Public class or just simply class?

As I continue my reading into various books there are some books which will have you add the access modifier public in front of your classname. Other books will just have you leave it out. I tried out a simple program that declared a class in a separate file and then the second file was the main class file with the main method.
It didn't matter whether or not I removed the keyword public in front of the name of my class in the first file. The program compiled and ran just fine. So I'm doing some looking on the web trying to understand what the word public means when it's placed in front of your classname.
According to Sun:
A class may be declared with the modifier public, in which case that class is visible to all classes everywhere. If a class has no modifier (the default, also known as package-private), it is visible only within its own package (packages are named groups of related classes?you will learn about them in a later lesson.)
I picked this up from some other source:
Java provides a default specifier which is used when no access modifier is present. Any class, field, method or constructor that has no declared access modifier is accessible only by classes in the same package.
So if I understand this correctly if I place the word public in front of my classname my class is visible to all classes and all packages?
And if I don't place the word public in front of my classname then the class that I defined is only accessible only by other classes in the same package whatever that package happens to be?
So if I wrote this:
public class MyVehicle
}Then if I imported a package called import.java.GiveMeSomePaintingTools;
Then the classes contained in the GiveMeSomePaintingTools would have access to the MyVehicle class that I made?
And if I just wrote this:
class MyVehicle
}Then the classes in the package GiveMeSomePaintingTools would not have access to the class I made?
That's what I gather...
Edited by: 357mag on Jun 3, 2010 5:53 AM

357mag wrote:
Then the classes in the package GiveMeSomePaintingTools would not have access to the class I made?The clue as to what access modifier to use for a class will often be in its name. Generally you write a class to do something. If what it does is something you want the whole world to be able to do, then use public; if it is only used by other classes of a package you've written, then use the default. The third one is protected: you use this when the class needs to be visible within a hierarchy (especially one that can be extended by anyone).
As an example: [java.math.BigInteger|http://java.sun.com/javase/6/docs/api/java/math/BigInteger.html] is a class that allows you to store arbitrarily large integer values. Sun clearly felt that this was useful enough to allow anyone to have access to it, so it is public. However, it is defined as immutable: ie, once you've created a BigInteger object, you cannot change its value. This is not optimal for arithmetic, where you may have several operations to perform to get a result: If each of them is forced to create a new object, you could waste a lot of time (and space).
So the designers created a class called MutableBigInteger which is used by the BigInteger class (and also by BigDecimal) to hold interim values for calculations. Since this class is only used by those classes, it is defined with the default modifier (which is why you've never seen it).
HIH
Winston

Similar Messages

How to get fully qualified name for a class with just the class name

I want to get the fully qualified name of the class at runtime. The only piece of information which I have is the class name.
I want to create a runtime instance of a class with the class name [Just the class name].
Is there is any way to achieve this using ClassLoader?
Could anyone suggest me an idea?
Cheers,
Vinn.

Nope. If you are given "List", will you decide that means "java.util.List" or "java.awt.List"? Of course you could prompt the user to make the decision for you, I suppose. But using a class loader isn't going to make the task any easier.

How to access a method of a class which just known class name as String

Hi,
Now I have several class and I want to access the method of these class. But what I have is a String which contain the complete name of the class.
For example, I have two class name class1and class2, there are method getValue in each class. Now I have a String containing one class name of these two class. I want to access the method and get the return value.
How could I do?
With Class.forName().newInstance I can get a Object. but it doesn't help to access and execute the method I want .
Could anybody help me?
Thanks

Or, if Class1 and Class2 have a common parent class or interface (and they should if you're handling them the same way in the same codepath)...Class c = Class.forName("ClassName");
Object o = c.newInstance(); // assumes there's a public no-arg constructor
ParentClassOrInterface pcoi = (ParentClassOrInterface)o;
Something result = pcoi.someMethod(); Or, if you're on 5.0, I think generics let you do it this way: Class<ParentClassOrInterface> c = Class.forName("ClassName");
// or maybe
Class<C extends ParentClassOrInterface> c = Class.forName("ClassName");
ParentClassOrInterface pcoi = c.newInstance();
Something result = pcoi.someMethod();

Accessing a private variable from a public method of the same class

can anyone please tell me how to access a private variable, declared in a private method from a public method of the same class?
here is the code, i'm trying to get the variable int[][][] grids.
public static int[][] generateS(boolean[][] constraints)
private static int[][][] sudokuGrids()
    int[][][] grids; // array of arrays!
    grids = new int[][][]
    {

Are you sure that you want to have everything static here? You're possibly throwing away all the object-oriented goodness that java has to offer.
Anyway, it seems to me that you can't get to that variable because it is buried within a method -- think scoping rules. I think that if you want to get at that variable your program design may be under the weather and may benefit from a significant refactoring in an OOP-manner.
If you need more specific help, then ask away, but give us more information please about what you are trying to accomplish here and how you want to do this. Good luck.
Pete
Edited by: petes1234 on Nov 16, 2007 7:51 PM

Problem in generic value copier class / reflection and generic classes

Hello experts,
I try to archive the following and am struggling for quite some time now. Can someone please give an assessment if this is possible:
I am trying to write a generic data copy method. It searches for all (parameterless) getter methods in the source object that have a corresponding setter method (with same name but prefixed by "set" instead of "get" and with exactly one parameter) in the destination object.
For each pair I found I do the following: If the param of the setter type (T2) is assignable from the return type of the getter (T1), I just assign the value. If the types are not compatible, I want to instantiate a new instance of T2, assign it via the setter, and invoke copyData recursively on the object I get from the getter (as source) and the newly created instance (as destination). The assumption is here, that the occurring source and destination objects are incompatible but have matching getter and setter names and at the leaves of the object tree, the types of the getters and setters are compatible so that the recursion ends.
The core of the problem I am struggling with is the step where I instantiate the new destination object. If T2 is a non-generic type, this is straightforward. However, imagine T1 and T2 are parametrized collections: T1 is List<T3> and T2 is List<T4>. Then I need special handling of the collection. I can easily iterate over the elements of the source List and get the types of the elements, but I can not instantiate only a generic version of the destinatino List. Further I cannot create elements of T4 and add it to the list of T2 and go into recursion, since the information that the inner type of the destination list is T4 is not available at run-time.
public class Source {
   T1 getA();
   setA(T1 x);
public class Dest {
   T2 getA();
   setA(T2 x);
public class BeanDataCopier {
   public static void copyData(Object source, Object destination) {
      for (Method getterMethod : sourceGetterMethods) {
         ... // find matching getter and setter names
         Class sourceParamT = [class of return value of the getter];
         Class destParamT = [class of single param of the setter];
         // special handling for collections - I could use some help here
         // if types are not compatible
         Object destParam = destination.getClass().newInstance();
         Object sourceParam = source.[invoke getter method];
         copyData(sourceParam, destParam);
// usage of the method
Souce s = new Source(); // this is an example, I do not know the type of s at copying time
Dest d = new Dest(); // the same is true for d
// initialize s in a complicated way (actually JAX-B does this)
// copy values of s to d
BeanDataCopier.copyData(s, d);
// now d should have copied values from s Can you provide me with any alternative approaches to implement this "duck typing" behaviour on copying properties?
Best regards,
Patrik
PS: You might have guessed my overall use case: I am sending an object tree over a web service. On the server side, the web service operation has a deeply nested object structure as the return type. On the client side, these resulting object tree has instances not of the original classes, but of client classes generated by axis. The original and generated classes are of different types but have the identically named getter and setter methods (which again have incompatible parameter types that however have consistent names). On the client side, I want to simply create an object of the original class and have the values of the client object (including the whole object tree) copied into it.
Edited by: Patrik_Spiess on Sep 3, 2008 5:09 AM

As I understand your use case this is already supported by Axis with beanMapping [http://ws.apache.org/axis/java/user-guide.html#EncodingYourBeansTheBeanSerializer]
- Roy

Need help with custom event from Main class to an unrelated class.

Hey guys,
I'm new to Flash and not great with OOP. I've made it pretty far with google and lurking, but I've been pulling my hair out on this problem for a day and everything I try throws an error or simply doesn't hit the listener.
I'm trying to get my Main class to send a custom event to an unrelated class called BigIcon. The rest of the code works fine, it's just the addEventListener and dispatchEvent that isn't working.
I've put in the relevant code in below. Let me know if anything else is needed to troubleshoot. Thank you!
Main.as
package
    import flash.display.MovieClip;
    import flash.events.MouseEvent;
    public class Main extends MovieClip
        var iconLayer_mc:MovieClip = new MovieClip();
        public function Main()
            Spin_btn.addEventListener(MouseEvent.CLICK,fl_MouseClickHandler);
            addChildAt(iconLayer_mc,0);
            placeIcons();
        function placeIcons():void
            var i:int;
            var j:int;
            for (i = 0; i < 4; i++)
                for (j = 0; j < 5; j++)
                    //iconString_array has the names of illustrator objects that have been converted to MovieClips and are in the library.
                    var placedIcon_mc:BigIcon = new BigIcon(iconString_array[i][j],i,j);
                    iconLayer_mc.addChild(placedIcon_mc);
        function fl_MouseClickHandler(event:MouseEvent):void
            dispatchEvent(new Event("twitchupEvent",true));
BigIcon.as
package
    import flash.display.MovieClip;
    import flash.events.Event;
    import flash.utils.getDefinitionByName;
    public class BigIcon extends MovieClip
        private var iconImage_str:String;
        private var iconRow_int:int;
        private var iconColumn_int:int;
        public function BigIcon(iconImage_arg:String, iconRow_arg:int, iconColumn_arg:int)
            iconImage_str = iconImage_arg;
            iconRow_int = iconRow_arg;
            iconColumn_int = iconColumn_arg;
            this.addEventListener(Event.ADDED_TO_STAGE, Setup);
        function Setup(e:Event)
            this.y = iconRow_int;
            this.x = iconColumn_int;
            var ClassReference:Class = getDefinitionByName(iconImage_str) as Class;
            var thisIcon_mc:MovieClip = new ClassReference;
            this.addChild(thisIcon_mc);
            addEventListener("twitchupEvent", twitchUp);
        function twitchUp(e:Event)
            this.y += 10;

Ned Murphy wrote:
You should be getting an error for the Main.as class due to missing a line to import the Event class...
import flash.events.Event;
My apologies, I should attempt to compile my example code before I ask for help...
Alright, this compiles, gives me no errors, shows my 'book' and 'flowers' icons perfectly when ran, and prints 'addEventListener' to the output window as expected. I get no errors when I press the button, 'dispatchEvent' is output (good), but the 'twitchUp' function is never called and 'EventTriggered' is never output.
How do I get the 'twitchUp' event to trigger?
Main.as
package
    import flash.display.MovieClip;
    import flash.events.MouseEvent;
    import flash.events.*;
    public class Main extends MovieClip
        var iconLayer_mc:MovieClip = new MovieClip();
        var iconString_array:Array = new Array(2);
        public function Main()
            Spin_btn.addEventListener(MouseEvent.CLICK,fl_MouseClickHandler);
            addChildAt(iconLayer_mc,0);
            buildStringArray();
            placeIcons();
        function buildStringArray():void
            var i:int;
            var j:int;
            for (i = 0; i < 2; i++)
                iconString_array[i] = new Array(3);
                for (j = 0; j < 3; j++)
                    if (Math.random() > .5)
                        //'flowers' is the name of an illustrator object that has been converted to a MovieClip and is in the library
                        iconString_array[i][j] = "flowers";
                    else
                        //'book' is the name of an illustrator object that has been converted to a MovieClip and is in the library
                        iconString_array[i][j] = "book";
        function placeIcons():void
            var i:int;
            var j:int;
            for (i = 0; i < 2; i++)
                for (j = 0; j < 3; j++)
                    //iconString_array has the names of illustrator objects that have been converted to MovieClips and are in the library.
                    var placedIcon_mc:BigIcon = new BigIcon(iconString_array[i][j],i*50,j*50);
                    iconLayer_mc.addChild(placedIcon_mc);
        function fl_MouseClickHandler(event:MouseEvent):void
            dispatchEvent(new Event("twitchupEvent",true));
            trace("dispatchEvent");
BigIcon.as
package
    import flash.display.MovieClip;
    import flash.events.*;
    import flash.utils.getDefinitionByName;
    public class BigIcon extends MovieClip
        private var iconImage_str:String;
        private var iconRow_int:int;
        private var iconColumn_int:int;
        public function BigIcon(iconImage_arg:String, iconRow_arg:int, iconColumn_arg:int)
            iconImage_str = iconImage_arg;
            iconRow_int = iconRow_arg;
            iconColumn_int = iconColumn_arg;
            this.addEventListener(Event.ADDED_TO_STAGE, Setup);
        function Setup(e:Event)
            this.y = iconRow_int;
            this.x = iconColumn_int;
            var ClassReference:Class = getDefinitionByName(iconImage_str) as Class;
            var thisIcon_mc:MovieClip = new ClassReference;
            this.addChild(thisIcon_mc);
            addEventListener("twitchupEvent", twitchUp);
            trace("addEventListener");
        function twitchUp(e:Event)
            this.y += 10;
            trace("EventTriggered");
Output:
[SWF] Untitled-1.swf - 40457 bytes after decompression
addEventListener
addEventListener
addEventListener
addEventListener
addEventListener
addEventListener
dispatchEvent
[UnloadSWF] Untitled-1.swf
Test Movie terminated.

[Help] Using a class at the other class

hi guys, i'm still new to java. So that i tried to learn by myself.
i got 2 class: 'Person.java' and 'Ex1.java'
basically, Person just a class for making an object of Person. and the main function is made at Ex1.java.
my problem is: i made 2 Person objects (p1 and p2). then i tried to initialise them in 2 ways (using default constructor and user-defined constructor). Why when i print 'em (p1.print() and p2.print()), it printed p1 attributes only. I tried many ways to do this, but can't find the way out. pls help me...
* Person.java *
public class Person {
     // attributes
     private static String name;
     private static int age;
     // constructor
     public Person() {
          name = "";
          age = -1;
     public Person(String n, int a) {
          name = n;
          age = a;
     // mutator
     public static void setName( String n ) { name = n; }
     public static void setAge( int a) { age = a; }
     // other methods
     public static void print() {
          System.out.println( name + " (" + age + " years old)" );
* Ex1.java *
public class Ex1{
     private static Person p1;
     private static Person p2;
     public static void main(String args[]) {
          p1 = new Person();
          p2 = new Person("Jessica", 25);
          p1.setName("Antonio");
          p1.setAge(20);
          p1.print();
          p2.print();
}

Change
public class Person {
     // attributes
     private static String name;
     private static int age;
to
public class Person {
     // attributes
     private String name;
     private int age;
You're using incorrectly static for object attributes:)

Calling a method from an abstract class in a seperate class

I am trying to call the getID() method from the Chat class in the getIDs() method in the Outputter class. I would usually instantiate with a normal class but I know you cant instantiate the method when using abstract classes. I've been going over and over my theory and have just become more confused??
Package Chatroom
public abstract class Chat
   private String id;
   public String getID()
      return id;
   protected void setId(String s)
      id = s;
   public abstract void sendMessageToUser(String msg);
Package Chatroom
public class Outputter
public String[] getIDs()
     // This is where I get confused. I know you can't instantiate the object like:
        Chat users=new Chat();
        users.getID();
I have the two classes in the package and you need to that to be able to use a class' methods in another class.
Please help me :(

I have just looked over my program and realised my class names are not the most discriptive, so I have renamed them to give you a clearer picture.
package Chatroom
public abstract class Chatter
private String id;
public String getID()
return id;
protected void setId(String s)
id = s;
I am trying to slowly build a chatroom on my own. The Chatter class is a class that will be used to represent a single logged in user and the user is given an ID when he logs in through the setId and getID() methods.
package Chatroom;
import java.util.Vector;
public class Broadcaster
private Vector<Chatter> chatters = new Vector<Chatter>();
public String[] getIDs()
// code here
The Broadcaster class will keep a list of all logged-in users keeps a list of all the chats representing logged-in users, which it stores in a Vector.I am trying to use the getIDs() method to return an array of Strings comprising the IDs of all logged-in users, which is why im trying to use the getID() method from the Chat class.
I apologise if I come across as clueless, it's just I have been going through books for about 4 hours now and I have just totally lossed all my bearings

How to override a method in an inner class of the super class

I have a rather horribly written class, which I need to adapt. I could simply do this if I could override a method in one of it's inner classes. My plan then was to extend the original class, and override the method in question. But here I am struggling.
The code below is representative of my situation.
public class ClassA
   ValueChecks vc = null;
   /** Creates a new instance of Main */
   public ClassA()
      System.out.println("ClassA Constructor");
      vc = new ValueChecks();
      vc.checkMaximum();
     // I want this to call the overridden method, but it does not, it seems to call
     // the method in this class. probably because vc belongs to this class
      this.vc.checkMinimum();
      this.myMethod();
   protected void myMethod()
      System.out.println("myMethod(SUPER)");
   protected class ValueChecks
      protected boolean checkMinimum()
         System.out.println("ValueChecks.checkMinimum (SUPER)");
         return true;
      protected boolean checkMaximum()
         return false;
}I have extended ClassA, call it ClassASub, and it is this Class which I instantiate. The constructor in ClassASub obviously calls the constructor in ClassA. I want to override the checkMinimum() method in ValueChecks, but the above code always calls the method in ClassA. The ClassASub code looks like this
public class ClassASub extends ClassA
   public ClassAInner cias;
   /** Creates a new instance of Main */
   public ClassASub()
      System.out.println("ClassASub Constructor");
   protected void myMethod()
      System.out.println("myMethod(SUB)");
   protected class ValueChecks extends ClassA.ValueChecks
      protected boolean checkMinimum()
         System.out.println("ValueChecks.checkMinimum (SUB)");
         return true;
}The method myMethod seems to be suitably overridden, but I cannot override the checkMinimum() method.
I think this is a stupid problem to do with how the ValueChecks class is instantiated. I think I need to create an instance of ValueChecks in ClassASub, and pass a reference to it into ClassA. But this will upset the way ClassA works. Could somebody enlighten me please.

vc = new ValueChecks();vc is a ValueChecks object. No matter whether you subclass ValueChecks or not, vc is always of this type, per this line of code.
// I want this to call the overridden method, but it does not, it seems to > call
// the method in this class. probably because vc belongs to this class
this.vc.checkMinimum();No, it's because again vc references a ValueChecks object, because it was created as such.
And when I say ValueChecks, I mean the original class, not the one you tried to create by the same name, attempting to override the original.

How to access class variables in anonymous class??.

I have a boolean class level variable. Fom a button action , this boolean will set to true and then it used in anonymous class. In anonymous class, I am getting default value instead of true. Could u anyone help in this plzzz.

first of all, you don't want parent because that is something that Containers use to remember their containment hierarchy. you are thinking of super which is also incorrect, because that has to do with inheritance.
the problem here is a scoping problem. you generally would use final if you were accessing variables in an anonymous class that are in the local scope. in this case, you just need to create some test code and play with it. snip the code below and play with it. it shows both the given examples and some additional ways to change/display class variables.
good luck, hackerx
import javax.swing.*;
import java.awt.event.*;
public class Foo extends JPanel
     private boolean the_b = true;
     public static void main(String[] args)
          Foo f = new Foo();
          JFrame frame = new JFrame();
          frame.getContentPane().add(f);
          frame.pack();
          frame.show();
     public Foo()
          // get your button
          JButton b = new JButton("Not!");
          b.addActionListener(new ActionListener()
               public void actionPerformed(ActionEvent ae)
                    // *** uncomment these to play around ***
                    // Foo.this.the_b = false; // this will work, but unnecessary
                    // the_b = false; // this works fine too
                    notFoo();
          this.add(b);
          // something to show the value that accesses a class variable
          // using an inner class instead of final nonsense
          DisplayThread t = new DisplayThread();
          t.start();
     private void notFoo()
          the_b = !the_b;
     class DisplayThread extends Thread
          public void run()
               while(true)
                    System.err.println("boolean value: " + the_b);
                    try {
                    sleep(1000);
                    } catch(InterruptedException ie) {}
}

Inner Class extending the outer class

Could anyone explain this code to me? It can compile and run. Could anyone tell me what the class Main.Inner.Inner is? What members does it consists of? How the compiler manage to build such a class?
public class Main {
    public static class Inner extends Main {
    public static void main(String[] args) {
        System.out.println("Hello, world.");
}

By the way, it's not really an inner class, because it's static. It's just a nested class.
You might want to have a nested class extend its enclosing class if, maybe, you wanted to delegate to subclasses and didn't want to create a lot of extra source code files, which might make sense if the nested subclasses were really small.
public abstract class Animal {
public abstract void makeSound();
private Animal() {} // can't be directly instantiated
private static class Dog extends Animal {
    public void makeSound() { System.out.println("woof"); }
private static class Cat extends Animal {
    public void makeSound() { System.out.println("meow"); }
private static class Zebra extends Animal {
    public void makeSound() { System.out.println("i am a zebra"); }
public static Animal get(String desc) {
    if ("fetches sticks".equals(desc)) {
      return new Dog();
    if ("hunts mice".equals(desc)) {
      return new Cat();
    if ("stripey horse".equals(desc)) {
      return new Zebra();
    return null;
public class AnimalTest {
public static void main(String... argv) {
    Animal a = Animal.get("fetches sticks");
    a.makeSound();
}

Invoke a method in one class from a different class

I am working on a much larger project, but to keep this simple, I wrote out a little test that would convey the over all theory of the program.
What I am doing is starting out with a 2 JFrames and a Class. When the program is launched, the first JFrame opens. In this JFrame is a label and a button. When the button is clicked, the second JFrame opens. This JFrame has a textField and a button. The user puts the text in the textField and presses the button. When the button is pushed, I want the text that was just put in the textField, to be displayed in the first JFrame's label. I am trying to invoke a method in the first JFrame from the second, but nothing happens. I have also tried making the Class extend from JFrame1 and invoke it from there, but no luck. So, how do I invoke a method in a class from a different class?
JFrame1 (I omitted the layout part. I made this in Netbeans so its pretty long)
public class NewJFrame1 extends javax.swing.JFrame {
     private NewClass1 nC = new NewClass1();
     /** Creates new form NewJFrame1 */
     public NewJFrame1() {
          initComponents();
          jLabel1.setText("Chuck");
     public void setLabels()
          jLabel1.setText(nC.getName());
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
     NewJFrame2 j2 = new NewJFrame2();
     j2.setVisible(true);The class
public class NewClass1 {
     public static String name;
     public NewClass1()
     public NewClass1(String n)
          name = n;
     public String getName()
          return name;
     public void setName(String n)
          name = n;
}The second jFrame
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
     NewClass1 nC = new NewClass1();
     NewJFrame1 nF = new NewJFrame1();
     nC.setName(jTextField1.getText());
     nF.setLabels();
     System.out.println(nC.getName());At this point I am begging for help. I have been trying for days to figure this out, and I just feel like I am not getting anywhere.
Thanks

So, how do I invoke a method in a class from a different class?Demo:
public class Main {
    public static void main(String [] args) {
     Test1 t1 = new Test1();
     Test2 t2 = new Test2();
     int i = t1.method1();
     String s = t2.method2(i);
     System.out.println(s);
class Test1 {
    public int method1() {
     return 10;
class Test2 {
    public String method2(int i) {
     if (i == 10)
         return "ten";
     else
         return "nothing";
}Output is "ten".
Edited by: newark on May 28, 2008 10:55 AM

"1046: Type was not found" for a custom class calling a custom class

This should be easy... but I've spent two days on nothing but this error.... I am absolutely at my wit's end.
Basically, I've got a "character" container linked to a MovieClip in the library that is supposed to act as a container for various body parts; head, shirt, pants, etc. For simplicity, I've just got Character class and Head class, both in a "char" package, both classes are named the same as their respective files (Character.as and Head.as, both in an actual file called "char"). Character class is supposed to create an instance of Head, but I always get this 1046 error. The problem is that I've got other body parts with nearly identical classes that ARENT throwing a 1046 error and are working just fine. I went and made a new project to see if I was still having the problem with just character calling 1 simple body part. I do.
In the symbol properties, it's Exported for Actionscript & Export in Frame 1... the class is "char.Head" and "char.Character" respectively. I have tried everything I can find or think of, I've done dozens of Google searches and sifted through dozens of forums. I can't find anything and I've been working on this problem for 24 straight working hours now. I'm completely exasperated......
package char {
import flash.display.MovieClip;
import flash.display.Stage;
import flash.display.Sprite;
import flash.events.Event;
import flash.geom.ColorTransform;
import fl.motion.Color;
import char.Head;
public class Character extends MovieClip {
// 1046: Type was not found or was not a compile-time constant: Head
private var _head:Head;
// reference to get the stage later
private var stageRef:Stage;
public function Character(stageRef:Stage=null) {
trace("NEW CHARACTER");
//1180 Call to a possibly undefined method Head;
_head=new Head();
And here's the contents of Head.as
package char {
import flash.display.MovieClip;
import flash.events.Event;
import flash.display.Stage;
import flash.geom.ColorTransform;
public class Head extends MovieClip {
private var skin_type:uint;
public function Head() {
trace ("NEW HEAD");
Now if I declare the head variable and create a new instance of it in my document class, no problem whatsoever. If I do it in my Character class, it just doesn't stop giving me this error!!! Somebody please help me.
1046: Type was not found or was not a compile-time constant: Head
1180 Call to a possibly undefined method Head;

There is a blank movieclip named Character in the library, yup.
Also in my main handler for my document class calls "mainCharacter = new Character(); "
Here's a chunk of the code from the document class. For the record, it calls "head" as just a test and that works fine. Just doesn't work in "Character"
import char.Character;
import char.Head;
public class MainHandler extends MovieClip {
private static var _instance:MainHandler;
public static function get instance():MainHandler { return _instance; }
public var mainCharacter:Character;
public var head_:Head;
public function MainHandler() {
_instance = this;
mainCharacter = new Character();
head_=new Head();

Combining classes into one single class

Hi
I have written a java application that incompasses many classes. When I complie my java code
the complier produced a ClassName.class file for the main class and each and every class.
When I run the application it needs all of the classes not just the main class.
Can someone please show me how to combine all the classes into a single Main class
as when I try and run the program :
i.e java Main.class it needs all the other classes too.
Basically what I am asking is can I compile my program such that all class information
is incorporated in the Main.class?
Thanks

Not really (and it wouldn't be a good idea if you could). You can define one class inside another, but they still produce separate .class files. What you do is to wrap all your class files up in a jar file usint the jar utility. You can add a "manifest" which specifies which is the main class. If you do that you can run the program simply with java -jar xxxx.jar

Instantiation of similar object over a super class deciding the sub class

Hello all
First, sorry if I'm duplicating an already answered question. I didn't searched very deep.
Initial position:
I have 2 Object (A1 and A2) which share the most (about 90%) of their instance variables an the associated methods. The values of the instance variables are retrieved in the real implementation from a stream. Depending of the data of the stream, I have to instantiate either a A1 or A2 object.
A test implementation (using an int in case of the stream):
The super class A:
package aaa;
public class A
protected int version = -1;
protected String name = null;
protected AE ae = null;
protected A()
protected A(int v)
    // Pseudo code
    if (v > 7)
      return;
    if (v % 2 == 1)
      this.version = 1;
    else
      this.version = 2;
public final int getVersion()
    return this.version;
public final String getName()
    return this.name;
public final AE getAE()
    return this.ae;
}The first sub class A1:
package aaa;
public final class A1 extends A
protected A1(int v)
    this.version = v;
    this.name = "A" + v;
    this.ae = new AE(v);
}The second subclass A2:
package aaa;
import java.util.Date;
public final class A2 extends A
private long time = -1;
protected A2(int v)
    this.version = v;
    this.name = "A" + v;
    this.time = new Date().getTime();
    this.ae = new AE(v);
public final long getTime()
    return this.time;
}Another class AE:
package aaa;
public class AE
protected int type = -1;
protected AE(int v)
    // Pseudo code
    if (v % 2 == 1)
      this.type = 0;
    else
      this.type = 3;
public final int getType()
    return this.type;
}To get a specific object, I use this class:
package aaa;
public final class AFactory
public AFactory()
public final Object createA(int p)
    A a = new A(p);
    int v = a.getVersion();
    switch (v)
    case 1:
      return new A1(v);
    case 2:
      return new A2(v);
    default:
      return null;
}And at least, a class using this objects:
import aaa.*;
public final class R
public static void main(String[] args)
    AFactory f = new AFactory();
    Object o = null;
    for (int i = 0; i < 10; i++)
      System.out.println("===== Current Number is " + i + " =====");
      o = f.createA(i);
      if (o instanceof aaa.A)
        A a = (A) o;
        System.out.println("Class   : " + a.getClass().getName());
        System.out.println("Version : " + a.getVersion());
        System.out.println("Name    : " + a.getName());
        System.out.println("AE-Type : " + a.getAE().getType());
      if (o instanceof aaa.A2)
        A2 a = (A2) o;
        System.out.println("Time    : " + a.getTime());
      System.out.println();
Questions:
What would be a better way to encapsulate the logic into their respective objects ? Is there a way to let the super class A itself identify the type of the object and then extend from A to either A1 or A2 ?
Thanks in advance
Andreas

Hello jduprez
First, I would thank you very much for taking the time reviewing my problem.
Just for the record: have you considered regular serialization? If you control the software at both ends of the stream, you could rely on standard serialization mechanism to marshall the objects and unmarshall them automatically.In my case, I can't control the other site of the stream. At the end, the data comes from a FileInputStream and there aren't objects on the other site, only pur binary data.
- It seems you have one such factory class. Then you already have encapsulated the "determine class" logic, you don't need to add such logic in superclass A.I thought from an OO view, that the super class A is responsible of doing that, but that's where the problem starts. So at the end, it's better doing it in the factory class.
- A itself encapsulates the logic to load its own values from the stream.
- A1 and A2 can encapsulate the logic to load their own specific value from a stream (after the superclass' code has loaded the superclass' attributes values).
My advise would be along the lines of:
public class A {
.... // member variables
public void load(InputStream is) {
... // assign values to A's member variables
// from what is read from the stream.
public class A1 extends A {
... // A1-specific member variables
public void load(InputStream is) {
super.load(is);
// now read A1-specific values
public class AFactory {
public A createA(InputStream is) {
A instance;
switch (is.readFirstByte()) {
case A1_ID:
a = new A1();
break;
case A2_ID:
a = new A2();
break;
a.load(is);
}The example above assumes you have control over the layout of the data in the stream (here for a given A instance, the attributes defined in A are read first, then come the subclass-specific attributes.
The outcome is: you don't have to create a new A( ) to later create another instance, of a subclass.I like the idea. In the AFactory, is the "A instance;" read as "A a;" ?
Is there a way to let the super class A itself identify the type of the object and then extend from A to either A1 or A2 ?Note I initially read this question as "can an instance of a class mutate into another class", to which the answer is no (an object has one single, immutable class; it is an instance of this class, and of any superclass and superinterface, but won't change its class at runtime).Yes, I have been thinking about a way for mutating into a subclass to keep the already initialized values from the A class without copying or parsing again. But preventing an instance of an A class will be my way. So, in this aspect, Java didn't changed in the last 10 years... It's a long time ago I've used Java for some real projects.
You can, however, create an instance of another class, that copies the values off a priori A instance. Your example code was one way, another way could be to have a "copy constructor":
public class A {
public A(A model) {
this.att1 = model.att1;
this.att2 = model.att2;
public class A1 {
public A1(A model) {
super(model);
... // do whatever A1-specific business
)Still, I prefer my former solution less disturbing: I find the temporary A instance redundant and awkward.Nice to know. I prefer the first solution too.
Thank you again for the help and advices. My mind is searching sometimes for strange solutions, where the real is so close ;-)
Andreas

Public class or just simply class?

Similar Messages

Maybe you are looking for