Create class in java. package

Not good practice, I know, but is it it possible to do. It seems as the VM (1.3) does not bother about if I set up the RuntimePermissions to be able to access and define Class In Package java.net. I still get a prohibited package name exception.
Anyone that knows something about it?
I tried to create a class in java.net with these permissions defined in pollicy file
permission java.lang.RuntimePermission "defineClassInPackage.java.net";
permission java.lang.RuntimePermission "accessClassInPackage.java.net";
//Rickard

Try loading your classes through the bootstrap java command option (see below).
Let us know how you fare,
Manuel Amago.
Boostrap command line options
-Xbootclasspath:<directories and zip/jar files separated by ;>
set search path for bootstrap classes and resources
-Xbootclasspath/a:<directories and zip/jar files separated by ;>
append to end of bootstrap class path
-Xbootclasspath/p:<directories and zip/jar files separated by ;>
I would use the option in the middle.

Similar Messages

Yet another ALERT: Cannot create class in system package

I've searched on the forums and seen several postings and none that really explained a solution, just the initial poster replying they fixed the problem. I am new to J2ME and java in general, I'm going off a book and my first test worked fine but this one gives me the the ALERT: Cannot create class in system package, when I select the GO command. The error occurs in the commandAction method where command == go trying to create an alert message. I am using MIDP 2.0 and as I stated new to this whole thing so a detail response would be greatly appreciated and what I need to do to resolve this for now and the future.
Source code for TextBoxTest.java :
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
public class TextBoxTest extends MIDlet implements CommandListener
   private TextBox textBox;
   private Alert alert;
   private Command quit;
   private Command go;
   public TextBoxTest()
      // Setup the UI
      textBox = new TextBox("Enter Name", "", 20, TextField.ANY);
      go = new Command("Go", Command.SCREEN, 1);
      quit = new Command("Quit", Command.EXIT, 2);
      textBox.addCommand(go);
      textBox.addCommand(quit);
      textBox.setCommandListener(this);
   protected void startApp() throws MIDletStateChangeException
      Display.getDisplay(this).setCurrent(textBox);
   protected void pauseApp()
   protected void destroyApp(boolean unconditional)
        throws MIDletStateChangeException
   public void commandAction(Command command, Displayable displayable)
      try
         if (command == quit)
            destroyApp(true);
            notifyDestroyed();
         if (command == go)
            alert = new Alert("", "Greetings " + textBox.getString(), null,
AlertType.CONFIRMATION);
            Display.getDisplay(this).setCurrent(alert);
      catch (MIDletStateChangeException me)
         System.out.println(me + " caught.");
}

Ok so my problem isn't with the code it's with the build order. I guess I needed to state that I was following a book and trying to compile and preverify through command line and not using the toolkit or an IDE. So if I use NetBeans 5.0 or the Wireless Toolkit 2.5 I can compile fine.
So my new question is, can someone show me the steps to build through command line? This is MIDP 2.0.

Cannot create class in system package

Hello,
I wrote a J2ME game for nokia S40 phones. It compiles without any errors, but when I'm trying to run in on the Nokia 7210 phone emulator I receive the following message:
Cannot create class in system package.
Howerver running on the Nokia 6230 phone emulator is ok.
I have obfuscated my applet as I read in previous topics, but still it does not work.
Can anyone help me?
Thanks,
Alexander.

You get that error when you try to reference a class that is part of the MIDP framework but isn't installed on the phone.
The 7210 doesn't support MMAPI or WMA or MIDP 2.0, while the 6230 does, so check that you don't have any references (even an import statement), to classes from those packages (like the javax.microedition.media.*, javax.microedition.lcdui.game.*,javax.wireless.messaging.*, etc. packages hierarchies).
shmoove

Cannot create class in system package while Using Sprite class

Hi i developed a game using Sprite class & imported
javax.microedition.lcdui.game.*; package. But when i tried to build this project it gave me "Cannot create class in system package" error. Worst thing is that now again if i build, then it displays error "package javax.microedition.lcdui.game.*; does not exist" . Pls help me

First exception means that you tried to create a class with the package name equaling one from the predefined libraries in midp/cldc.
For your second error, add all the jars you are using into the project's classpath.
Mihai

Jsr 180 cannot create class in system package.

Hi,
I am trying to run the jsr 180 api sip-example midlets from jbuilder. The project buildes fien but when I run it I get the following:
C:\JBuilderX\j2mewtk2.0\bin\emulator.exe -Xdevice:DefaultColorPhone -Xdescriptor:"C:\Documents and Settings\aishling\jbproject\aisling\lib\sip-examples.jad"
Running with storage root DefaultColorPhone
ALERT: Cannot create class in system package
Execution completed successfully
398951 bytecodes executed
8 thread switches
434 classes in the system (including system classes)
2473 dynamic objects allocated (82448 bytes)
3 garbage collections (58908 bytes collected)
From going through the archives, I thought I should change the name of the package. So I renamed the directory containing the midlet files from /src/examples to /src/aisexamples and updated each file to include package aisexamples. However this just results in another error (22 + 14) unable to create MIDlet aisexamples.
Please, please can someone let me know whats going on?
Thanks,
Aisling.

i m also facing the same prob can any body help us

Create Classes In Different Packages With Error-free Importing

Hello,
I'd like to create a class which inherits from another class from some other package. So I use "import" keyword to involve the class to build my new class on. However, I hope my new class can be in its own package which is different with one the base class is in. To make it clear, please see the example below:
There are two folders, with name c08 and c09 respectively, in C:\Java which I created for this case. I set the environment variable as C:\Java. There is no problem. Then I saved file "Inter.java" in C:\Java\c08. It's source code is as below:
package c08;
public interface Inter {
     void play ();
     void action ();
And another "Test.java" is saved in C:\Java\c09. Source code as below:
package c09;
import c08.*;
public class Test {
protected class PC implements Inter {
          public void play () {
               System.out.println("Play()");
          public void action () {
               System.out.println("Action()");
It was successfully compiled for "Inter.java". But when comes to "Test.java", it failed with error message of something like "Cannot find the interface Inter". I tried some other ways and I didn't get any results.
I hope to create a class using classes from some other packages while keeping the new one in a different package. How can this be done? (I am currently doing this in J2SE 1.4.01 under Windows XP Home Edition)
Thank you!
Best Regards
Felix

I copied and pasted your code as well as made c08 and c09 directories. I had no errors compiling. I am using NT, but it appears that your problem is Classpath related. You can try to CD to the C:\Java directory and compile using "javac c09\Test.java" That's the command I used.

Unable to compile ( not creating class file ) java file

Hi
I am unable to compile java file in eclipse. I am using Tomcat 5.0 and eclipse 3.0. I am able to compile the file from command prompt. I installed eclipse and did all settings including Build path ( WEB-INF\classes). But I donot see any class file getting created.

Are you seeing errors when eclipse compiles you classes? Have you tried to build your project using; Project -> Build All? If you have and it looks like no errors are generated you may need to change your perspective. Try changing to the resource perspective to see the built class files; Window -> Open Perspective -> Other -> Resource. By default built class files end up in the bin directory of the project. i usually change my built classes directory to classes, just makes more sense to me.

Using ExecutorService class from java.util.concurrent package

Dear java programmers,
I have a question regarding the ExecutorService class from java.util.concurrent package.
I want to parse hundreds of files and for this purpose I'm implementing a thread pool. The way I use the ExecutorService class is summarized below:
ExecutorService executor = Executors.newFixedThreadPool(10);
        for (int i = 0; i < 1000; i++){
            System.out.println("Parsing file No "+i);
            executor.submit(new Dock(i));
        executor.shutdown();
        try {
            executor.awaitTermination(30, TimeUnit.SECONDS);
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        executor.shutdownNow();However, the code snippet above creates all the 1000 threads (Dock objects) at once and loads them to the executor, and thus I'm worrying about memory leak. I haven't tested it on 1000 files yet but just on 50 small ones, and even if the program prints out "Parsing file No "+i 50 times at once, it executes normally the threads in the background.
I guess the write way would be to keep the number of active/idle threads in the executor constant (lets say 20 if the thread pool's size is 10) and submit a new one whenever a thread has been finished or terminated. But for this to happen the program should be notified someway whenever a thread is done. Can anybody help me do that?
thanks in advance,
Tom

Ok I found a feasible solution myself although I'm not sure if this is the optimum.
Here's what I did:
        ExecutorService executor = Executors.newFixedThreadPool(10);
        Future<String> future0, future1, future2, future3, future4, future5, future6, future7, future8, future9;
        Future[] futureArray = {future0 = null, future1 = null, future2 = null, future3 = null, future4 = null, future5 = null,
        future6 = null, future7 = null, future8 = null, future9 = null};
        for (int i = 0; i < 10; i++){
            futureArray[i] = executor.submit(new Dock(i));
        }I created the ExecutorService object which encapsulates the thread pool and then created 10 Future objects (java.util.concurrent.Future) and added them into an Array.
For java.util.concurrent.Future and Callable Interface usage refer to:
[http://www.swingwiki.org/best:use_worker_thread_for_long_operations]
[http://www.particle.kth.se/~lindsey/JavaCourse/Book/Part1/Java/Chapter10/concurrencyTools.html]
I used a Future[] Array to make the code neater. So after that I submitted -and in this way filled up- the first 10 threads to the thread pool.
        int i = 9;
        while (i < 1000){
            for (int j = 0; j < 10; j++){
                if (futureArray[j].isDone() && i < 999){
                    try{
                        i++;
                        futureArray[j] = executor.submit(new Dock(i));
                    } catch (ExecutionException ex) {
                        ex.printStackTrace();
                    } catch (InterruptedException ex) {
                        ex.printStackTrace();
            try {
                Thread.sleep(100); // wait a while
            } catch(InterruptedException iex) { /* ignore */ }
        executor.shutdown();
        try {
            executor.awaitTermination(60, TimeUnit.SECONDS);
        } catch (InterruptedException ex) {
            ex.printStackTrace();
        executor.shutdownNow();
    }Each of the future[0-9] objects represents a thread in the thread pool. So essentially I'm check which of these 10 threads has been finished (using the java.util.concurrent.Future.isDone() method) and if yes I replenish that empty future[0-9] object with a new one.

Import the classes in the package java.util

I haven't taken a class in two years so I have ideas but am unsure of myself, and I most likely am way off base, but is this how you import the classes in the package java.util
import java.util.*;
I would appreciate anyone's help. I have a lot of questions.
Thanks,
rp

My assignment is below so that you will know exactly what I am asking. I am being asked to create an instance of LinkedList. I know that this is a part of the java.util. So when you create an instance of LinkedList would that be similar to instance variables? or am I misunderstanding something. I have several ideas, so I will start with the first one.
LinkList();
I really appreciate your taking the time to answer my questions to help me to rebuild my confidence in doing this.
Thanks,
// 2. import the classes in the package java.util
public class MyProgram
     public static void main(String [] args)
          // 3. Create an instance of LinkedList
          // 4. add 5 entries to the list so that it contains
          //     Ann, Bart, Carl, Dirk, Zak
          // 5. display the list on one line using a loop and ADT list methods
          System.out.println("\n\n3. ");
          // 6. display the list using one println
          System.out.println("\n\n4. ");
          // 7. create a ListIterator object for the list
          // 8. display the list on one line using the iterator
          System.out.println("\n\n6. ");
          // 9. restore the iterator to the first item in the list
          // 10. retrieve and display the first item in the iteration,
          //      then advance the iterator to the next item
          System.out.println("\n\n8. ");
          // 11. advance the iterator to the end of the list without displaying anything;
          //      do not use the length of the list
          // 12. display the last item in the list
          System.out.println("\n\n10. ");
          // 13. move back to the beginning of the list without displaying anything;
          //      do not use the length of the list
          // 14. display the first item in the list
          System.out.println("\n\n12. ");
          // 15. advance the iterator to the end of the list without displaying anything;
          // 16. advance the iterator - what happens?
          System.out.println("\n\n14. ");
          // 17. advance the iterator within a try block; catch the exception, display a message,,
          //      and set the iterator back to the beginning of the list.
          System.out.println("\n\n15. ");
          // 18. what does nextIndex and previousIndex return?
          System.out.println("\n\n16. ");
          // 19. move the iterator to the third item in the list; if you were to
          //      execute next(), the third item would be returned and the iterator
          //      would advance to the 4th item.
          System.out.println("\n\n17. ");
          // 20. add the string "New" to the list; where is it inserted relative to
          //      the current item in the iteration?
          System.out.println("\n\n18. ");
          // 21. remove the current item; what happens?
          System.out.println("\n\n19. ");
          // 22. display the current item in the list without advancing the iteration
          //      in 2 ways, as follows:
          // 22A - using only iterator methods
          System.out.println("\n\n20A. ");
          // 22B using an iterator method and list methods
          System.out.println("\n\n20B. ");
          // 23. advance the iterator and remove the current item; which one is removed?
          System.out.println("\n\n21. ");
          // 24. move the iterator back and remove the current item; which one is removed?
          System.out.println("\n\n22. ");
          // 25. move the iterator to the first item in the list and change it to "First"
          System.out.println("\n\n23. ");
     } // end main
} // end MyProgram

How do we create self-signed certificate using java packages

Hi All,
I require some information on creating self-signed certificate using java packages.
The java.security.cert.* package allows you to read Certificates from an existing store or a file etc. but there is no way to generate one afresh. See CertificateFactory and Certificate classes. Even after loading a certificate you cannot regenerate some of its fields to embed the new public key – and hence regenerate the fingerprints etc. – and mention a new DN. Essentially, I see no way from java to self-sign a certificate that embeds a public key that I have already generated.
I want to do the equivalent of ‘keytool –selfcert’ from java code. Please note that I am not trying to do this by using the keytool command line option – it is always a bad choice to execute external process from the java code – but if no other ways are found then I have to fall back on it.
Regards,
Chandra

I require some information on creating self-signed certificate using java packages. Its not possible because JCE/JCA doesn't have implementation of X509Certificate. For that you have to use any other JCE Provider e.g. BouncyCastle, IAIK, Assembla and etc.
I'm giving you sample code for producing self-signed certificate using IAIK JCE. Note that IAIK JCE is not free. But you can use BouncyCastle its open source and free.
**Generating and Initialising the Public and Private Keys*/
public KeyPair generateKeys() throws Exception
      //1 - Key Pair Generated [Public and Private Key]
      m_objkeypairgen = KeyPairGenerator.getInstance("RSA");
      m_objkeypair = m_objkeypairgen.generateKeyPair();
      System.out.println("Key Pair Generated....");
      //Returns Both Keys [Public and Private]*/
      return m_objkeypair;
/**Generating and Initialising the Self Signed Certificate*/
public X509Certificate generateSSCert() throws Exception
    //Creates Instance of X509 Certificate
    m_objX509 = new X509Certificate();
    //Creatting Calender Instance
    GregorianCalendar obj_date = new GregorianCalendar();
    Name obj_issuer = new Name();
    obj_issuer.addRDN(ObjectID.country, "CountryName");
    obj_issuer.addRDN(ObjectID.organization ,"CompanyName");
    obj_issuer.addRDN(ObjectID.organizationalUnit ,"Deptt");
    obj_issuer.addRDN(ObjectID.commonName ,"Valid CA Name");
    //Self Signed Certificate
    m_objX509.setIssuerDN(obj_issuer); // Sets Issuer Info:
    m_objX509.setSubjectDN(obj_issuer); // Sets Subjects Info:
    m_objX509.setSerialNumber(BigInteger.valueOf(0x1234L));
    m_objX509.setPublicKey(m_objkeypair.getPublic());// Sets Public Key
    m_objX509.setValidNotBefore(obj_date.getTime()); //Sets Starting Date
    obj_date.add(Calendar.MONTH, 6); //Extending the Date [Cert Validation Period (6-Months)]
    m_objX509.setValidNotAfter(obj_date.getTime()); //Sets Ending Date [Expiration Date]
    //Signing Certificate With SHA-1 and RSA
    m_objX509.sign(AlgorithmID.sha1WithRSAEncryption, m_objkeypair.getPrivate()); // JCE doesn't have that specific implementation so that why we need any //other provider e.g. BouncyCastle, IAIK and etc.
    System.out.println("Start Certificate....................................");
    System.out.println(m_objX509.toString());
    System.out.println("End Certificate......................................");
    //Returns Self Signed Certificate.
    return m_objX509;
//****************************************************************

Import java class from model package

I have a java class in model package.I create a managed bean in the view package and I want to import the first java class with "import model.class1" but this error "import model.class1 not found" is shown.What should I do?

Hi,
Why are you importing the Model classes to your backing bean? You should not be doing that. Instead, expose the method in model as client interface (whichever you want to call in the backing bean), create the method binding in your pagedef. Then, from the backing bean, you can execute the method programatically.
-Arun

Does Java package has Model class?

I found the following code below from http://java.sun.com/blueprints/guidelines/designing_enterprise_applications_2e/web-tier/web-tier5.html. The problem is there is no Model class during the java compilation. I thought it is included in the Java package. Anyway, I was fail to import the Model class from java.lang.Object, java.awt, java.awt.event.*, javax.swing.*, java.util.*, and so on. Does Model class belong to Java package or self create?
// Action.java:
public abstract class Action {
protected Model model;
public Action(Model model) { this.model = model; }
public abstract String getName();
public abstract Object perform(HttpServletRequest req);
// CreateUserAction.java:
public class CreateUserAction extends Action {
public CreateUserAction(Model model) {
    super(model);
public String getName() { return "createUser"; }
public Object perform(HttpServletRequest req) {
    return model.createUser(req.getAttribute("user"),
                  req.getAttribute("pass"));
}

No, it's not a Java SDK class, and it doesn't self-create. It must be part of the blueprints download, so you'll have to find where it is (a JAR file you've downloaded, perhaps) and put it in the CLASSPATH.

How to create a class using java script..

Hi all,
Iam new to java script and I tried out the following program but its not working..I basically created a class just like a java prog' but Iam not getting any output or error.Iam attaching the code below.
If I created one function inside the script and create one object its working fine but what should I do when I have a lot of function??so I created a class and put all the function and created an object but its not working..
Do let me know what changes should I do..Iam attaching the code which I had written. or give me an example of how to create a class with couple of functions using JAVASCRIPT
Thanks
Avis_su
<html>
<head><title>JSP Page</title></head>
<body>
<SCRIPT language = "JavaScript">

</script>
</body>
</html>

Run this program to get your answer:
public class AnswerToYourPost {
public static void main(String args[]) {
System.out.println("TRUE/FALSE: This question
ion belongs on a Java forum.\n"
+ "ANSWER: " + ("Javascript" == "Java"));
}Since when do we compare objects for equality using operator == ?

How to find classes in a java package

i am writing a java IDE. i want to extract all class names from a java package eg. java.lang (through coding). how can i do that.
Thanks in advance

File file = new File("path to your jar file");
JarFile jf = new JarFile(file);
Enumeration e = jf.entries();
ZipEntry ze = null;
while(e.hasMoreElements()){
ze = (ZipEntry) e.nextElement();
ze.toString(); // gives you the file name
you have to understand java.util.jar java.util.zip packages for working with jar/zip files.
Hope this helps

Problem creating in some attribute options for class through java API

Hello everyone,
I am successfully creating class and its attributes but i am not able to create attributes with its option like IS REQUIRED, IS INDEXED, IS SETTABLE and READ ONLY.....
public void create_class(String cname,String cdesc,String scname)
try
ClassObjectDefinition cod = new ClassObjectDefinition(csession);
cod.setSuperclassName(scname);
cod.setName(cname);
ClassObject co = (ClassObject)csession.createSchemaObject(cod);
AttributeDefinition ad2 = new AttributeDefinition(csession);
ad2.setAttributeByUpperCaseName("NAME",AttributeValue.newAttributeValue("Divya"));
ad2.setAttributeByUpperCaseName("DATATYPE",AttributeValue.newAttributeValue(Attribute.ATTRIBUTEDATATYPE_STRING));
ad2.setAttributeByUpperCaseName("DATALENGTH",AttributeValue.newAttributeValue(151));
ad2.setAttributeByUpperCaseName("DESCRIPTION",AttributeValue.newAttributeValue("This the attribute number 2"));
//here is some problem,,, Is Required is not been able to set
//ad2.setAttributeByUpperCaseName("REQUIRED",AttributeValue.newAttributeValue(true));
co.addAttribute(ad2);
catch(IfsException e)
e.printStackTrace();
}

Hi Kabilesh,
Could you please let me know the exast soution u had for this?
I even set the SHLIB_PATH in the environment, but still this problem persists.
I am compiling the program and making into a shared library as
cc -c -g -n +z -I$JAVA_HOME/include -I$JAVA_HOME/include/hp-ux -L/opt/java1.4/jre/lib/PA_RISC2.0/server -ljvm Test.c -o Test.o
ld -b Test.o -L/opt/java1.4/jre/lib/PA_RISC2.0/server -ljvm -o Test.slMy java code is looks like this :
void create_Jvm()
    JNIEnv * env;
    JavaVM * jvm;
    //JDK1_1InitArgs vm_args;
    /* Note : In JNI1.2 and Java2 SDK 1.4, the new structure JavaVMInitArgs has been introduced.*/
    JavaVMInitArgs vm_args;
    //JavaVMOption options[1];
    jint res;
    vm_args.nOptions = 0;
    vm_args.ignoreUnrecognized = JNI_TRUE;
    /* IMPORTANT: specify vm_args version # if you use JDK1.1.2 and beyond */
    vm_args.version = JNI_VERSION_1_4;
    //vm_args.version = JNI_VERSION_1_2;
    /*In JNI1.2 and Java2 SDK 1.4 the JNI_GetDefaultJavaVMInitArgs method call is not required.*/
    //JNI_GetDefaultJavaVMInitArgs( & vm_args);
    res = JNI_CreateJavaVM( &jvm, (void**)&env, &vm_args);
    if (res < 0) {
        fprintf(stderr, "Can't create Java VM\n Error is :%ld\n ", res);
        exit(1);
    iJvmInitialized = 1;
} hi
Check the lib path
May be u have not included : at the end of the lib
path that u have added
THis was the mistake that i did
kabilesh

Create class in java. package

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