How to cast an object to a class known only at runtime

I have a HashMap with key as a class name and value as the instance of that class. When I do a 'get' on it with the class name as the key, what I get back is a generic java.lang.Object. I want to cast this generic object to the class to which it belongs. But I don't know the class at compile time. It would be available only at runtime. And I need to invoke methods on the instance of this specifc class.
I'm not aware of the ways to do it. Could anybody suggest/guide me how to do it? I would really appreciate.
Thanks a lot in advance.

Thanks all for the prompt replies. I am using
reflection and so a generic object is fine, I guess.
But a general question (curiosity) specific to your
comment - extraordinarily generic...
I understand there's definitely some overhead of
reflection. So is it advisable to go for interface
instead of reflection?
Thanks.Arguments for interfaces rather than reflection...
Major benefit at run-time:
Invoking a method using reflection takes more than 20 times as long without using a JIT compiler (using the -Xint option of Java 1.3.0 on WinNT)... Unable to tell with the JIT compiler, since the method used for testing was simple enough to inline - which resulted in an unrealistic 100x speed difference.
The above tests do not include the overhead of exception handling, nor for locating the method to be executed - ie, in both the simple method invocation and reflective method invocations, the exact method was known at compile time and so there is no "locative" logic in these timings.
Major benefit at compile-time:
Compile-time type safety! If you are looking for a method doSomething, and you typo it to doSoemthing, if you are using direct method invocation this will be identified at compile time. If you are using reflection, it will compile successfully and throw a MethodNotFoundException at run time.
Similarly, direct method invocation offers compile-time checking of arguments, result types and expected exceptions, which all need to be dealt with at runtime if using reflection.
Personal and professional recommendation:
If there is any common theme to the objects you're storing in your hashtable, wrap that into an interface that defines a clear way to access expected functionality. This leaves implementations of the interface (The objects you will store in the hashtable) to map the interface methods to the required functionality implementation, in whatever manner they deem appropriate (Hopefully efficiently :-)
If this is feasible, you will find it will produce a result that performs better and is more maintainable. If the interface is designed well, it should also be just as extensible as if you used reflection.

Similar Messages

Creating an array of objects of a class known ONLY at RUNTIME

I have a method in a class which expects an array of objects of particular type (say A) as its only argument. I 'invoke' this method using reflection. I have the instances of the class A stored in a Vector. When I do 'toArray' on this vector, what I get back is an array of Objects and not an array of objects of A. I assign this array to the zeroth element of another Object array and pass that array as a second argument to the 'invoke' method. Of course, it throws an Exception saying - argument types mismatch. Because I am sending an array of Objects to a method expecting an array of objects of A. My problem is I don't know A until runtime. So I have to handle whatever I am getting back after doing 'toArray' on a vector as a Generic Object. I know there's another version of 'toArray' in the Vector class. But it's API documentation didn't help a lot.
Can anybody please help me solve this problem? Any sort of hints/code snippet would be of great help.
Does the above description makes any sense? If not, please let me know. I would try to illustrate it with a code sample.
Thanks a lot in advance.

Sorry, for the small typo. It is -
clazz[] arr = (clazz [])java.lang.reflect.Array.newInstance(clazz, n);
instead
Thanks for the reply. I could do this. But I am
getting a handle to the method to be 'invoke'd by
looking at the types of the parameters its
expecting(getParameterTypes). So I can't change it to
accept an array of Generic Objects.
I looked at the java.lang.reflect.Array class to do
this. This is what I am trying to do-
String variableName is an input coming into my
program.
n is the size of the array I'm trying to create.
Class clazz = Class.forName(variableName);
clazz[] arr = (clazz
[])java.lang.reflect.newInstance(clazz, n);
According to Reflection API, it should work, right?
But compiler yells at me saying 'class clazz not
found'.
Any suggestions/hints/help?
Thanks, again.

How to cast an Object into a specific type (Integer/String) at runtime

Problem:
How to cast an Object into a specific type (Integer/String) at runtime, where type is not known at compile time.
Example:
public class TestCode {
     public static Object func1()
Integer i = new Integer(10); //or String str = new String("abc");
Object temp= i; //or Object temp= str;
return temp;
     public static void func2(Integer param1)
          //Performing some stuff
     public static void main(String args[])
     Object obj = func1();
//cast obj into Integer at run time
     func2(Integer);
Description:
In example, func1() will be called first which will return an object. Returned object refer to an Integer object or an String object. Now at run time, I want to cast this object to the class its referring to (Integer or String).
For e.g., if returned object is referring to Integer then cast that object into Integer and call func2() by passing Integer object.

GDS123 wrote:
Problem:
How to cast an Object into a specific type (Integer/String) at runtime, where type is not known at compile time.
There is only one way to have an object of an unknown type at compile time. That is to create the object's class at runtime using a classloader. Typically a URLClassloader.
Look into
Class.ForName(String)

How to create an object of a class?

plz read the question carefully ..
how to create the object of a class by giving the class name as an String
suppose i have a java file name:" java1.java ".
so now how to create an object of this class "java1"by passing a string "java1"..

kajbj wrote:
rajeev-usendi wrote:
thanks but still i have problem..
i have created the object but now i m unable to do anything with that created object..
i have coded like this..
Object o= Class.forName("java1").new Instance();
after this i m unable to do anything with the object 'o'..So why did you create the instance? You can also get all methods using reflection, but that is probably not what you want to do. You should instead let the class implement an interface and cast the created object into that interface ans call the methods that you want to call.
KajI agree with Kaj. If you need to use a class that's unavailable at compile time, you should create an appropriate interface by which to refer to the class and then you create instances reflectively and access them normally via their interface (which is called reflective instantiation with interface access)

How to cast to a user given class..

Hi all....
Can u help me to create a generic method which take a class name
as String and cast one object to this class type and return.
Note :class name is provided as String.

Hi Suresh.... you can't do such a thing.
public class Foo {
     public static Object castTo(Object obj, String className) throws Exception {
          Class clazz     = Class.forName(className);
          return clazz.cast(obj);
     public static void main(String[] args) throws Exception {
          Test2 s = new Test2();
          Object o = castTo(s, "Test1");
          System.out.println(o);
class Test1 {
     public String toString(){
          return this.getClass().toString();
class Test2 extends Test1 { }

How to cast an object in JSF?

I am working on a travel application. A user can have several bookings and a booking can have several components. A component can be either air or hotel. I want to list the user's bookings on the client using JSF datatable.
<h:dataTable var="component" value="#{booking.components}">
Now depending upon the class of component I need to present different information.
My question is how to cast the variable in JSF ?
Thanks

You can use the String value of Object#getClass()#getName() to lookup the classname and evaluate it in the 'rendered' attribute.
Basic example:
package mypackage;
public class Animal {}
package mypackage;
public class Cat extends Animal {}
package mypackage;
public class Dog extends Animal {}
package mypackage;
public class Fish extends Animal {}MyBeanpublic List<Animal> getList() {
    List<Animal> animals = new ArrayList<Animal>();
    animals.add(new Dog());
    animals.add(new Cat());
    animals.add(new Fish());
    return animals;
}JSF<h:dataTable value="#{myBean.list}" var="item">
    <h:column>
        <h:outputText value="It's a Cat" rendered="#{item.class.name == 'mypackage.Cat'}" />
        <h:outputText value="It's a Dog" rendered="#{item.class.name == 'mypackage.Dog'}" />
        <h:outputText value="It's a Fish" rendered="#{item.class.name == 'mypackage.Fish'}" />
    </h:column>
</h:dataTable>As far there is no way to cast objects in JSF.
Edit
If you find it useful, move the classname request to the superclass:
public class Animal {
    public String getType() {
        String className = getClass().getName();
        return className.substring(className.lastIndexOf('.') + 1);
}Which makes life easier without struggling with package names:<h:outputText value="It's a Cat" rendered="#{item.type == 'Cat'}" />
<h:outputText value="It's a Dog" rendered="#{item.type == 'Dog'}" />
<h:outputText value="It's a Fish" rendered="#{item.type == 'Fish'}" />Message was edited by:
BalusC

How do i create objects of ordinary Classes from a javabean

I want to create a class Person below that I want to create an object from in my javabeans.
Look below Person class definition for continuation.
package data;
public class Person
private String name;
public Person()
name = "No name yet.";
public Person(String initialName)
name = initialName;
public void setName(String newName)
name = newName;
public String getName()
return name;
public void writeOutput()
System.out.println("Name: " + name);
public boolean sameName(Person otherPerson)
return (this.name.equalsIgnoreCase(otherPerson.name));
I run this bean class in the WEB-INF/classes/data folder creating a Person object in the deal() method below
When I compile the class it seems to fail. It does not recognise the Person class. Can you help me with a description of what to do to call
ordinary class objects from javabean class definitions.
What directories should the simple classes be put and what should I include in the javabean to be able to access them?
package data;
import java.sql.*;
import data.*;
public class Bean
{ private Connection databaseConnection ;
// private Person p;
public Bean()
super();
public boolean connect() throws ClassNotFoundException, SQLException
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
String sourceURL = "jdbc:odbc:robjsp";
databaseConnection = DriverManager.getConnection(sourceURL);
return true;
public ResultSet execquery(String restrict) throws SQLException
Statement statement = databaseConnection.createStatement();
String full = "SELECT customerid,CITY,Address from customers " + restrict;
ResultSet authorNames = statement.executeQuery(full);
return (authorNames ==null ) ? null : authorNames;
public String deal() throws SQLException
{ Person p = new Person();
p.setName("Roberto");
return p.getName();
}

There is no "Copy File" function in Lightroom.
Lightroom was designed to eliminate the need to make duplicate copies of files. The organizational tools in Lightroom allow you to have one file categorized in many ways, you can assign multiple keywords to the photos (for example: Winery, Finger Lakes, Fall Foliage, Jessica). Similarly, you can have a file categorized in multiple Lightroom collections at the same time, all without making a copy of the photo. The benefit of this is that you don't need to make multiple copies of each photo, one copy suffices, and thus disk space is saved; and furthermore if you should edit a photo or add metadata, you only need to do this once, and the photo's appearance, or the photo's metadata is changed, and visible to you no matter how you choose to access the photo (pick any keyword or any collection and you will see the change)

How to create an object of inner class

hi i don't know how to create an object of an inner class..
i got something like
class Abc{
private class Abcd {
like this and i want to create an object of Abcd so that i can use some of method
there..
i think i should create the outter class object first right? but not sure
the syntax.. i tried something like
Abc.Abcd justTry = new Abc.Abcd()
something like this..but not work..
help me plz. ...

If the nested class (that's not technically an inner
class you have there) is not static, then you can't
refer to it with OuterClassName.InnerClassName any
more than you can refer to any other member--method
or variable--with ClassName.staticMember.
You need an instance.
It's been a while since I've created an instance of a
non-static nested class from outside that clsas, but
I think it's something like this: Outer outer = new Outer();
outer.Inner inner = new outer.Inner();
Actually, I think it is this:
Outer outer = new Outer();
outer.Inner inner = outer.new Inner();Can't test it now though, gotta go to Taco John's for TACO TUESDAY!!!!
Gotta love them crunchy shell bean tacos!!!

How to make an object of inner class and use it ?

Hi tecs,
In my JSF application i have a need to make an inner member class in one of my bean class.
How can i make the object of this class?(what should be the entry in faces-config)
And there are text box and check box (in the JSP) associated with the elements of this inner class. What should be the coding in JSP so that elements in the JSP can be linked with the corresponding members of the inner class ?
Plz help.
Thnx in advance.

Hi
I am havin 10 text boxes in my application.
But out of 10 , 3 will be always together(existence of one is not possible without the other two.)
Now i want to create a vector of objects ( here object will consist of the value corresponding to these three boxes),there can be many elements in this vector.
So i m thinking to make an inner class which have three String variables corresponding to these text boxes that exists together.
What can b done ?

Unable to Cast a Object into Typed Class

Hi, I am not able to cast a simple object in typed class.
I have a class ItemVO.as
package
    public class ItemVO
        public var idData:String;
        public var valData:String;
In application on some action
            var obj:Object = new Object;
            obj['idData']="001";
            obj['valData']="abhinav";
            try{
                var itemVO:ItemVO=ItemVO(obj);
            }catch(e:Error)
                Alert.show(e.message);
I am getting below error at var itemVO:ItemVO=ItemVO(obj)
Error #1034: Type Coercion failed: cannot convert Object@b5c3ad9 to ItemVO.
Where I am doing wrong??
Please help.
Thanks.
Abhinav

You need to do it by hand.
Or make ItemVO able to take an object as constructor argument. Which is again doing it by hand.
public function ItemVO(obj:Object)
    idData = obj.idData;
    valData = obj.valData;
C

How to pass the object of one class to the another class?

Hello All,
My problem is i am sending the object of serializable class from one class to another class but when i collection this class into another it is transfering null to that side even i filled that object into the class before transfer and the point is class is serializable
code is below like
one class contain the code where i collecting the object by calling this function of another class:-
class
lastindex and initIndex is starting and ending range
SentenceStatusImpl tempSS[] = new SentenceStatusImpl[lastIndex-initIndex ];
tempSS[i++] = engineLocal.CallParser(SS[initIndex],g_strUserName,g_strlanguage,g_strDomain);
another class containg code where we transfering the object:-
class
public SentenceStatusImpl CallParser(SentenceStatusImpl senStatus, String strUserName, String strLanguage, String strDomain)
*//here some code in try block*
finally
System.+out+.println("inside finally...........block......"+strfinaloutput.length);
senStatus.setOutputSen(strfinaloutput);//strfinaloutput is stringbuffer array containg sentence
fillSynonymMap(senStatus);
senStatus.setTranslateStatus(*true*);
return senStatus;
Class of which object is serialized name sentenceStatusimpl class:-
public class SentenceStatusImpl implements Serializable
///Added by pavan on 10/06/2008
int strSourceSenNo;
String strSourceSen = new String();
String strTargetSen = new String();
StringBuffer[] stroutputSen = null;
HashMap senHashMap = new HashMap();
HashMap dfaMarkedMap = new HashMap();
boolean bTargetStatus = false;
public SentenceStatusImpl(){
public void setOutputSen(StringBuffer[] outputSen){
stroutputSen = outputSen;
public StringBuffer[] getOutputSen(){
return stroutputSen;
public void setTranslateStatus(*boolean* TargetStatus){
bTargetStatus = TargetStatus;
}//class

ok,
in class one
we are calling one function (name callParser(object of sentenceStatusImpl class,.....argument.) it return object of sentenceStatusImple class containg some extra information ) and we collecting that object into same type of object.
and that sentenceStatusImple classs implements by Serializable
so it some cases it is returning null
if you think it is not proper serialization is please replay me and suggest proper serialization so that my work is to be done properly (without NULL)
hope you understand my problem

How to set a line of table as read only during runtime?

How to set a line (or a cell) of table as read only during runtime?

hi wei
when you create a table keep the readonly property of table as false
you create the columns of table as inputfield.you bind the readonly property of
the inputfield to two context variables
say one for all the columnfields you to want always have as readonly and let this contextattribute of type boolean and let this be attr1
and another for all the columnfields you donot want to be readonly and let this contextattribute of type boolean and let this be attr2
initially set the context attributes attr1 and attr2 as true so the entire table is readonly.
based on the condition you want to check change the attr2 to be false.
if(your condition)
wdcontext.currentcontextelement.setattr2(false);
hope this helps.
regards
saravana

How do i use objects from one class in anohter?

Hey
I have two GUI classes ShowWhiteGUI and BasketGUI and then a control class ShowWhite. The control class calls all the method from anohter class's which the GUI classes are gonna use.
The basis idea with this script is it shall be a very very simpel Shop. Where you can add items to a basket and then show the items in a new window(BasketGUI).
So here is the problem. I cant create an object in both GUI classes, because then im working with two sets of data, right? So how do i do this?
Here is my code:
ShowWhiteGUI
* ShowWhiteGUI.java
* Created on 5. februar 2008, 10:43
package userclasses;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
* @author Lille mus
public class ShowWhiteGUI extends javax.swing.JFrame {
    private BasketGUI basketGUI;
    private ShowWhite control;
    /** Creates new form ShowWhiteGUI */
    public ShowWhiteGUI() {
        basketGUI = new BasketGUI();
        control = new ShowWhite();
        initComponents();
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {
        aboutDialog = new javax.swing.JDialog();
        jLabel1 = new javax.swing.JLabel();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();
        itemIdField = new javax.swing.JTextField();
        productIdLabel = new javax.swing.JLabel();
        numberOfItems = new javax.swing.JLabel();
        productId = new javax.swing.JTextField();
        basketButton = new javax.swing.JButton();
        jLabel2 = new javax.swing.JLabel();
        showBasketButton = new javax.swing.JButton();
        jMenuBar1 = new javax.swing.JMenuBar();
        menu = new javax.swing.JMenu();
        jMenu1 = new javax.swing.JMenu();
        open = new javax.swing.JMenuItem();
        quit = new javax.swing.JMenuItem();
        jMenuItem1 = new javax.swing.JMenuItem();
        jMenu2 = new javax.swing.JMenu();
        help = new javax.swing.JMenuItem();
        about = new javax.swing.JMenuItem();
        javax.swing.GroupLayout aboutDialogLayout = new javax.swing.GroupLayout(aboutDialog.getContentPane());
        aboutDialog.getContentPane().setLayout(aboutDialogLayout);
        aboutDialogLayout.setHorizontalGroup(
            aboutDialogLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 400, Short.MAX_VALUE)
        aboutDialogLayout.setVerticalGroup(
            aboutDialogLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 300, Short.MAX_VALUE)
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Show White's Shop");
        setBackground(new java.awt.Color(0, 102, 255));
        jLabel1.setFont(new java.awt.Font("Baby Kruffy", 0, 36));
        jLabel1.setText("Snow White?s Shop");
        jTextArea1.setColumns(20);
        jTextArea1.setEditable(false);
        jTextArea1.setRows(5);
        jTextArea1.setText(control.getPrintAllStockItems());
        jScrollPane1.setViewportView(jTextArea1);
        productIdLabel.setText("Varenummer:");
        numberOfItems.setText("Antal:");
        basketButton.setText("L?g i kurv");
        basketButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                putInBasket(evt);
        showBasketButton.setText("Vis indk?bskurv");
        showBasketButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                showBasket(evt);
        menu.setLabel("Fil");
        jMenu1.setText("Menu");
        menu.add(jMenu1);
        open.setLabel("?bn");
        open.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                open(evt);
        menu.add(open);
        quit.setLabel("Luk");
        quit.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                quit(evt);
        menu.add(quit);
        jMenuItem1.setLabel("Gem");
        jMenuItem1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                save(evt);
        menu.add(jMenuItem1);
        jMenuBar1.add(menu);
        jMenu2.setLabel("Hj?lp");
        help.setLabel("Hj?lp");
        help.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                help(evt);
        jMenu2.add(help);
        about.setLabel("Om Show White Shop");
        jMenu2.add(about);
        jMenuBar1.add(jMenu2);
        setJMenuBar(jMenuBar1);
        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(37, 37, 37)
                        .addComponent(jLabel1))
                    .addGroup(layout.createSequentialGroup()
                        .addContainerGap()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
                            .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                                .addComponent(productIdLabel)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(itemIdField, javax.swing.GroupLayout.PREFERRED_SIZE, 37, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                .addComponent(numberOfItems))
                            .addComponent(jScrollPane1, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.PREFERRED_SIZE, 184, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                .addGroup(layout.createSequentialGroup()
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                    .addComponent(productId, javax.swing.GroupLayout.PREFERRED_SIZE, 26, javax.swing.GroupLayout.PREFERRED_SIZE)
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 65, Short.MAX_VALUE)
                                    .addComponent(basketButton))
                                .addGroup(layout.createSequentialGroup()
                                    .addGap(31, 31, 31)
                                    .addComponent(jLabel2)))
                            .addGroup(layout.createSequentialGroup()
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(showBasketButton)))))
                .addContainerGap())
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addComponent(jLabel1)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 179, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(jLabel2))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 49, Short.MAX_VALUE)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(productIdLabel)
                            .addComponent(itemIdField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(numberOfItems)
                            .addComponent(productId, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(showBasketButton)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 202, Short.MAX_VALUE)
                        .addComponent(basketButton)))
                .addContainerGap())
        pack();
    }// </editor-fold>
    public void createBasketWindow(){
        basketGUI.setVisible(true);
    private void showBasket(java.awt.event.ActionEvent evt) {
        createBasketWindow();
    private void putInBasket(java.awt.event.ActionEvent evt) {
        Integer itemId = Integer.parseInt(itemIdField.getText());
        String petToAdd = control.getFindItem(itemId);
        System.out.println(petToAdd);
        control.setAddItemToBasket(itemId);
        basketGUI.addPetToBasket(petToAdd);
    private void help(java.awt.event.ActionEvent evt) {
    private void save(java.awt.event.ActionEvent evt) {
        System.out.println("Gemmer fil");
    private void open(java.awt.event.ActionEvent evt) {
        System.out.println("?bn fil");
    private void quit(java.awt.event.ActionEvent evt) {
        System.exit(0);
    public ShowWhite getControl(){
        return control;
     * @param args the command line arguments
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new ShowWhiteGUI().setVisible(true);
    // Variables declaration - do not modify
    private javax.swing.JMenuItem about;
    private javax.swing.JDialog aboutDialog;
    private javax.swing.JButton basketButton;
    private javax.swing.JMenuItem help;
    private javax.swing.JTextField itemIdField;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JMenu jMenu1;
    private javax.swing.JMenu jMenu2;
    private javax.swing.JMenuBar jMenuBar1;
    private javax.swing.JMenuItem jMenuItem1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    private javax.swing.JMenu menu;
    private javax.swing.JLabel numberOfItems;
    private javax.swing.JMenuItem open;
    private javax.swing.JTextField productId;
    private javax.swing.JLabel productIdLabel;
    private javax.swing.JMenuItem quit;
    private javax.swing.JButton showBasketButton;
    // End of variables declaration
}BasketGUI:
* Basket.java
* Created on 5. februar 2008, 15:29
package userclasses;
import javax.swing.JTextArea;
* @author Lille mus
public class BasketGUI extends javax.swing.JFrame {
    private String newline = "\n";
    private InvoiceGUI invoiceGUI;
    /** Creates new form Basket */
    public BasketGUI() {
        initComponents();
        //invoiceGUI = new InvoiceGUI();
    public void addPetToBasket(String pet){
        jTextArea1.append(pet+newline);
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {
        jLabel1 = new javax.swing.JLabel();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();
        jButton1 = new javax.swing.JButton();
        itemIdField = new javax.swing.JTextField();
        jLabel2 = new javax.swing.JLabel();
        removeItemButton = new javax.swing.JButton();
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Indk?bskurv");
        jLabel1.setText("Indk?bskurv");
        jTextArea1.setColumns(20);
        jTextArea1.setRows(5);
        jScrollPane1.setViewportView(jTextArea1);
        jButton1.setText("K?b og print kvittering");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                printInvoice(evt);
        jLabel2.setText("Slet varenr");
        removeItemButton.setText("Slet");
        removeItemButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                removeItemFromBasket(evt);
        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(21, 21, 21)
                        .addComponent(jLabel1))
                    .addGroup(layout.createSequentialGroup()
                        .addContainerGap()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(layout.createSequentialGroup()
                                .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 141, Short.MAX_VALUE)
                                .addComponent(jButton1))
                            .addGroup(layout.createSequentialGroup()
                                .addComponent(jLabel2)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(itemIdField, javax.swing.GroupLayout.PREFERRED_SIZE, 24, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(removeItemButton)))))
                .addContainerGap())
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabel1)
                .addGap(20, 20, 20)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jButton1)
                    .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 125, Short.MAX_VALUE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jLabel2)
                    .addComponent(itemIdField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addComponent(removeItemButton))
                .addContainerGap())
        pack();
    }// </editor-fold>
    private void removeItemFromBasket(java.awt.event.ActionEvent evt) {
        Integer itemId = Integer.parseInt(itemIdField.getText());
    private void printInvoice(java.awt.event.ActionEvent evt) {
        //invoiceGUI.setVisible(true);
    public JTextArea getTextArea(){
        return jTextArea1;
     * @param args the command line arguments
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new BasketGUI().setVisible(true);
    // Variables declaration - do not modify
    private javax.swing.JTextField itemIdField;
    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    private javax.swing.JButton removeItemButton;
    // End of variables declaration
}ShowWhite:
* ShowWhite.java
* Created on 13. februar 2008, 18:15
* To change this template, choose Tools | Template Manager
* and open the template in the editor.
package userclasses;
* @author Lille mus
public class ShowWhite {
    public Basket basket;
    public Stock stock;
    /** Creates a new instance of ShowWhite */
    public ShowWhite() {
        stock = new Stock();
        basket = new Basket();
    public String getFindItem(int itemId){
        String returnItem = stock.findItem(itemId);
        return returnItem;
    public void setAddItemToBasket(int itemId){
        basket.addItemToBasket(itemId);
    public String getPrintAllStockItems(){
        return stock.printAllStockItems();
    public String getShowBasket(){
         return basket.showBasket();
    public void setRemoveItemFromBasket(int itemId){
        basket.removeItemFromBasket(itemId);
}

okay i tried this, but it give me a nullpointerexeption:
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at userclasses.ShowWhiteGUI.initComponents(ShowWhiteGUI.java:75)
at userclasses.ShowWhiteGUI.<init>(ShowWhiteGUI.java:21)
at userclasses.ShowWhite.<init>(ShowWhite.java:26)
at userclasses.Main.<init>(Main.java:16)
at userclasses.Main$1.run(Main.java:31)
ShowWhite
public class ShowWhite {
    public Basket basket;
    public Stock stock;
    private ShowWhiteGUI mainGUI;
    private BasketGUI basketGUI;
    /** Creates a new instance of ShowWhite */
    public ShowWhite() {
        stock = new Stock();
        basket = new Basket();
        mainGUI = new ShowWhiteGUI(this);
        basketGUI = new BasketGUI();
    public String getFindItem(int itemId){
        String returnItem = stock.findItem(itemId);
        return returnItem;
    public void setAddItemToBasket(int itemId){
        basket.addItemToBasket(itemId);
    public String getPrintAllStockItems(){
        return stock.printAllStockItems();
    public String getShowBasket(){
         return basket.showBasket();
    public void setRemoveItemFromBasket(int itemId){
        basket.removeItemFromBasket(itemId);
    public void createMainGUI(){
        mainGUI.setVisible(true);
    public BasketGUI getBasketGUI(){
        return basketGUI;
    public void setAddPetToBasket(String pet){
        basketGUI.addPetToBasket(pet);
}ShowWhiteGUI:
public class ShowWhiteGUI extends javax.swing.JFrame {
    private ShowWhite control;
    /** Creates new form ShowWhiteGUI */
    public ShowWhiteGUI(ShowWhite control) {
        initComponents();
        this.control = control;
    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {
        aboutDialog = new javax.swing.JDialog();
        jLabel1 = new javax.swing.JLabel();
        jScrollPane1 = new javax.swing.JScrollPane();
        jTextArea1 = new javax.swing.JTextArea();
        itemIdField = new javax.swing.JTextField();
        productIdLabel = new javax.swing.JLabel();
        numberOfItems = new javax.swing.JLabel();
        productId = new javax.swing.JTextField();
        basketButton = new javax.swing.JButton();
        jLabel2 = new javax.swing.JLabel();
        showBasketButton = new javax.swing.JButton();
        jMenuBar1 = new javax.swing.JMenuBar();
        menu = new javax.swing.JMenu();
        jMenu1 = new javax.swing.JMenu();
        open = new javax.swing.JMenuItem();
        quit = new javax.swing.JMenuItem();
        jMenuItem1 = new javax.swing.JMenuItem();
        jMenu2 = new javax.swing.JMenu();
        help = new javax.swing.JMenuItem();
        about = new javax.swing.JMenuItem();
        javax.swing.GroupLayout aboutDialogLayout = new javax.swing.GroupLayout(aboutDialog.getContentPane());
        aboutDialog.getContentPane().setLayout(aboutDialogLayout);
        aboutDialogLayout.setHorizontalGroup(
            aboutDialogLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 400, Short.MAX_VALUE)
        aboutDialogLayout.setVerticalGroup(
            aboutDialogLayout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 300, Short.MAX_VALUE)
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Show White's Shop");
        setBackground(new java.awt.Color(0, 102, 255));
        jLabel1.setFont(new java.awt.Font("Baby Kruffy", 0, 36));
        jLabel1.setText("Snow White?s Shop");
        jTextArea1.setColumns(20);
        jTextArea1.setEditable(false);
        jTextArea1.setRows(5);
        jTextArea1.setText(control.getPrintAllStockItems());
        jScrollPane1.setViewportView(jTextArea1);
        productIdLabel.setText("Varenummer:");
        numberOfItems.setText("Antal:");
        basketButton.setText("L?g i kurv");
        basketButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                putInBasket(evt);
        showBasketButton.setText("Vis indk?bskurv");
        showBasketButton.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                showBasket(evt);
        menu.setLabel("Fil");
        jMenu1.setText("Menu");
        menu.add(jMenu1);
        open.setLabel("?bn");
        open.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                open(evt);
        menu.add(open);
        quit.setLabel("Luk");
        quit.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                quit(evt);
        menu.add(quit);
        jMenuItem1.setLabel("Gem");
        jMenuItem1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                save(evt);
        menu.add(jMenuItem1);
        jMenuBar1.add(menu);
        jMenu2.setLabel("Hj?lp");
        help.setLabel("Hj?lp");
        help.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                help(evt);
        jMenu2.add(help);
        about.setLabel("Om Show White Shop");
        jMenu2.add(about);
        jMenuBar1.add(jMenu2);
        setJMenuBar(jMenuBar1);
        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addGap(37, 37, 37)
                        .addComponent(jLabel1))
                    .addGroup(layout.createSequentialGroup()
                        .addContainerGap()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING, false)
                            .addGroup(javax.swing.GroupLayout.Alignment.LEADING, layout.createSequentialGroup()
                                .addComponent(productIdLabel)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(itemIdField, javax.swing.GroupLayout.PREFERRED_SIZE, 37, javax.swing.GroupLayout.PREFERRED_SIZE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                .addComponent(numberOfItems))
                            .addComponent(jScrollPane1, javax.swing.GroupLayout.Alignment.LEADING, javax.swing.GroupLayout.PREFERRED_SIZE, 184, javax.swing.GroupLayout.PREFERRED_SIZE))
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                .addGroup(layout.createSequentialGroup()
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                    .addComponent(productId, javax.swing.GroupLayout.PREFERRED_SIZE, 26, javax.swing.GroupLayout.PREFERRED_SIZE)
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 65, Short.MAX_VALUE)
                                    .addComponent(basketButton))
                                .addGroup(layout.createSequentialGroup()
                                    .addGap(31, 31, 31)
                                    .addComponent(jLabel2)))
                            .addGroup(layout.createSequentialGroup()
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(showBasketButton)))))
                .addContainerGap())
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addComponent(jLabel1)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.TRAILING)
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jScrollPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 179, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(jLabel2))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 49, Short.MAX_VALUE)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                            .addComponent(productIdLabel)
                            .addComponent(itemIdField, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(numberOfItems)
                            .addComponent(productId, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)))
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(showBasketButton)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 202, Short.MAX_VALUE)
                        .addComponent(basketButton)))
                .addContainerGap())
        pack();
    }// </editor-fold>
    public void createBasketWindow(){
        control.getBasketGUI().setVisible(true);
    private void showBasket(java.awt.event.ActionEvent evt) {
        createBasketWindow();
    private void putInBasket(java.awt.event.ActionEvent evt) {
        Integer itemId = Integer.parseInt(itemIdField.getText());
        String petToAdd = control.getFindItem(itemId);
        System.out.println(petToAdd);
        control.setAddItemToBasket(itemId);
        control.setAddPetToBasket(petToAdd);
    private void help(java.awt.event.ActionEvent evt) {
    private void save(java.awt.event.ActionEvent evt) {
        System.out.println("Gemmer fil");
    private void open(java.awt.event.ActionEvent evt) {
        System.out.println("?bn fil");
    private void quit(java.awt.event.ActionEvent evt) {
        System.exit(0);
    public ShowWhite getControl(){
        return control;
    // Variables declaration - do not modify
    private javax.swing.JMenuItem about;
    private javax.swing.JDialog aboutDialog;
    private javax.swing.JButton basketButton;
    private javax.swing.JMenuItem help;
    private javax.swing.JTextField itemIdField;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JMenu jMenu1;
    private javax.swing.JMenu jMenu2;
    private javax.swing.JMenuBar jMenuBar1;
    private javax.swing.JMenuItem jMenuItem1;
    private javax.swing.JScrollPane jScrollPane1;
    private javax.swing.JTextArea jTextArea1;
    private javax.swing.JMenu menu;
    private javax.swing.JLabel numberOfItems;
    private javax.swing.JMenuItem open;
    private javax.swing.JTextField productId;
    private javax.swing.JLabel productIdLabel;
    private javax.swing.JMenuItem quit;
    private javax.swing.JButton showBasketButton;
    // End of variables declaration
}

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