Help me! About Runtime Class

Two lines in a same program
1.Runtime.getRuntime().exec("notepad");
2.Runtime.getRuntime().exec("dir");
the NotePad is open
but dir command is error
Why? How can i do?
Who can tell me !Thank you

I try, but!
Exception in thread "main" java.io.IOException: CreateProcess: dir >>result.txt
error=2
at java.lang.Win32Process.create(Native Method)
at java.lang.Win32Process.<init>(Win32Process.java:66)
at java.lang.Runtime.execInternal(Native Method)
at java.lang.Runtime.exec(Runtime.java:551)
at java.lang.Runtime.exec(Runtime.java:418)
at java.lang.Runtime.exec(Runtime.java:361)
at java.lang.Runtime.exec(Runtime.java:325)
at test13.main(test13.java:7)
D:\program>

Similar Messages

Need help in using Runtime class

Hi all,
I am facing problem with JRE versions of websphere and SUN JRE. Let me explain my problem.
We have an application working fine in websphere, Now my organization wants to migrate this app to websphere. This application downloads some set of jar files to the client side when the user hits the server with some url. These jar files starts th swing based application in the client side , at the same it will try to communicate with EJB's deployed in the server(Now websphere) to get the data for menus and trees in the swing application. Because of different JRE in the websphere commucation problems like class cast exception are happening. Now we are downloading the the Websphere JRE to the client side and trying to start the application with the downloaded JRE(Even it is not required in case of weblogic in the exiting application also they are downloading the sun JRE). Here the problem starts for me. The execute method of Process class is not able to detect the main class. The waitFor method is returning non zero value. Here is my method.
Can anybody guess what's wrong going on with this code.
public Process spawnProcess(String szSpawnCommand) throws
Exception
          szSpawnCommand = "C:\\ccc\\JRE\\bin\\javaw.exe com.att.suite.client.SuiteAppManager";
          System.out.println("starting processs "+szSpawnCommand);
Process oProcess = null;
try
// oProcess = Runtime.getRuntime().exec(szSpawnCommand);
     Runtime rt = Runtime.getRuntime();
     System.out.println("Got runtime.....");
     oProcess = rt.exec("c:/ccc/JRE/bin/java com.att.suite.client.SuiteAppManager");
     //oProcess.waitFor();
//oProcess = rt.exec("c:/ccc/JRE/bin/javaw -version");
catch (Exception ex)
// Throw an exception with the reason why the process
// couldn't be spawned
// The original message here confused end users - almost always
// occurs due to lack of memory and we cannot determine actual
// reason OS failed to spawn a process.
// Changed to correct LCR MR#: 437
// throw new Exception("Unable to spawn process with command: \"" +
// szSpawnCommand + "\".\nSystem Reason: " + ex.getMessage());
/*throw new Exception("You have insufficient memory to " +
"launch this program. \nPlease quit some other " +
"applications and try again.");*/
     System.out.println("In oProcess.... ");
ex.printStackTrace();
// Wait for a second to give the new process a chance
// to run properly
try
Thread.sleep(1000);
catch (Exception ex)
final DataInputStream oProcStdOutStream = new DataInputStream(
oProcess.getInputStream());
final DataInputStream oProcStdErrStream = new DataInputStream(
oProcess.getErrorStream());
Thread oProcStdOutStreamThread = new Thread()
public void run()
try
String szLine = null;
while ((szLine = oProcStdOutStream.readLine()) != null)
System.out.println("[FromProc1] " + szLine);
catch (Exception ex)
     System.out.println("In oProcStdOutStream");
ex.printStackTrace();
oProcStdOutStreamThread.start();
Thread oProcStdErrStreamThread = new Thread()
public void run()
try
String szLine;
while ((szLine = oProcStdErrStream.readLine()) != null)
System.out.println("[FromProc2] " + szLine);
catch (Exception ex)
ex.printStackTrace();
oProcStdErrStreamThread.start();
// See if the process is still running properly
int nProcessExitValue = 0;
try
nProcessExitValue = oProcess.exitValue();
     // nProcessExitValue = oProcess.waitFor();
     System.out.println("nProcessExitValue : "+nProcessExitValue);
catch (Exception ex)
// This means that the process is still running which
// we'll consider a good sign.
nProcessExitValue = 0;
System.out.println("In nProcessExitValue");
ex.printStackTrace();
// Check the process exit value
if (nProcessExitValue != 0)
// Throw an exception with the return value of the spawned
// process.
// The original message here confused end users - almost always
// occurs due to lack of memory and we cannot determine actual
// reason OS failed to spawn a process.
// Changed to correct LCR MR#: 437
// throw new Exception("Unable to spawn process with command: \"" +
// szSpawnCommand + "\".\nProcess Exit Value: " +
// nProcessExitValue);
throw new Exception("You have insufficient memory to " +
"launch this program. \nPlease quit some other " +
"applications and try again.");
     //System.out.println("In nProcessExitValue!=0");
Here is the error :
starting processs C:\ccc\JRE\bin\javaw.exe com.att.suite.client.SuiteAppManager
Class loaded...
Got runtime.....
nProcessExitValue : 1
[FromProc2] The java class is not found: com/att/launch/jre/Sample
java.lang.Exception: You have insufficient memory to launch this program.
Please quit some other applications and try again.
     at com.att.launch.jre.LaunchApp.spawnProcess(LaunchApp.java:525)
     at com.att.launch.jre.LaunchApp.spawnCJAS(LaunchApp.java:366)
     at com.att.launch.jre.LaunchApp.main(LaunchApp.java:171)
Please help me, I am struggling with this problem from the long time. Or can any body suggest different way to solve this problem instead of downloading the JRE to the client side.
Bhaskar

Hi ,
I am facing problem with JRE versions of websphere and SUN JRE. Let me explain my problem.
We have an application working fine in websphere, Now my organization wants to migrate this app to websphere. This application downloads some set of jar files to the client side when the user hits the server with some url. These jar files starts th swing based application in the client side , at the same it will try to communicate with EJB's deployed in the server(Now websphere) to get the data for menus and trees in the swing application. Because of different JRE in the websphere commucation problems like class cast exception are happening.
     Now we are downloading the the Websphere JRE to the client side and trying to start the application with the downloaded JRE(Even it is not required in case of weblogic in the exiting application also they are downloading the sun JRE).
Here the problem starts for me. The execute method of Process class is not able to detect the main class. The waitFor method is returning non zero value. Here is my method.
Can anybody guess what's wrong going on with this code
public Process spawnProcess(String szSpawnCommand) throws
Exception
          System.out.println("starting processs "+szSpawnCommand);
Process oProcess = null;
try
     Runtime rt = Runtime.getRuntime();
     System.out.println("Got runtime.....");
     oProcess = rt.exec("c:/ccc/JRE/bin/java com.att.suite.client.SuiteAppManager");
catch (Exception ex)
throw new Exception("You have insufficient memory to " +
"launch this program. \nPlease quit some other " +
"applications and try again.");
// Wait for a second to give the new process a chance
// to run properly
try
Thread.sleep(1000);
catch (Exception ex)
final DataInputStream oProcStdOutStream = new DataInputStream(oProcess.getInputStream());
final DataInputStream oProcStdErrStream = new DataInputStream(oProcess.getErrorStream());
Thread oProcStdOutStreamThread = new Thread()
public void run()
try
String szLine = null;
while ((szLine = oProcStdOutStream.readLine()) != null)
System.out.println("[FromProc1] " + szLine);
catch (Exception ex)
     System.out.println("In oProcStdOutStream");
ex.printStackTrace();
oProcStdOutStreamThread.start();
Thread oProcStdErrStreamThread = new Thread()
public void run()
try
String szLine;
while ((szLine = oProcStdErrStream.readLine()) != null)
System.out.println("[FromProc2] " + szLine);
catch (Exception ex)
ex.printStackTrace();
oProcStdErrStreamThread.start();
// See if the process is still running properly
int nProcessExitValue = 0;
try
nProcessExitValue = oProcess.exitValue();
     // nProcessExitValue = oProcess.waitFor();
     System.out.println("nProcessExitValue : "+nProcessExitValue);
catch (Exception ex)
// This means that the process is still running which
// we'll consider a good sign.
nProcessExitValue = 0;
System.out.println("In nProcessExitValue");
ex.printStackTrace();
// Check the process exit value
if (nProcessExitValue != 0)
throw new Exception("You have insufficient memory to " +
"launch this program. \nPlease quit some other " +
"applications and try again.");
Here is the error :
starting processs C:\ccc\JRE\bin\javaw.exe com.att.suite.client.SuiteAppManager
Class loaded...
Got runtime.....
nProcessExitValue : 1
[FromProc2] The java class is not found: com/att/launch/jre/Sample
java.lang.Exception: You have insufficient memory to launch this program.
Please quit some other applications and try again.
     at com.att.launch.jre.LaunchApp.spawnProcess(LaunchApp.java:525)
     at com.att.launch.jre.LaunchApp.spawnCJAS(LaunchApp.java:366)
     at com.att.launch.jre.LaunchApp.main(LaunchApp.java:171)
Please help me, I am struggling with this problem from the long time. Or can any body suggest different way to solve this
problem instead of downloading the JRE to the client side.
Bhaskar

Question About Runtime Class Not Found Exception

Good Morning!
I have a very simple test class that I am using to debug a class loader issue with log4j. I can compile my class. I put the class in a jar file with a manifest that points to the class with the main method. The log4j .jar file is in the .\lib directory, below the test1.jar file. I have fussed around with different variations of -cp & -classpath, without success. I can not figure out why the runtime environment can not load the org.apache.log4j.Logger class.
What is wrong with the way that I am setting up the runtime environment?
Thank you!
==========================
source:
import org.apache.log4j.Logger;
public class Test1 {
    static Logger logger = Logger.getLogger(Test1.class);
    public static void main(String[] args) {
        System.out.println("Hello World");
}===========================
compilation:
X:\test>javac -classpath .\;.\lib\log4j-1.2.14.jar Test1.java
jar:
X:\test>jar -cvmf .\META-INF\MANIFEST.MF test1.jar .\*.class
added manifest
adding: Test1.class(in = 627) (out= 380)(deflated 39%)
MANIFEST.MF:
Manifest-Version: 1.0
Created-By: 1.5.0_11 (Sun Microsystems Inc.)
Main-Class: Test1
==========================
.\lib:
X:\test>dir .\lib
Volume in drive X is Storage
Volume Serial Number is 5871-E6FF
Directory of X:\test\lib
11/25/2009 10:19 PM <DIR> .
11/25/2009 10:19 PM <DIR> ..
11/25/2009 10:05 AM 367,444 log4j-1.2.14.jar
1 File(s) 367,444 bytes
2 Dir(s) 27,042,570,240 bytes free
X:\test>
run:
X:\test>java -client -classpath .\;.\lib\log4j-1.2.14.jar -jar test1.jar
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/log4j/Logger
at Test1.<clinit>(Test1.java:6)
Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Logger
at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)
... 1 more
Could not find the main class: Test1. Program will exit.
X:\test>

Fussing around with the -classpath parameters won't do anything, because they are ignored when the -jar parameter is present. Running an executable jar means that you specified the classpath in the jar's manifest. Which you didn't do. You need a Class-Path entry in the manifest which provides the path to the log4j.jar file relative to your executable jar.

Pls help me about Runtime.getRuntime().exec("java...")

I have two applications. One is Client, the other is Platform.
In the Platform, there are source files packaged into a library named ZtConfig.jar used by Client. If run Client and Platform, two applications can execute normally.
But if Client is started by user from platform, there is something wrong.
I noticed the error difficultly with finally catching exception.
I was puzzled. It is so strange. Pls help me. I list some codes here.
In Client where finally exception catched:
import zt.config;
        try {
          xmlFileUrl = new java.net.URL(
              "file:///e:/Client/src/config/nsr1000.xml");
        catch (IOException ex1) {
          FileLogger.error(ex1.getMessage());
        FileLogger.info("NSR1000Document.setIEDContent", xmlFileUrl.toString());
        try {
          xmlLoader = new XMLConfigLoader(xmlFileUrl);
        finally {
          FileLogger.error("NSR1000Document.setIEDContent",
                           "cannot new XMLConfigLoader object");
          return; // the following codes cannot execute, so have to return here.
In the XMLConfigLoader, the constructor is
public XMLConfigLoader(java.net.URL xmlFileUrl) {
    this.xmlFileUrl = xmlFileUrl;
    configDoc = null;
    builder = null;
    xmlDoc = null;
Platform start Client application using the following code
Runtime.getRuntime().exec(
                "java -jar e:/Client/Client.jar");

I've got it!
Briefly, it is because classpath setting was overwritten by JBuilder.
Firstly, I start Platform from JBuilder. In its messages window. The command is
d:\j2sdk1.4.2_06\bin\javaw -classpath "JBPATH" zt.client.nsr1000.NSR1000App
Now, classpath environment variable was changed to be JBPATH. While I start
Client use Runtime.getRuntime().exec("java -jar Client.jar"), it will not run for classpath changed.
Then, I configured all packages used by Client into JBuilder libraries, including
Client.jar. And changed codes Runtime.getRuntime().exec("java -jar Client.jar") to be Runtime.getRuntime().exec("java -Xmx128m zt.client.nsr1000.NSR1000App")
I also changed CLASSPATH windows system environment variable.
I found this from command console, it can display exceptions. But from JBuilder, there is no exception that can be captured. So debug is difficult.

Help needed with runtime class

i m trying to execute some script by calling the exe to execute it through runtime.exec. it works fine when the script that does not use any library, but if it is using any then it will returns null.
Example:
public static void main(String args[])
Runtime r=Runtime.getRuntime();
p=r.exec(new String[]{"c:/perl/bin/perl.exe","c:/try.pl"});
BufferedReader d= new BufferedReader(new InputStreamReader(p.getInputStream()));
System.out.println(d.readLine());
if try.pl is as following then it prints hello world
print "hello world"
but if it is as following then it prints null
require "cgi-lib.pl"
print "hello world"
so how can i execute scripts with libraries?????????

I don't know Perl but I guess that "require" means the Perl program has to look somewhere else to find another script, or something like that. You know Perl... where does it look? If your answer is that it looks in the current directory, then why haven't you set the current directory?

Help with Runtime class and timeout of Process

Hi,
Question regarding using Runtime class, and yes I have looked at the javadocs, but I am still confused and frustrated.
Here is part of my code.
Process p;
Runtime runtime = Runtime.getRuntime();
p = runtime.exec("rsh localhost ls");
if you are not familiar with rsh all it does is remote shell into the computer localhost and executes the command ls.
Now, I dont have rsh running on my computer so it will hang at that line for about 40 sec and eventually time out on its own. Is there anyway I can specify a timeout argument like there is for the ping command? Like if there is no response from localhost after 3 sec, then just kill the process?
I looked at the Runtime javadoc and Process javadoc and the closest thing I could come to with is something to do with envp (environment parameters), but I dont know what that is.
Thanks guys.

You can't timeout the "runtime.exec("rsh localhost ls");" call but if you execute the call in a seperate thread you can "timeout" and continue executing on the original thread (while letting the "runtime" thread to timeout on its own).
Check the following class that I created for cases like this:
abstract public class TimeoutHelper implements Runnable
    private Throwable error;
    private boolean running = true;
    private Object retValue;
    protected String name;
    private long waitTime;
    private Thread thread;
     * Creates a new helper. Use {@link #start} to run the code.
     * @param name A name that will be used in the helper thread name
     * @param waitTime The time (in msec) to wait before timeout.
    public TimeoutHelper(String name, long waitTime)
        this.name = name;
        this.waitTime = waitTime;
    public Object start() throws Throwable
        return asyncExecute();
    abstract protected Object execute() throws Throwable;
    private synchronized Object asyncExecute() throws Throwable
        createThread().start();
        if (running)
            try
                wait(waitTime);
                if (running)
                    // Timeout!!
                    abortThread();
                    throw new TimeOutException("Timeout for: " + name);
            catch (InterruptedException ie)
                // Ignore
        if (error != null)
            throw error;
        return retValue;
    private void abortThread()
        if (thread != null)
            thread.interrupt();
    protected Thread createThread()
        thread = new Thread(this, name);
        return thread;
    public void run()
        try
            retValue = execute();
        catch (Throwable th)
            error = th;
        synchronized (this)
            running = false;
            notifyAll();
}You use the class by extending it and implementing "execute". For example:
        TimeoutHelper helper = new TimeoutHelper("Runner", 5000)
            protected Object execute() throws Throwable
                Runtime runtime = Runtime.getRuntime();
                return runtime.exec("rsh localhost ls");
        try
            Process p = (Process)helper.start();
        catch (TimeOutException e)
            // Handle timeout here
        catch (Exception e)
            // Handle other errors here.
        }

FTP using Runtime class ...Please Help ??

Hi,
I am trying to ftp a file programatically.
I am trying to use Runtime class but facing problems
in it.This is what I am trying to do :
Runtime rr = Runtime.getRuntime();
String[] cmds = new String[2];
cmds[0]="username=rahmed";
cmds[1]="password=prpas";
try{
Process p = rr.exec("ftp 192.168.1.18",cmds);
rr.exec("put vv.txt");
This does not work ??
Is there any way to make it work ? Or is there any
other way to ftp a file programatically ??
Thanks in adavance..
Regards
Rais

Under Linux/Unix at least, it is good to use the switches -n and -i with the ftp client acually meant for intercative usage.
-i Turns off interactive prompting during multiple file transfers.
-n Restrains ftp from attempting ``auto-login'' upon initial connection.
I do "user <myuser> <mypassword>" then from the script.
I am happily using ftp this way from shell-scripts in my projects.
scp is however better than ftp: it does not send plain text passwords over the net, it support key-based login, its encrypts the data.

Need help about Vector class in java

Hello,
I have some questions about Vector class. Please see this short code:
Vector v = new Vector();
v.add(New Integer(5));
Is this the only way to add int value into vector? Performance wise, is this slow? And are there any better and faster way to add/get int element fro vector?
Thank you very much in advance.

Normally (up to Java version 1.4), that's the only way you can add an int to a Vector. The thing is that Vector can only contain Objects, and an int is a primitive, not an object. So you have to wrap the int in an Integer object.
However, Java 5 has a new feature, called autoboxing, which means that the compiler automatically wraps primitive values into objects, so that you can program it like this:
Vector v = new Vector();
v.add(5);Note, this will not make your program faster or more efficient, because the compiler translates this automatically to:
Vector v = new Vector();
v.add(new Integer(5));So in the end, the same bytecode will be produced. Autoboxing is just a feature to make life more convenient for the programmer.

Question about Runtime.exec

Rob,
Thanks for your help.
I asked a question about a weird Exception on Nov 14, and you told me that I am
using Runtime.exec to start an external process, and that process is crashing.
I am a green-hand on Weblogic, and I am trying to enhancing a project developped
by another person, so I am not familiar with some concepts yet.
Could you please give me some simple explanation about Runtime.exec and external
process?
I found two methods that uses "Runtime" from two classes as following, could you
help me to see whether or not there is something wrong with the usage of Runtime?
Thank you very much.
private int runShellCommand(String command) {
int exitVal = -1;
try {
File runDir = new File(runDirectory);
String[] env = new String[0];
Runtime rt = Runtime.getRuntime();
               double start = System.currentTimeMillis();
Process proc = rt.exec(command, env, runDir);
// Capture output in separate thread
ThreadedStreamReader error = new ThreadedStreamReader(proc.getErrorStream(),
"ERROR");
ThreadedStreamReader output = new ThreadedStreamReader(proc.getInputStream(),
"OUTPUT");
error.start();
output.start();
exitVal = proc.waitFor();
if (logger.isDebugEnabled()) {
     double runtime = (System.currentTimeMillis() - start) / 1000.0;
     logger.info("run " + runId + " " + command + " finished in " + runtime
+ " seconds");
} catch (IOException e) {
logger.fatal("DOE-2 failed \n" + e.getMessage());
} catch (InterruptedException e) {
e.printStackTrace();
return exitVal;
public static void main(String[] args) throws Exception, InterruptedException
final Doe2MessageServer server = new Doe2MessageServer();
while(!connected) {
Thread.sleep(1000);
logger.info("Attempting to start JMS service ...");
               try {
          server.init();
               } catch (Exception ex) {
// shutdown hook to close JMS connection
Runtime.getRuntime().addShutdownHook(
new Thread() {
public void run() {
server.finalize();
server.receiveMessage();

Runtime.exec is a J2SE API. It's not really specific to WLS.
You can read about it here:
http://java.sun.com/j2se/1.4.1/docs/api/java/lang/Runtime.html
It looks like you are starting a JMS Server in a separate process and
that process is crashing.
(You could of course just use WLS's JMS Server instead :>)
-- Rob
Iris Qu wrote:
Rob,
Thanks for your help.
I asked a question about a weird Exception on Nov 14, and you told me that I am
using Runtime.exec to start an external process, and that process is crashing.
I am a green-hand on Weblogic, and I am trying to enhancing a project developped
by another person, so I am not familiar with some concepts yet.
Could you please give me some simple explanation about Runtime.exec and external
process?
I found two methods that uses "Runtime" from two classes as following, could you
help me to see whether or not there is something wrong with the usage of Runtime?
Thank you very much.
private int runShellCommand(String command) {
int exitVal = -1;
try {
File runDir = new File(runDirectory);
String[] env = new String[0];
Runtime rt = Runtime.getRuntime();
               double start = System.currentTimeMillis();
Process proc = rt.exec(command, env, runDir);
// Capture output in separate thread
ThreadedStreamReader error = new ThreadedStreamReader(proc.getErrorStream(),
"ERROR");
ThreadedStreamReader output = new ThreadedStreamReader(proc.getInputStream(),
"OUTPUT");
error.start();
output.start();
exitVal = proc.waitFor();
if (logger.isDebugEnabled()) {
     double runtime = (System.currentTimeMillis() - start) / 1000.0;
     logger.info("run " + runId + " " + command + " finished in " + runtime
+ " seconds");
} catch (IOException e) {
logger.fatal("DOE-2 failed \n" + e.getMessage());
} catch (InterruptedException e) {
e.printStackTrace();
return exitVal;
public static void main(String[] args) throws Exception, InterruptedException
final Doe2MessageServer server = new Doe2MessageServer();
while(!connected) {
Thread.sleep(1000);
logger.info("Attempting to start JMS service ...");
               try {
          server.init();
               } catch (Exception ex) {
// shutdown hook to close JMS connection
Runtime.getRuntime().addShutdownHook(
new Thread() {
public void run() {
server.finalize();
server.receiveMessage();

BCP data into a file using Runtime class

Hi,
     I have a problem in using the Runtime class.
I am trying to bcp a table's data into a file.I am working on a Unix environment.
My bcp is not getting completed fully.The total records to be bcped is 1 million,but only one lakh records is getting bcped and then it hangs up..But if i issue the bcp command from my telnet session it is bcping it to the file without any problem.Can anyone help me out on how to overcome this..
Is there anything specific with Runtime class..I am pasting the code that i tried out below.
String l_s_bcpQuery="bcp mubstage.dbo.HousingUnitSampleMarket out /dun/d3nmb0/mariaps/subracheckprototype -c -t~ -Umariaps -Prykwz5ba -SD3NMB_MUB";
try{
Runtime time=Runtime.getRuntime();
Process p=time.exec(l_s_bcpQuery);
p.waitFor();
System.out.println("The exit value is:"+p.exitValue());
}catch(Exception ioe){
     ioe.printStackTrace();
     System.out.println("IOException"+ioe.getMessage());

you might need to capture the stout & sterr from the process. see http://java.sun.com/j2se/1.4.1/docs/api/java/lang/Process.html, or many other similar questions on this forum.
try this:
try{
Runtime time=Runtime.getRuntime();
Process p=time.exec(l_s_bcpQuery);
BufferedReader stout = new BufferedReader(new InputStreamReader(p.getInputStream()));
BufferedReader sterr = new BufferedReader(new InputStreamReader(p.getErrorStream()));
String out = stout.readLine();
String err = sterr.readLine();
while((out != null)||(err != null))
if(out != null)
System.out.println(out);
if(err != null)
System.err.println(err);
out = stout.readLine();
err = sterr.readLine();
int exit_value = p.waitFor();
System.out.println("The exit value is:"+ exit_value);
}catch(Exception ioe){
ioe.printStackTrace();
System.out.println("IOException"+ioe.getMessage());
}

To ragnic and other about Singleton class

Hi ragnic. Thanks for your reply. I posted the code wrong. Heres' my correct one.
I have a GUI first loaded information and the information is stored in a databse, I have some EJB classes..and my singleton class ABC has some method to access to the EJB..
so my first GUI will gather info using singleton class and later if I click on
a button in my first GUI class, will pop up another frame of another class , this class also need to class setPassword in my Singleton..
are my followign codes correctly??
iS my Class ABC a SINgleton class? thanks
Is my class ABC use as single correctly. And It is called from other classes is also correct?
I'm new to java and like to learn about Singleton class.
But I really dont' understand it clearly after reading many examples of it.
I have a project to convert my class abc to a singleton.
But I dont know how to do it.
In my class(soon will become a singleton) will have few methods that later I need to use it from another class A and class B.
I have a GUI application that first load my class A..and my class will call
class abc(singleton) to get some information from it.
and then in class A has a button, if I click on that button I will call SIngleton class again to update my password, in the singleton class has method calls updatePassword. But I dont know how to call a singleton from other class.
I have my code for them below:
1)public class ABC //attempt using a singleton
private static ABC theABC = null;
private ABC(){}
public synchronized static ABC getABC()
if(theABC == null)
theABC= new ABC();
return the ABC;
public void updateUserInfo(SimpleUser user)
throws UserNotFoundException, DelegateException
try
UserCollectionHome userCollectionHome = (UserCollectionHome)
EJBHomeFactory.getFactory().lookupHome("vista/UserCollection",
UserCollectionHome.class);
UserHome userHome = (UserHome)
EJBHomeFactory.getFactory().lookupHome("vista/User",UserHome.class);
UserCollection uc = userCollectionHome.create();
uc.updateUserInfo(user, userHome);
} catch(HomeFactoryException hfe) {
hfe.printStackTrace();
throw new DelegateException(hfe);
} catch(RemoteException re) {
re.printStackTrace();
throw new DelegateException(re);
} catch(CreateException ce) {
ce.printStackTrace();
throw new DelegateException(ce);
} catch(FinderException fe) {
fe.printStackTrace();
throw new UserNotFoundException();
public SimpleUser getID(String id)
throws UserNotFoundException, DelegateException
try
UserCollectionHome userCollectionHome = (UserCollectionHome)
EJBHomeFactory.getFactory().lookupHome("vista/UserCollection",
UserCollectionHome.class);
UserHome userHome = (UserHome)
EJBHomeFactory.getFactory().lookupHome("vista/User",UserHome.class);
UserCollection uc = userCollectionHome.create();
SimpleUser su = uc.getID(id, userHome);
return su;
} catch(HomeFactoryException hfe) {
throw new DelegateException(hfe);
} catch(RemoteException re) {
throw new DelegateException(re);
} catch(CreateException ce) {
throw new DelegateException(ce);
} catch(FinderException fe) {
throw new UserNotFoundException();
public void setPassword(String lname,String pw)
throws UserNotFoundException, DelegateException
try
UserCollectionHome userCollectionHome = (UserCollectionHome)
EJBHomeFactory.getFactory().lookupHome("vista/UserCollection",
UserCollectionHome.class);
UserHome userHome = (UserHome)
EJBHomeFactory.getFactory().lookupHome("vista/User",UserHome.class);
UserCollection uc = userCollectionHome.create();
uc.setPassword(lname,pw, userHome);//assume that all lname are differents.
} catch(HomeFactoryException hfe) {
hfe.printStackTrace();
throw new DelegateException(hfe);
} catch(RemoteException re) {
re.printStackTrace();
throw new DelegateException(re);
} catch(CreateException ce) {
ce.printStackTrace();
throw new DelegateException(ce);
} catch(FinderException fe) {
fe.printStackTrace();
throw new UserNotFoundException();
}//Do I have my class as a Singleton correctly???
2)//Here is my First Frame that will call a Singleton to gather user information
public A(Frame owner)
super(owner, "User Personal Information",true);
initScreen();
loadPersonalInfo();
* This method instantiates all the GUI widgets and places them into panels and
* onto the frame.
private void initScreen()
txtFname = new JTextField(20);
txtLname=new JTextField(20);
btnsave =new JButton("Save");
btnChange= new JButton("Click here to change PW");//when you click this button there will be a frame pop up for you to enter informaton..this iwll call class B
JPanel pnlMain=new JPanel();
JPanel pnlFname= new JPanel();
pnlFname.setLayout(new BoxLayout(pnlFname, BoxLayout.X_AXIS));
pnlFname.setBorder(BorderFactory.createEmptyBorder(0,87,0,90));
pnlFname.add(new JLabel("First Name:"));
pnlFname.add(Box.createRigidArea(new Dimension(5,0)));
pnlFname.add(txtFname);
JPanel pnlLname= new JPanel();
pnlLname.setLayout(new BoxLayout(pnlLname, BoxLayout.X_AXIS));
pnlLname.setBorder(BorderFactory.createEmptyBorder(0,87,0,90));
pnlLname.add(new JLabel("Last Name:"));
pnlLname.add(Box.createRigidArea(new Dimension(5,0)));
pnlLname.add(txtLname);
pnlMain.add(pnlFname);
pnlMain.add(pnlLname);
pnlMain.add(btnsave);
pnlMain.add(btnChange");
btnSave = new JButton("Save");
btnSave.setActionCommand("SAVE");
btnSave.addActionListener(this);
btnCancel = new JButton("Cancel");
btnCancel.setActionCommand("CANCEL");
btnCancel.addActionListener(this);
JPanel pnlBottom = new JPanel();
pnlBottom.setLayout(new BoxLayout(pnlBottom, BoxLayout.X_AXIS));
pnlBottom.setBorder(BorderFactory.createEmptyBorder(25,55,0,0));
pnlBottom.add(btnSave);
pnlBottom.add(Box.createRigidArea(new Dimension(25,0)));
pnlBottom.add(btnCancel);
pnlMain.add(pnlBottom);
this.setContentPane( pnlMain);
setSize(500,500);
GraphicUtilities.center(this);
theABC=ABC.getABC();
//Do I call my ABC singleton class correctly??
private void loadPersonalInfo()
String ID= System.getProperty("user.name");
SimpleUser user = null;
try {
user = ABC.getID(ID);
//I tried to use method in ABC singleton class. IS this correctly call?
} catch(UserNotFoundException nfe)
JOptionPane.showMessageDialog(new JDialog(),"You have not yet registered.",
"User Not Found",JOptionPane.WARNING_MESSAGE);
System.exit(0);
} catch(DelegateException de) {
JOptionPane.showMessageDialog(new JDialog(),"You have not yet registered",JOptionPane.ERROR_MESSAGE);
System.exit(0);
currentUser = user;
txtFname.setText(currentUser.getFirstName());
txtLname.setText(currentUser.getLastName());
//This information will be display in my textfields Fname and Lname
//I can change my first and last name and hit button SAVE to save
public void actionPerformed(ActionEvent e)
if(e.getActionCommand().equals("SAVE")) submitChanges();
if(e.getActionCommand().equals("CHANGE_PASSWORD")) {
changepassword=new ChangePassword(new Frame(),name,badgeid);
public void submitChanges(){
String currentNTUsername = System.getProperty("user.name");
SimpleUser user =null;
try {
user = theABC.getID(ID);
user.setFirstName(txtFname.getText().trim());
user.setLastName(txtLname.getText().trim());
currentUser = user;
theABC.updateUserInfo(currentUser);
//IS this correctly if I want to use this method in singleton class ABC??
} catch(UserNotFoundException nfe)
JOptionPane.showMessageDialog(new JDialog(),"You have not yet registered",
"User Not Found",JOptionPane.WARNING_MESSAGE);
} catch(DelegateException de) {
JOptionPane.showMessageDialog(new JDialog(),"You have not yet registered",JOptionPane.ERROR_MESSAGE);
System.exit(0);
this.setVisible(false);
3) click on ChangePassword in my above GUI class A..will call this class B..and in this class B
I need to access method in a Singleton class- ABC class,,DO i need to inititates it agian, if not what should I do? thanks
package com.lockheed.vista.userinfo;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.border.*;
import javax.swing.table.*;
import javax.swing.tree.*;
import java.util.StringTokenizer;
import java.util.Vector;
import java.io.*;
import javax.swing.text.*;
import javax.swing.text.html.*;
import javax.swing.colorchooser.*;
import javax.swing.filechooser.*;
import javax.accessibility.*;
import java.beans.*;
import java.applet.*;
import java.net.*;
import org.apache.log4j.*;
import com.lockheed.common.gui.GraphicUtilities;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.border.*;
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import vista.user.UserServicesDelegate;
import vista.user.SimpleUser;
import vista.user.UserNotFoundException;
import vista.user.*;
import com.lockheed.common.ejb.*;
import com.lockheed.common.gui.*;
import com.lockheed.vista.publish.*;
* This program allow users to change their Vista Web Center's password
public class ChangePassword extends JDialog
implements ActionListener{
protected final Logger log = Logger.getLogger(getClass().getName());
private UserServicesDelegate userServicesDelegate;
private User currentUser = null;
private JPasswordField txtPasswd, txtVerifyPW;
private JButton btnSubmit,btnCancel;
private JLabel lblName,lblBadgeID;
private String strBadgeID="";
* This is the constructor. It creates an instance of the ChangePassword
* and calls the method to create and build the GUI.
public ChangePassword(Frame owner,String name,String badgeid)
super(owner, "Change Password",true);
initScreen(name,badgeid);//build the GUI
* This method instantiates all the GUI widgets and places them into panels and
* onto the frame.
private void initScreen(String strname,String strBadgeid)
txtPasswd = new JPasswordField(20);
txtVerifyPW=new JPasswordField(20);
txtPasswd.setEchoChar('*');
txtVerifyPW.setEchoChar('*');
JPanel pnlMain=new JPanel();
pnlMain.setLayout(new BoxLayout(pnlMain, BoxLayout.Y_AXIS));
pnlMain.setBorder(BorderFactory.createEmptyBorder(20,0,20,0));
JPanel pnlPW=new JPanel();
pnlPW.setLayout(new BoxLayout(pnlPW, BoxLayout.X_AXIS));
pnlPW.setBorder(BorderFactory.createEmptyBorder(0,96,0,30));
pnlPW.add(new JLabel("Password:"));
pnlPW.add(Box.createRigidArea(new Dimension(5,0)));
pnlPW.add(txtPasswd);
JPanel pnlVerifyPW=new JPanel();
pnlVerifyPW.setLayout(new BoxLayout(pnlVerifyPW, BoxLayout.X_AXIS));
pnlVerifyPW.setBorder(BorderFactory.createEmptyBorder(0,63,0,30));
pnlVerifyPW.add(new JLabel("Verify Password:"));
pnlVerifyPW.add(Box.createRigidArea(new Dimension(5,0)));
pnlVerifyPW.add(txtVerifyPW);
JPanel pnlTop= new JPanel();
pnlTop.add(pnlPW);
pnlTop.add(Box.createRigidArea(new Dimension(0,10)));
pnlTop.add(pnlVerifyPW);
pnlMain.add(pnlTop);
btnSubmit = new JButton("Submit");
btnSubmit.setActionCommand("SUBMIT");
btnSubmit.addActionListener(this);
btnCancel = new JButton("Cancel");
btnCancel.setActionCommand("CANCEL");
btnCancel.addActionListener(this);
JPanel pnlBottom = new JPanel();
pnlBottom.setLayout(new BoxLayout(pnlBottom, BoxLayout.X_AXIS));
pnlBottom.setBorder(BorderFactory.createEmptyBorder(25,55,20,30));
pnlBottom.add(btnSubmit);
pnlBottom.add(Box.createRigidArea(new Dimension(25,0)));
pnlBottom.add(btnCancel);
pnlMain.add(pnlBottom);
this.setContentPane( pnlMain);
setSize(350,230);
setVisible(true);
public void actionPerformed(ActionEvent e)
if(e.getActionCommand().equals("CANCEL")) this.setVisible(false);
if(e.getActionCommand().equals("SUBMIT")) submitPW();
* This method is called when the submit button is clicked. It allows user to change
* their password.
public void submitPW(){
myABC= ABC.getABC();//Is this correct?
char[] pw =txtPasswd.getPassword();
String strPasswd="";
for(int i=0;i<pw.length;i++){
strPasswd=strPasswd+pw;
char[] vpw =txtVerifyPW.getPassword();
String strVerifyPW="";
for(int i=0;i<vpw.length;i++){
strVerifyPW=strVerifyPW+pw;
if((strPasswd==null)||(strPasswd.length()==0)) {
JOptionPane.showMessageDialog(new JDialog(),"You have not enter a password. Please try again.",
"Invalid Password",JOptionPane.ERROR_MESSAGE);
if((!strPasswd.equals(strVerifyPW)))
//password and verify password do not match.
JOptionPane.showMessageDialog(new JDialog(),"Your passwords do not match. Reenter and try again.",
"Invalid Password",JOptionPane.ERROR_MESSAGE);
try
myABC.setUserPassword(strPasswd);//try to use a method in Singleton class
txtPasswd.setText("");
txtVerifyPW.setText("");
this.setVisible(false);
} catch(DelegateException e) {
JOptionPane.showMessageDialog(new Frame(),
"Error.",
"Unable to change password information.",JOptionPane.WARNING_MESSAGE);
} catch(UserNotFoundException e) {
JOptionPane.showMessageDialog(new Frame(),
"Error.",
"Unable to change password information.",JOptionPane.WARNING_MESSAGE);
And ofcourse I have other EJB classes to work with these classes.
***It compiles okey but when I ran, it say "NullPointerException"
I think I call my Singleton wrong.
Please help me.thanks

1. When replying, use <reply>, don't post a new topic.
2. Implementing a singleton is a frequently asked question. Search before you post.
3. This is not a question about Swing. A more appropriate forum would be "New To Java Technology" or perhaps "Java Programming", but see point 1.
4. When posting code, keep it short. It increases the chance of readers looking at it. And in composing your shorter version for the forum, you just may solve your problem.

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