
// Use a while loop to visit each array box
if(arrDeck.length > 0)
{
for (int i=0; i < this.arrDeck.length; ++i)
{
if (this.arrDeck[i] == cardValue)
{
return true;
}
return false;
}
}
public void displayCards()
{
System.out.println("The Card Values Are: ");
for(int i=0; i<=arrDeck.length; i++)
{
System.out.println(arrDeck[i] +"/n");
}
}
public void dealCards(boolean inHand)
{
// syntax error "illegal start of expression"
// public int randomPokerCard()
Random randomGenerator = new Random();
int randomInt = 0;
for(int i = 0; i
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sweetbab wrote: PokerHand class can someone help me solve this code?
Solve what exactly? You need to explain what this is supposed to do, and what errors are occurring.
[edit]I notice that main() does not actually do anything!
The variable arrDeck is not declared anywhere.
The statement for(int i = 0; i { has obviously been pasted incorrectly, so I'm not sure what the test or termination parts should be.
I would suggest you correct these errors and repost your question with some more detail.
[/edit]
modified on Sunday, November 8, 2009 7:14 AM
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Hi everybody,
I am doing an application using java.It requires a module to send sms to people concerned. So kindly give or help me with the algorithm or coding to send sms from computer.
Thank you.
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Implementing this should be easier Youtube[^]. Before you ask how to send an email look in this forum you will find the answer.
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this is the code i have. when i run this applet, it doesn't do anything!
[quote]
//Ravi Shah
//Assignment 7: Java applet for a small airline company
//to make reservations.
//CIS 226
//11/05/09
import java.awt.Container;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class Air_Reservation extends JApplet implements ActionListener
{
boolean seats[];
JButton FirstClassButton;
JButton EconomyButton;
JTextField BoardingPassField;
public Air_Reservation()
{
seats = new boolean[1];
}
public void init()
{
Container container = getContentPane();
container.setLayout(new FlowLayout());
FirstClassButton = new JButton("First Class");
FirstClassButton.addActionListener(this);
container.add(FirstClassButton);
EconomyButton = new JButton("Economy");
EconomyButton.addActionListener(this);
container.add(EconomyButton);
BoardingPassField = new JTextField(20);
BoardingPassField.setEditable(false);
container.add(BoardingPassField);
}
public void actionPerformed1(ActionEvent actionEvent)
{
boolean FirstClass = actionEvent.getSource() == FirstClassButton;
int seat = 0;
if(seat == -1 )
{
String ok = JOptionPane.showInputDialog(null, (new StringBuilder("Are you OK with ")).append(FirstClass ? "Economy" : "FirstClass").append(" (click OK or Cancel)").toString());
if(ok != null)
{
FirstClass = !FirstClass;
}
}
if(seat > 0)
{
BoardingPassField.setText((new StringBuilder("Boarding Pass: Seat ")).append(seats).append(FirstClass ? " FirstClass" : " Economy").toString());
} else
if(seat < -1)
{
BoardingPassField.setText("Next flight leaves in 3 hours");
} else
{
BoardingPassField.setText("All the seats have been reserved");
EconomyButton.setEnabled(false);
}
}
public int reserve(boolean firstClass)
{
int start = 1;
int end = 5;
boolean full = false;
if(firstClass)
{
start = 6;
end = 10;
}
for(int i = 1; i <= 10; i++)
{
if(i >= start && i <= end)
{
seats[i] = true;
return i;
}
}
return end;
}
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
}
}
[/quote]
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Programmers are really amazing!
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I think you are in the wrong place 
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Shah Ravi wrote: this is the code i have. when i run this applet, it doesn't do anything!
What is it supposed to do?
ps Please use <pre></pre> tags around your code; there is even a "code block" button on the edit screen to make it easy for you!
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By looking at your code I can directly tell you to delete the last method (actionPerformed) and also to remove the 1 from the first (actionPerformed).But now your stuck with when you click either button you will get the same result. There are many ways to add action listeners and the way your doing it is wrong. A nice link [^]to explain it all.
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Hi all. I am creating an ant script for a JEE project and when compiling the webservices of that project I get the following error java.lang.IncompatibleClassChangeError: Class com.sun.tools.javadoc.ClassDocImpl does not implement the requested interface com.sun.javadoc.Type
I decompiled the code of tools.jar and found that the interface is implemented but can't find out how to get rid of this error. Has anyone seen it before. I am working on oracle workshop with java 6 and I'm out of ideas about this. If anybody can help I would hold it in heig regard.
Cheers
Stephen
Stephen Lintott Bsc IT (RAU)
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I found this advice:
Every time I have seen this kind of error it was because I changed a class that
other classes depended on, but did not recompile the dependent classes. Be sure
that you completely delete all the old *.class files of your application, and
recompile them against the new struts.jar file.
So I'd make sure you do a clean build and make sure you are linking to the correct jars. Is it possible you have two jdk's installed and you are getting the jars from different versions?
Panic, Chaos, Destruction.
My work here is done.
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Thanks Nagy...
The only thing is I'm not working with struts. These are webservices that allow the user to access control objects written by our company. All and all we have 11 projects ie 11 build.xml files for ears. 5 of them complile and 6 of them fail with the above error when they are run via a bash script that I wrote. I thought of it after the first post but does anyone know if weblogic replaces the tools.jar file when compiling. Maby named it something else. I'm not even sure if you are allowed to do that. Anyway. if anybody can help I would hold it in very high regard...
Cheers
Stephen
Stephen Lintott Bsc IT (RAU)
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Hi to all,this is my first post...
I've built a java program which retrive some datas from a website and organize them in a JTable... nothing too complicated
The "bigger" problem was that I need to make it start at system startup (it's a desktop application for some users)
I build a dll with JNI and created some functions to interact with registry, after that was easy to write on the system register and yes I managed to run the application at system startup.
Actually I'm using a wrapper for my jar files called "launch4j", which simply call my jar file (I don't need to wrap or something like it... just the users are more "user-friendly" with an exe file instead of a jar (I don't need a JVM check because i'm doing it at installation time, with another tool)...
However, the exe is called but I got these errors
Problemi nella creazione della GUI: null
java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Unknown Source)
at java.lang.Integer.<init>(Unknown Source)
at gui.Home.<init>(Home.java:52)
at cittanascostauc.Main$1.run(Main.java:22)
at java.awt.event.InvocationEvent.dispatch(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 if I disable the part of that integer (the problem is that is read from a file, so the problem is the file reading and not exactly the cast), so I have only the part referred to the DLL I receive this error:
Exception in thread "AWT-EventQueue-0" java.lang.UnsatisfiedLinkError: no AutoSt
artChecker in java.library.path
at java.lang.ClassLoader.loadLibrary(Unknown Source)
at java.lang.Runtime.loadLibrary0(Unknown Source)
at java.lang.System.loadLibrary(Unknown Source)
at core.AutoStartChecker.<clinit>(AutoStartChecker.java:35)
at gui.Home.<init>(Home.java:72)
at cittanascostauc.Main$1.run(Main.java:22)
at java.awt.event.InvocationEvent.dispatch(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)
Actually if I manually run the exe file, everything goes fine... it's something like no dll are loaded... In fact if I disable everything about File reading and DLL Management, the GUI comes up and everything works fine (even if the user call some operations which read/write on file)
How can I resolve this problem?any suggestion?
EDIT: New discover!
I've build this batch file:
cd "C:\Documents and Settings\Administrator\Desktop"
MyWrapperForApp.exe
If I run this on system startup everything works... (yes that's not what I want) I've understood why this happen: it looks like that when I run my jar app at startup, the "dir" where it's run from it's not (currently is on my desktop) the desktop, but somewhere else (probably C:\WINDOWS\system32 ?Or where the jre is, more probably). So actually my jar file starts (infact I "arrive" inside my main function) and then I got some bugs... The solution could be simply changing the current working dir of my jar file, do someone know how to do this? It will be very appreciated a help
modified on Monday, November 2, 2009 9:33 PM
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