Clearing weak references with inner classes

I have a class which contains several inner classes. During it's lifetime, this object creates several instances of it's internal objects and uses them only internally.
I also have a single weak reference that links to my object from anywhere external to the program.
While profiling, I discovered a memory leak. After examining the core dump under jhat, it appears that the only objects linking to this object are that weak reference from the external program and several intantiated inner classes that reference my object via their implicit this$0 field.
Is this possible? Does mixing inner classes and weak references stop the garbage collector from reclaiming classes?

Based on the information you provide, I question your assertion that these inner objects are used only internally. The most obvious explanation is that you're leaking them and something else is holding a hard reference to them.

Similar Messages

Problems with inner classes in JasminXT

I hava problems with inner classes in JasminXT.
I wrote:
;This is outer class
.source Outer.j
.class Outer
.super SomeSuperClass
.method public createrInnerClass()V
     .limit stack 10
     .limit locals 10
     ;create a Inner object
     new Outer$Inner
     dup
     invokenonvirtual Outer$Inner/<init>(LOuter;)V
     ;test function must print a Outer class name
     invokevirtual Outer$Inner/testFunction ()V
.end method
;This is inner class
.source Outer$Inner.j
.class Outer$Inner
.super java/lang/Object
.field final this$0 LOuter;
;contructor
.method pubilc <init>(LOuter;)V
     .limit stack 10
     .limit locals 10
     aload_0
     invokenonvirtual Object/<init>()V
     aload_0
     aload_1
     putfield Inner$Outer/this$0 LOuter;
     return
.end method
;test
.method public testFunction ()V
     .limit stack 10
     .limit locals 10
     ;get out object
     getstatic java/io/PrintStream/out java/io/PrintStream;
     aload_0
     invokevirtual java/lang/Object/getClass()java/lang/Class;
     ;now in stack Outer$Inner class
     invokevirtual java/Class/getDeclaringClass()java/lang/Class;
     ;but now in stack null
     invokevirtual java/io/PrintStream/print (Ljava/lang/Object;)V
.end methodI used dejasmin. Code was equal.
What I have to do? Why getDeclatingClass () returns null, but in dejasmin code
it returns Outer class?

Outer$Inner naming convention is not used by JVM to get declaring class.
You need to have proper InnerClasses attribute (refer to http://java.sun.com/docs/books/vmspec/2nd-edition/html/ClassFile.doc.html#79996)
in the generated classes. Did you check using jclasslib or another class file viewer and verified that your .class files have proper InnerClasses attribute?

Issue with JSPs with inner classes (bug)

FYI:
Turning on Versioning in the registry (Disable=0) JSPs with inner classes causes the following IllegalAccessException...
This has been confirmed with SP3 and SP4 with our testing...
14/Jan/2002 13:26:24:4] error: Exception: SERVLET-run_failed: Failed in running template: /NASApp/fortune/foo.jsp, java
lang.IllegalAccessError: try to access class jsp.APPS.fortune.foo$foobar from class jsp.APPS.fortune.foo
xception Stack Trace:
ava.lang.IllegalAccessError: try to access class jsp.APPS.fortune.foo$foobar from class jsp.APPS.fortune.foo
at jsp.APPS.fortune.foo._jspService(foo.java:78)
at org.apache.jasper.runtime.HttpJspBase.service(Unknown Source)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:865)
at com.netscape.server.servlet.servletrunner.ServletInfo.service(Unknown Source)
at com.netscape.server.servlet.servletrunner.ServletRunner.callJSP(Unknown Source)
at com.netscape.server.servlet.platformhttp.PlatformHttpServletResponse.callJspCompiler(Unknown Source)
at com.netscape.server.servlet.platformhttp.PlatformHttpServletResponse.callUri(Unknown Source)
at com.netscape.server.servlet.platformhttp.PlatformHttpServletResponse.callUriRestrictOutput(Unknown Source)
at com.netscape.server.servlet.platformhttp.PlatformRequestDispatcher.forward(Unknown Source)
at com.netscape.server.servlet.jsp.JSPRunner.service(Unknown Source)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:865)
at com.netscape.server.servlet.servletrunner.ServletInfo.service(Unknown Source)
at com.netscape.server.servlet.servletrunner.ServletRunner.execute(Unknown Source)
at com.kivasoft.applogic.AppLogic.execute(Unknown Source)
at com.kivasoft.applogic.AppLogic.execute(Unknown Source)
at com.kivasoft.thread.ThreadBasic.run(Native Method)
at java.lang.Thread.run(Thread.java:479)
Looking for work around....
Cheers,
Martin Gee

I do not see why you would use two sorts.
And what is the issue exactly by the way? Errors?
So, the records before the Merge Join need to come sorted, to achieve this simply tick:
Arthur My Blog

How to reference an inner class with @link?

Hi,
Let's assume we have a class Test with an inner class namned InnerTest. If I want to put a @link to a method in InnerTest in another java-file, what do I write?
To reference a method in Test, I write:
{@link com.company.Test#method}
My first thought when referencing the inner class' method was to just write:
{@link com.company.Test.InnerTest#method}
but this doesn't seem to be the correct way.
Any help is greatly appreciated! Thank you in advance.

You're calling the method in the inner class the right way.
You're probably experiencing bugs with links.
I don't know what version you're using, but 1.4.0 and
1.4.1 have some severe bugs. Please see another
thread in this forum entitled:
"Some {@link} tags do not seem to generate hyperlinks"
-Doug Kramer
Javadoc team

Problems importing a class with inner class

Why can't I import a class so that I can use an (inner) static member class without naming the enclosing class. Put simply, I have:
file C:\MyJava\Test\A:
public class A {
public static class B { }
}file C:\MyJava\Test\C
import A.*;
public class C { }When I try to compile C (javac -classpath C:\MyJava\Test;. C.java) it fails with C.java:1: package A does not exist

Class A must be in a package if you wish to import it. If you want to use the inner class, just import somepackage.A. You could then refer to A.B...
HTH :o)

Strange behaviour of JBuilder Plug-In with Inner class

Hi, I'm using the Kodo 2.5.2 Plug-In with JBuilder 8. I have an inner
persistent class. It seems that it is necessary to have a zero length file
named EnclosingClass$InnerClass.java for the build process to work, since
if I delete this file and run the application it throws an exception
saying that the Inner class has not an specified field which it really
has. I don't know if this is a bug of the Kodo implementation or of the
JBuilder Plug-In.
Thanks for any help.
Jaime.

This is one of the limitations of the JBuilder plugin. Hopefully it
will be resolved in the next iteration of our plugins for 3.x.
Jaime De La Jara F. wrote:
Hi, I'm using the Kodo 2.5.2 Plug-In with JBuilder 8. I have an inner
persistent class. It seems that it is necessary to have a zero length file
named EnclosingClass$InnerClass.java for the build process to work, since
if I delete this file and run the application it throws an exception
saying that the Inner class has not an specified field which it really
has. I don't know if this is a bug of the Kodo implementation or of the
JBuilder Plug-In.
Thanks for any help.
Jaime.
Steve Kim
[email protected]
SolarMetric Inc.
http://www.solarmetric.com

Error with inner Classes

I've a Swing app in wich I've the following code :
final ComboBoxEditor editor = comboBox.getEditor();
editor.getEditorComponent().addKeyListener(new java.awt.event.KeyAdapter() {
public void keyReleased(KeyEvent e) {
combo_keyReleased(e,editor);
Runned in a normal way it works, runned via Webstart 1.4.2 it gives me :
java.lang.ClassFormatError: it/axioma/basic/application/templates/ClWidgetCombo$2 (Illegal Variable name " val$editor")
     at java.lang.ClassLoader.defineClass0(Native Method)
     at java.lang.ClassLoader.defineClass(Unknown Source)
     at java.security.SecureClassLoader.defineClass(Unknown Source)
     at com.sun.jnlp.JNLPClassLoader.defineClass(Unknown Source)
     at com.sun.jnlp.JNLPClassLoader.access$100(Unknown Source)
     at com.sun.jnlp.JNLPClassLoader$1.run(Unknown Source)
etc...
Could someone explain me why ?
Is there any workaround ?
TIA
Tullio

There seems to be a problem using final variables with anonymous inner classes under a different classloader, see http://forum.java.sun.com/thread.jsp?forum=38&thread=372291

Null pointer exception with inner class

Hi everyone,
I've written an applet that is an animation of a wheel turning. The animation is drawn on a customised JPanel which is an inner class called animateArea. The main class is called Rotary. It runs fine when I run it from JBuilder in the Applet Viewer. However when I try to open the html in internet explorer it gives me null pointer exceptions like the following:
java.lang.NullPointerException
at sun.java2d.SunGraphics2D.drawImage(SunGraphics2D.java:2761)
at sun.java2d.SunGraphics2D.drawImage(SunGraphics2D.java:2722)
at Rotary$animateArea.paintComponent(Rotary.java:251)
at javax.swing.JComponent.paint(JComponent.java:808)
at javax.swing.JComponent.paintWithOffscreenBuffer(JComponent.java:4771)
at javax.swing.JComponent.paintDoubleBuffered(JComponent.java:4724)
at javax.swing.JComponent._paintImmediately(JComponent.java:4668)
at javax.swing.JComponent.paintImmediately(JComponent.java:4477)
at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:410)
at javax.swing.SystemEventQueueUtilities$ComponentWorkRequest.run(SystemEventQueueUtilities.java:117)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:178)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:448)
at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:197)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:144)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:136)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:99)
Do inner classes have to be compiled seperately or anything?
Thanks a million for you time,
CurtinR

I think that I am using the Java plugin ( Its a computer in college so I'm not certain but I just tried running an applet from the Swing tutorial and it worked)
Its an image of a rotating wheel and in each sector of the wheel is the name of a person - when you click on the sector it goes red and the email window should come up (that doesn't work yet though). The stop and play buttons stop or start the animation. It is started by default.
This is the code for the applet:
import java.applet.*;
import javax.swing.JApplet;
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import java.awt.geom.*;
import javax.swing.*;
import java.awt.image.*;
import java.util.StringTokenizer;
import java.net.*;
public class Rotary extends JApplet implements ActionListener, MouseListener
public boolean rotating;
private Timer timer;
private int delay = 1000;
private AffineTransform transform;
private JTextArea txtTest; //temp
private Container c;
private animateArea wheelPanel;
private JButton btPlay, btStop;
private BoxLayout layout;
private JPanel btPanel;
public Image wheel;
public int currentSector;
public String members[];
public int [][]coordsX, coordsY; //stores sector no. and x or y coordinates for that point
final int TOTAL_SECTORS= 48;
//creates polygon array - each polygon represents a sector on wheel
public Polygon polySector1,polySector2,polySector3, polySector4, polySector5,polySector6,polySector7,polySector8,polySector9,polySector10,
polySector11,polySector12,polySector13,polySector14,polySector15,polySector16,polySector17,polySector18,polySector19,polySector20,
polySector21,polySector22,polySector23,polySector24,polySector25,polySector26,polySector27,polySector28,polySector29,polySector30,
polySector31,polySector32,polySector33,polySector34,polySector35,polySector36,polySector37,polySector38,polySector39,polySector40,
polySector41,polySector42,polySector43,polySector44,polySector45,polySector46,polySector47,polySector48;
public Polygon polySectors[]={polySector1,polySector2,polySector3, polySector4, polySector5,polySector6,polySector7,polySector8,polySector9,polySector10,
                  polySector11,polySector12,polySector13,polySector14,polySector15,polySector16,polySector17,polySector18,polySector19,polySector20,
                  polySector21,polySector22,polySector23,polySector24,polySector25,polySector26,polySector27,polySector28,polySector29,polySector30,
                  polySector31,polySector32,polySector33,polySector34,polySector35,polySector36,polySector37,polySector38,polySector39,polySector40,
                  polySector41,polySector42,polySector43,polySector44,polySector45,polySector46,polySector47,polySector48};
public void init()
members = new String[TOTAL_SECTORS];
coordsX= new int[TOTAL_SECTORS][4];
coordsY= new int[TOTAL_SECTORS][4];
currentSector = -1;
rotating = true;
transform = new AffineTransform();
//***********************************Create GUI**************************
wheelPanel = new animateArea(); //create a canvas where the animation will be displayed
wheelPanel.setSize(600,580);
wheelPanel.setBackground(Color.yellow);
btPanel = new JPanel(); //create a panel for the buttons
btPanel.setLayout(new BoxLayout(btPanel,BoxLayout.Y_AXIS));
btPanel.setBackground(Color.blue);
btPanel.setMaximumSize(new Dimension(30,580));
btPanel.setMinimumSize(new Dimension(30,580));
btPlay = new JButton("Play");
btStop = new JButton("Stop");
//txtTest = new JTextArea(5,5); //temp
btPanel.add(btPlay);
btPanel.add(btStop);
// btPanel.add(txtTest); //temp
c = getContentPane();
layout = new BoxLayout(c,layout.X_AXIS);
c.setLayout(layout);
c.add(wheelPanel); //add panel and animate canvas to the applet
c.add(btPanel);
wheel = getImage(getDocumentBase(),"rotary2.gif");
getParameters();
for(int k = 0; k <TOTAL_SECTORS; k++)
polySectors[k] = new Polygon();
for(int n= 0; n<4; n++)
polySectors[k].addPoint(coordsX[k][n],coordsY[k][n]);
btPlay.addActionListener(this);
btStop.addActionListener(this);
wheelPanel.addMouseListener(this);
startAnimation();
public void mouseClicked(MouseEvent e)
if (rotating == false) //user can only hightlight a sector when wheel is not rotating
for(int h= 0; h<TOTAL_SECTORS; h++)
if(polySectors[h].contains(e.getX(),e.getY()))
currentSector = h;
wheelPanel.repaint();
email();
public void mouseExited(MouseEvent e){}
public void mouseEntered(MouseEvent e){}
public void mouseReleased(MouseEvent e){}
public void mousePressed(MouseEvent e){}
public void email()
try
URL rotaryMail = new URL("mailto:[email protected]");
getAppletContext().showDocument(rotaryMail);
catch(MalformedURLException mue)
System.out.println("bad url!");
public void getParameters()
StringTokenizer stSector;
String parCoords;
for(int i = 0; i <TOTAL_SECTORS; i++)
{               //put member names in applet parameter list into an array
members[i] = getParameter("member"+i);
//separate coordinate string and store coordinates in 2 arrays
parCoords=getParameter("sector"+i);
stSector = new StringTokenizer(parCoords, ",");
for(int j = 0; j<4; j++)
coordsX[i][j] = Integer.parseInt(stSector.nextToken());
coordsY[i][j] = Integer.parseInt(stSector.nextToken());
public void actionPerformed(ActionEvent e)
wheelPanel.repaint(); //repaint when timer event occurs
if (e.getActionCommand()=="Stop")
stopAnimation();
else if(e.getActionCommand()=="Play")
startAnimation();
public void startAnimation()
if(timer == null)
timer = new Timer(delay,this);
timer.start();
else if(!timer.isRunning())
timer.restart();
Thanks so much for your help!

Problems with inner classes

I ran into the following problems when I tried to read into an inner class:
This is my .jdo file
<?xml version="1.0"?>
<jdo>
<package name="com.globalrefund.jdo.mna">
<class name="Parameter$Syspar" objectid-class="SysparId">
<extension vendor-name="kodo" key="table" value="syspar"/>
<extension vendor-name="kodo" key="lock-column" value="none"/>
<extension vendor-name="kodo" key="class-column" value="none"/>
<field name="landescode" primary-key="true">
<extension vendor-name="kodo" key="data-column"
value="landescode"/>
</field>
<field name="waehrungscode">
<extension vendor-name="kodo" key="data-column"
value="waehrungscode"/>
</field>
</class>
</package>
</jdo>
1.) appidtool does not work for this inner class, I get this stack trace
C:\users\Bernhard\jbProject\refundManual>appidtool
src\com\globalrefund\jdo\mna\Parameter$Syspar.jdo
Generating an application id for type "class
com.globalrefund.jdo.mna.Parameter$Syspar"...
Exception in thread "main" java.lang.NullPointerException
at com.solarmetric.kodo.enhance.ApplicationIdTool.getFile(Unknown
Source)
at
com.solarmetric.kodo.enhance.ApplicationIdTool.writeApplicationId(Unknown
Source)
at
com.solarmetric.kodo.enhance.ApplicationIdTool.writeApplicationId(Unknown
Source)
at com.solarmetric.kodo.enhance.ApplicationIdTool.main(Unknown
Source)
2.) I tried to use a hand coded inner class as ID class, but id did not work
(is this not possible ?)
Exception in thread "main" java.lang.NoSuchMethodError:
com.globalrefund.jdo.mna.Parameter$SysparId: method <init>()V not found
at
com.globalrefund.jdo.mna.Parameter$Syspar.jdoNewObjectIdInstance(Parameter.j
ava)
at
javax.jdo.spi.JDOImplHelper.newObjectIdInstance(JDOImplHelper.java:166)
at com.solarmetric.kodo.util.ObjectIds.fromPKValues(Unknown Source)
at
com.solarmetric.kodo.impl.jdbc.runtime.JDBCStoreManager.createFromResultSet(
Unknown Source)
at
com.solarmetric.kodo.impl.jdbc.runtime.JDBCStoreManager$2.getResultObject(Un
known Source)
at
com.solarmetric.kodo.impl.jdbc.runtime.LazyResultList.instantiateRow(Unknown
Source)
at com.solarmetric.kodo.impl.jdbc.runtime.LazyResultList.get(Unknown
Source)
at java.util.AbstractList$Itr.next(AbstractList.java:416)
at com.solarmetric.kodo.runtime.ResultListIterator.next(Unknown
Source)
at
com.solarmetric.kodo.impl.jdbc.runtime.ResultListFactory.createResultList(Un
known Source)
at
com.solarmetric.kodo.impl.jdbc.runtime.JDBCStoreManager.executeQuery(Unknown
Source)
at
com.solarmetric.kodo.impl.jdbc.runtime.JDBCQuery.executeQuery(Unknown
Source)
at com.solarmetric.kodo.query.QueryImpl.executeWithMap(Unknown
Source)
at com.solarmetric.kodo.query.QueryImpl.execute(Unknown Source)
at
com.solarmetric.kodo.query.QueryImpl$SynchronizedQuery.execute(Unknown
Source)
at com.globalrefund.jdo.mna.Parameter.<init>(Parameter.java:71)
3.) It worked after I moved the ID class into a separate class
Regards,
Bernhard

1.) appidtool does not work for this inner class, I get this stack traceThis is a bug. It will be corrected in the final release of 2.3, due out
Real Soon Now. Thanks for catching this!
2.) I tried to use a hand coded inner class as ID class, but id did not work
(is this not possible ?)
Exception in thread "main" java.lang.NoSuchMethodError:
com.globalrefund.jdo.mna.Parameter$SysparId: method <init>()V not foundThis exception is saying that your application ID class does not have a
no-args constructor. Make sure the id class is a static inner class;
otherwise Java transparently adds a parent object parameter to each
constructor, and so the application id class will violoate the JDO constraint
of having a no-args constructor.

Please need help with Inner Classes

Hi! I have the following inner class, but it is not an "explicit" inner class:
import java.util.*;
public class EXTERIOR_NOEXPLICITA {
     private Vector i;
     public void llena_Vector(int a){
          i = new Vector();
          for(int z=0;z<=a;z++)
               i.addElement(""+z);
     public Enumeration test() {
          return new Enumeration(){
               int item = i.size()-1;
               public boolean hasMoreElements(){
                    return(item >= 0);
               public Object nextElement(){
                    if(!hasMoreElements())
                         throw new NoSuchElementException();
                    else
                         return i.elementAt(item--);
My question is, how can I put it in an explicyt inner class?
Plese help me! =)
Raul

I am not entirely sure what you mean by explicit inner class. If you mean converting your anonymous class into a nested class, then it is quite easy:
import java.util.*;
public class EXTERIOR_NOEXPLICITA {
private Vector i;
public void llena_Vector(int a) {
    i = new Vector();
    for (int z = 0; z <= a; z++)
      i.addElement("" + z);
private final class MyEnumeration implements Enumeration {
    int item = i.size() - 1;
    public boolean hasMoreElements() {
      return (item >= 0);
    public Object nextElement() {
      if (!hasMoreElements())
        throw new NoSuchElementException();
      else
        return i.elementAt(item--);
public Enumeration test() {
    return new MyEnumeration();

Trouble with inner class

jDeveloper 10.1.3.0.4
i want to see the var Variable into a inner class
public class myClass extends JFrame{
int Variable;
myClass(){
fuction1();
private fuction1(){
jlogonOptionPane.addPropertyChangeListener(new PropertyChangeListener() {
public void propertyChange(PropertyChangeEvent e) {
// here, i wan to use Variable
}// fuction1
}// myclass
why i cant see varible into propertyChange ?

Hi,
your code isn't complete and misses the jlogonOptionPane definition. If you use
package adf.sample.view;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
public class MyClass extends JFrame{
private int mvariable = 2;
MyClass(){
function1();
private void function1(){
JOptionPane jlogonOptionPane = new JOptionPane();
jlogonOptionPane.addPropertyChangeListener(new PropertyChangeListener() {
public void propertyChange(PropertyChangeEvent e) {
// here, i wan to use Variable
}// fuction1
}// myclass
set the curser after
// here, i wan to use Variable
- hold the ctrl key and press the blank key
- type mv and you will se mvariable
Frank

Troubles with inner classes in swing-panel

hi,
I'm having troubles using innner classes as ActionListeners in my swing-panel. I keep getting compile-time errors:
C:\Java programmer\DocGenerator\ListPanel.java:53: cannot resolve symbol
symbol : class Actionlistener
location: class ListPanel.RemoveListener
     class RemoveListener implements Actionlistener {
^
C:\Java programmer\DocGenerator\ListPanel.java:33: addActionListener(java.awt.event.ActionListener) in javax.swing.AbstractButton cannot be applied to (ListPanel.RemoveListener)
          removeButton.addActionListener(new RemoveListener());
^
2 errors
Here is the source code:
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
class ListPanel extends JPanel implements ListSelectionListener{
     private JButton addButton = new JButton("add");
     private JButton removeButton = new JButton("remove");
     private JButton resetButton = new JButton("reset");
     private JList list;
     private DefaultListModel listModel;
     public ListPanel(){
          listModel = new DefaultListModel();
          listModel.addElement("nummer1");
          listModel.addElement("nummer2");
          list = new JList(listModel);
          list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
          list.setSelectedIndex(0);
          list.addListSelectionListener(this);
          JScrollPane listScrollPane = new JScrollPane(list);
          setLayout(new GridLayout(1,2));
          JPanel buttons = new JPanel();
          buttons.setLayout(new GridLayout(3,1));
//          addButton.addActionListener(this);
          removeButton.addActionListener(new RemoveListener());
//          resetButton.addActionListener(this);
          buttons.add(addButton);
          buttons.add(removeButton);
          buttons.add(resetButton);
          list.setBorder(BorderFactory.createLineBorder(Color.black,3));
          add(buttons);
          add(list);
     public void actionPerformed(ActionEvent e){
          System.out.println(e);
     public void valueChanged(ListSelectionEvent e){
     class RemoveListener implements Actionlistener {
          public void actionPerformed(ActionEvent e){
               int index = list.getSelectedIndex();
               listModel.remove(index);
               int size = listModel.getSize();
               if(size==0){
                    addButton.setEnabled(false);
               } else {
                    if (index==listModel.getSize())
                         index--;
                    list.setSelectedIndex(index);

Both of the errors is because Actionlistener is not the same as ActionListener. Note the capital 'L' there!

General class and setting properties vs specific inner class

This is a general question for discussion. I am curious to know how people differentiate between instantiating a standard class and making property adjustments within a method versus defining a new inner class with the property adjustments defined within.
For example, when laying out a screen do you:
- instantiate all the objects, set properties, and define the layout all within a method
- create an inner class that defines the details of the layout (may reference other inner classes if complex) that is then just instantiated within a method
- use some combination of the two depending on size and complexity.
- use some other strategy
Obviously, by breaking the work up into smaller classes you are simplifying the structure since each class is taking on less responsibility, as well as hiding the details of the implementaion from higher level classes. On the other hand, if you are just instantiating an object and making some SET calls is creating an inner class overkill.
Is there a general consensus for an approach? I am curious to hear the approach of others.

it's depends on your design..
usually, if the application is simple and is not expected to be maintain (update..etc..) than I just have all the building of the gui within the same class (usually..the main class that extends JFrame).
if the application follows the MVC pattern, than I would have a seperate class that build the GUI for a particular View. I would create another class to handle the ActionEvent, and other event (Controller)
I rarely use inner class...and only use them to implements the Listerner interface (but only for simple application)..

Servicegen and inner classes

I have a class that contains a public non-static inner class. Even though the inner class has a public default contructor, servicegen claims it can't find the constructor.
Is this a servicegen bug or limitation with inner classes?

Hi Ron,
Sounds like a bug. Could you supply a short example?
Thanks,
Bruce
Ron Mak wrote:
I have a class that contains a public non-static inner class. Even though the inner class has a public default contructor, servicegen claims it can't find the constructor.
Is this a servicegen bug or limitation with inner classes?

Javadoc, generics and inner classes

I have implemented a generic class DiGraph with inner classes Vertex and Edge:
public class DiGraph<V,E> implements Iterable<DiGraph<V,E>.Vertex> {
   public Vertex addVertex(V value) {...}
   public Iterator<DiGraph<V,E>.Vertex> iterator() {... }
   public class Vertex implements Iterable<Edge> {
      V value;
   public class Edge {
      E value;
}When i run Javadoc it yields the following documentation of the class DiGraph :
public class DiGraph extends Object implements Iterable<DiGraph.Vertex>What I expected was
public class DiGraph extends Object implements Iterable<DiGraph<V,E>.Vertex>In a similar way the method addVertex appears as:
public DiGraph.Vertex addVertex(V value)instead of
public DiGraph<V,E>.Vertex addVertex(V value)This is very confusing, because if I create a graph
DiGraph<String,Integer> myGraph and the use e.g., the method addVertex I must write:
DiGraph<String,Integer>.Vertex v = myGraph.addVertex("a");Can anyone explain why the documentation lacks <V,E> ?

One more dumbshit question...
Is there a way to do this without the warnings OR the @SuppressWarnings({"unchecked"})
   * Returns the index of the last occurrence of the specified element in this
   * list, or -1 if this list does not contain the element.
//@SuppressWarnings({"unchecked"})
public int lastIndexOf(Object object) {
    int i = 0;
    int last = -1;
    for(Node<E> node=this.head.next; node!=null; node=node.next) {
      if (node.item.equals((E) object)) {
        last = i;
      i++;
    return(last);
produces the warning
C:\Java\home\src\linkedlist\LinkedList.java:313: warning: [unchecked] unchecked cast
found   : java.lang.Object
required: E
      if (node.item.equals((E) object)) {
                               ^... remembering that List specifies +public int lastIndexOf(Object object);+ as taking a raw Object, not E element, as I would have expected.
Thanx all. Keith.

Clearing weak references with inner classes

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