Event handling and inner classes

Hi everyone,
When assigning an actionlistener object to a swing component, is making the encapsulating component implement actionlistener better performance-wise than using inner classes? I ask this because my application is pretty slow to start-up, and I'm using lots of inner classes.
I don't want to go ahead and change the event-handling unless I'm sure it will do any good, because the time restriction is too tight for wasting. Does using addActionListener(this) just pass a reference to itself or is an object generated for each call?
Thanks in advance,
Richard

Passing this only passes a reference. But you won't get a big improvement over inner classes. (If you use one listener object instance and pass that instance to the event sources. Do you?)
Kurta

Similar Messages

Annonymous and inner classes

Hello,
Can anyone tell me what the benefits of anonymous and inner classes are? inner classes are seem pretty complicated without any obvious benefit.
I have read about these in books and have some understanding of them but these don't appear to have any benefits.
Any info on either would be really cool.
regards

There are many places where inner classes can be useful. One place where anonymous inner classes are particularly neat is for ActionListeners. For example, compare the "normal" way of doing it:
     for(int i = 0; i < 2; i++)
          JButton button = new JButton("Button " + i);
          button.setActionCommand("ACTION" + i);
          button.addActionListener(this);
     public void actionPerformed(ActionEvent e)
          if("ACTION0".equals(e.getActionCommand()))
               doSomething(0);
          else if("ACTION1".equals(e.getActionCommand()))
               doSomething(1);
     }with the way using anonymous inner classes:
     for(int i = 0; i < 2; i++)
          final int index = i;
          JButton button = new JButton("Button " + index);
          button.addActionListener(new ActionListener()
                    public void actionPerformed(ActionEvent e)
                         doSomething(index);
     .In the first case you need a global actionPerformed method with some if statements inside. If there are many types of action then this can quickly become very large and error-prone. In the second case, each action is handled in its own class, right with the button that it's associated with. This is easier to maintain. Note that local variables must be declared final to be accessible from the inner class.

RMI, event handling, and Winow.dispose()

Hi all,
If you combine RMI with an event handler and java.awt.Window.dispose(), the JVM hangs. The only way to solve this problem is by disposing of the frame from within SwingUtilities.invokeLater.
Please check the following code:
ServerInterface.java:_
import java.rmi.Remote;
import java.rmi.RemoteException;
public interface ServerInterface extends Remote {
    void Send(ClientInterface CI) throws RemoteException;
ClientInterface.java:_
import java.rmi.Remote;
import java.rmi.RemoteException;
public interface ClientInterface extends Remote {
    void Send() throws RemoteException;
Server.java:_
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
import java.rmi.Naming;
public class Server extends UnicastRemoteObject implements ServerInterface {
public Server() throws RemoteException {}
public void Send (ClientInterface CI)
try { CI.Send(); } catch (Throwable t){System.out.println(t);}
public static void main(String args[])
try {
      Naming.rebind      ( "rmi://localhost:1099/Testing",new Server() );
      System.err.println ("Server ready");
catch ( Throwable t )
        System.out.println ( t );
Client.java:_
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
import java.rmi.Naming;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.SwingUtilities;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JButton;
public class Client extends UnicastRemoteObject implements ClientInterface,ActionListener {
static JFrame A=null;
static ServerInterface ServerSide;
private Client() throws RemoteException {}
public void Send()
if ( A == null )
     A = Display("Remove");                   // display frame
else                                // remove frame
     SwingUtilities.invokeLater ( new Runnable(){public void run(){A.dispose();A=null;}} );
public static void main(String[] args)
try {
      ServerSide = (ServerInterface) Naming.lookup ( "rmi://localhost:1099/Testing" );
      ServerSide.Send(new Client());
catch ( Throwable t )
        System.out.println ( t );
public void actionPerformed(ActionEvent e)
try { ServerSide.Send(new Client()); } catch (Throwable t){System.out.println(t);}
private JFrame Display (String label)
JButton b = new JButton (label);
b.addActionListener(this);
JPanel p = new JPanel ();
p.add (b);
JFrame frame = new JFrame ();
frame.getContentPane().add(p);
frame.pack();
frame.setVisible(true);
return frame;
}You can do any GUI work from within an event handler, only when you try to dispose of a frame, the system hangs !!!

Thank you for responding to my problem.
unless their documentation says otherwise (eg: repaint). I checked the API for "repaint()", but it didn't mention anything about the EDT. What documentation you are referring to ?
What I don't understand is that why "dispose()" works well on non-RMI systems and hangs the machine on RMI systems ? It even works fine on RMI system providing that you are not disposing of the frame from within an event handler. So the problem occurs only if you are combining the three elements: RMI, event handler, and dispose().
Conversely, you should avoid doing anything that may take a long time on the EDT. Perhaps remote methods fall into that category.It is true that we should avoid doing anything that may take a long time on the EDT; however, in this particular example, dispose() is not done through a remote call, it is done on the client where the frame should be removed.
I also tried disposing of the frame from within a normal Thread (instead of the EDT), and it worked just fine.

Are enums and inner classes allowed in taglib function signatures??

Hi,
I have a taglib with the following function definition:
<function>
        <description>Determine if viewing a patient attribute is allowed</description>
        <name>isViewingPatientAttributeAllowed</name>
        <function-class>com.example.admin.authorization.UserAuthorizer</function-class>
        <function-signature>boolean isViewingPatientAttributeAllowed(com.example.bean.User, com.example.bean.Patient.PatientAttribute, com.example.bean.Patient)</function-signature>
        <example>
            ${ncvi:isViewingPatientAttributeAllowed(user, patientAttribute, patient)}
        </example>
</function>Where com.example.bean.Patient.PatientAttribute is an enum (note package names have been changed to protect the innocent;-). When I try to compile my web app I get the following error:
org.apache.jasper.JasperException: The class com.example.bean.Patient.PatientAttribute specified in the method signature in TLD for the function ncvi:isViewingPatientAttributeAllowed cannot be found. com.example.bean.Patient.PatientAttributeIf I change PatientAttribute to a static inner class of Patient, I still get the error. Are enums and inner classes allowed in function signatures?
Thx.

I think that you'll find it easier to define a non-inner abstract class RefBase, that exposes a removeFromQueue() method, then extend that for your Ref class. That way, the queue just deals with RefBase instances (or ? extends RefBase).
I think that any other approach is going to get the compiler confused, because the compile-time Ref depends on the parameterization of its defining class.

What is the relation between main class and inner classes

hi
i want to make a UML design and o want to know how to draw the relation betwwen the main public class and inner classes?
and what is the relation?

BaffyOfDaffyA wrote:
Please keep in mind that if you spell better you will get better answers and if you add duke stars you will get better answers and if you mark the thread as a question you will get better answers. That will make it look like you are paying attention and that you really want an answer.
My best answer based on your rather vague question:
A minimal public class in a file named "Minimal.java" in the directory named "minimal":
package minimal;
public class Minimal {
private int variable;
public Minimal(int var) {
variable = var;
public int getVariable() {
return variable;
}This would be an example of adding an inner class:
package minimal;
public class Minimal {
private int variable;
public Minimal(int var) {
variable = var;
public int getVariable() {
return variable;
public class Inner {
private int innerVariable;
public Inner(int var) {
innerVariable = var;
public int getInnerVariable() {
return innerVariable;
}The inner class is exactly like any other inner class except if you are accessing it from anything else other than Minimal then you would have to add Minimal. right before Inner for example, where the Minimal class could use
Inner inner = new Inner(5);other classes would have to use
Minimal.Inner inner = new Minimal.Inner(5);
See [Inner Class Example|http://java.sun.com/docs/books/tutorial/java/javaOO/innerclasses.html] or [Nested Classes|http://java.sun.com/docs/books/tutorial/java/javaOO/nested.html] for more information.
He is probably not asking what an inner class is or how to declare one in raw source code. To me he is asking how do I
explain this relationship in a UML diagram and as UML is not and exact science and expression can vary a lot
between UML design applications I didn't want to stab in the dark.
@OP I would say whatever seems most logical to you and your team, write something that reads.

Main method not found and how to implement events in an inner class

How would I put all the event handling methods in an inner class and I have another class that just that is just a main function, but when i try to run the project, it says main is not found. Here are the two classes, first one sets up everything and the second one is just main.
mport java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
public class JournalFrame extends JFrame {
private JLabel dateLabel = new JLabel("Date: ");
private JTextField dateField = new JTextField(20);
private JPanel datePanel = new JPanel(new FlowLayout());
BorderLayout borderLayout1 = new BorderLayout();
JPanel radioPanel = new JPanel();
JPanel statusPanel = new JPanel();
JPanel textAreaPanel = new JPanel();
JPanel buttonPanel = new JPanel();
GridLayout gridLayout1 = new GridLayout();
FlowLayout flowLayout1 = new FlowLayout();
GridLayout gridLayout2 = new GridLayout();
GridLayout gridLayout3 = new GridLayout();
JRadioButton personalButton = new JRadioButton();
JRadioButton businessButton = new JRadioButton();
JLabel status = new JLabel();
JTextArea entryArea = new JTextArea();
JButton clearButton = new JButton();
JButton saveButton = new JButton();
ButtonGroup entryType = new ButtonGroup();
public JournalFrame(){
try {
jbInit();
catch(Exception e) {
e.printStackTrace();
private void initWidgets(){
private void jbInit() throws Exception {
this.getContentPane().setLayout(borderLayout1);
radioPanel.setLayout(gridLayout1);
statusPanel.setLayout(flowLayout1);
textAreaPanel.setLayout(gridLayout2);
buttonPanel.setLayout(gridLayout3);
personalButton.setSelected(true);
personalButton.setText("Personal");
personalButton.addActionListener(new JournalFrame_personalButton_actionAdapter(this));
businessButton.setText("Business");
status.setText("");
entryArea.setText("");
entryArea.setColumns(10);
entryArea.setLineWrap(true);
entryArea.setRows(30);
entryArea.setWrapStyleWord(true);
clearButton.setPreferredSize(new Dimension(125, 25));
clearButton.setText("Clear Journal Entry");
clearButton.addActionListener(new JournalFrame_clearButton_actionAdapter(this));
saveButton.setText("Save Journal Entry");
saveButton.addActionListener(new JournalFrame_saveButton_actionAdapter(this));
this.setTitle("Journal");
gridLayout3.setColumns(1);
gridLayout3.setRows(0);
this.getContentPane().add(datePanel, BorderLayout.NORTH);
this.getContentPane().add(radioPanel, BorderLayout.WEST);
this.getContentPane().add(textAreaPanel, BorderLayout.CENTER);
this.getContentPane().add(buttonPanel, BorderLayout.EAST);
entryType.add(personalButton);
entryType.add(businessButton);
datePanel.add(dateLabel);
datePanel.add(dateField);
radioPanel.add(personalButton, null);
radioPanel.add(businessButton, null);
textAreaPanel.add(entryArea, null);
buttonPanel.add(clearButton, null);
buttonPanel.add(saveButton, null);
this.getContentPane().add(statusPanel, BorderLayout.SOUTH);
statusPanel.add(status, null);
this.pack();
setDefaultCloseOperation(EXIT_ON_CLOSE);
private void saveEntry() throws IOException{
if( personalButton.isSelected())
String file = "Personal.txt";
BufferedWriter bw = new BufferedWriter(new FileWriter(file,true));
entryArea.getText();
bw.write("Date: " + dateField.getText());
bw.newLine();
bw.write(entryArea.getText());
bw.newLine();
bw.flush();
bw.close();
status.setText("Journal Entry Saved");
else if (businessButton.isSelected())
String file = "Business.txt";
BufferedWriter bw = new BufferedWriter(new FileWriter(file,true));
bw.write("Date: " + dateField.getText());
bw.newLine();
bw.write(entryArea.getText());
bw.newLine();
bw.flush();
bw.close();
status.setText("Journal Entry Saved");
void clearButton_actionPerformed(ActionEvent e) {
dateField.setText("");
entryArea.setText("");
status.setText("");
void saveButton_actionPerformed(ActionEvent e){
try{
saveEntry();
}catch(IOException error){
status.setText("Error: Could not save journal entry");
void personalButton_actionPerformed(ActionEvent e) {
class JournalFrame_clearButton_actionAdapter implements java.awt.event.ActionListener {
JournalFrame adaptee;
JournalFrame_clearButton_actionAdapter(JournalFrame adaptee) {
this.adaptee = adaptee;
public void actionPerformed(ActionEvent e) {
adaptee.clearButton_actionPerformed(e);
class JournalFrame_saveButton_actionAdapter implements java.awt.event.ActionListener {
JournalFrame adaptee;
JournalFrame_saveButton_actionAdapter(JournalFrame adaptee) {
this.adaptee = adaptee;
public void actionPerformed(ActionEvent e) {
adaptee.saveButton_actionPerformed(e);
class JournalFrame_personalButton_actionAdapter implements java.awt.event.ActionListener {
JournalFrame adaptee;
JournalFrame_personalButton_actionAdapter(JournalFrame adaptee) {
this.adaptee = adaptee;
public void actionPerformed(ActionEvent e) {
adaptee.personalButton_actionPerformed(e);
public class JournalApp {
public static void main(String args[])
JournalFrame journal = new JournalFrame();
journal.setVisible(true);
}

Here is the complete code (with crappy indentation) :
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
public class JournalFrame extends JFrame {
    private JLabel dateLabel = new JLabel("Date: ");
    private JTextField dateField = new JTextField(20);
    private JPanel datePanel = new JPanel(new FlowLayout());
    BorderLayout borderLayout1 = new BorderLayout();
    JPanel radioPanel = new JPanel();
    JPanel statusPanel = new JPanel();
    JPanel textAreaPanel = new JPanel();
    JPanel buttonPanel = new JPanel();
    GridLayout gridLayout1 = new GridLayout();
    FlowLayout flowLayout1 = new FlowLayout();
    GridLayout gridLayout2 = new GridLayout();
    GridLayout gridLayout3 = new GridLayout();
    JRadioButton personalButton = new JRadioButton();
    JRadioButton businessButton = new JRadioButton();
    JLabel status = new JLabel();
    JTextArea entryArea = new JTextArea();
    JButton clearButton = new JButton();
    JButton saveButton = new JButton();
    ButtonGroup entryType = new ButtonGroup();
    public JournalFrame(){
        try {
            jbInit();
        catch(Exception e){
            e.printStackTrace();
    private void initWidgets(){
    private void jbInit() throws Exception {
        this.getContentPane().setLayout(borderLayout1);
        radioPanel.setLayout(gridLayout1);
        statusPanel.setLayout(flowLayout1);
        textAreaPanel.setLayout(gridLayout2);
        buttonPanel.setLayout(gridLayout3);
        personalButton.setSelected(true);
        personalButton.setText("Personal");
        personalButton.addActionListener(new JournalFrame_personalButton_actionAdapter(this));
        businessButton.setText("Business");
        status.setText("");
        entryArea.setText("");
        entryArea.setColumns(10);
        entryArea.setLineWrap(true);
        entryArea.setRows(30);
        entryArea.setWrapStyleWord(true);
        clearButton.setPreferredSize(new Dimension(125, 25));
        clearButton.setText("Clear Journal Entry");
        clearButton.addActionListener(new JournalFrame_clearButton_actionAdapter(this));
        saveButton.setText("Save Journal Entry");
        saveButton.addActionListener(new JournalFrame_saveButton_actionAdapter(this));
        this.setTitle("Journal");
        gridLayout3.setColumns(1);
        gridLayout3.setRows(0);
        this.getContentPane().add(datePanel, BorderLayout.NORTH);
        this.getContentPane().add(radioPanel, BorderLayout.WEST);
        this.getContentPane().add(textAreaPanel, BorderLayout.CENTER);
        this.getContentPane().add(buttonPanel, BorderLayout.EAST);
        entryType.add(personalButton);
        entryType.add(businessButton);
        datePanel.add(dateLabel);
        datePanel.add(dateField);
        radioPanel.add(personalButton, null);
        radioPanel.add(businessButton, null);
        textAreaPanel.add(entryArea, null);
        buttonPanel.add(clearButton, null);
        buttonPanel.add(saveButton, null);
        this.getContentPane().add(statusPanel, BorderLayout.SOUTH);
        statusPanel.add(status, null);
        this.pack();
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    private void saveEntry() throws IOException{
        if( personalButton.isSelected()){
            String file = "Personal.txt";
            BufferedWriter bw = new BufferedWriter(new FileWriter(file,true));
            entryArea.getText();
            bw.write("Date: " + dateField.getText());
            bw.newLine();
            bw.write(entryArea.getText());
            bw.newLine();
            bw.flush();
            bw.close();
            status.setText("Journal Entry Saved");
        else if (businessButton.isSelected()){
            String file = "Business.txt";
            BufferedWriter bw = new BufferedWriter(new FileWriter(file,true));
            bw.write("Date: " + dateField.getText());
            bw.newLine();
            bw.write(entryArea.getText());
            bw.newLine();
            bw.flush();
            bw.close();
            status.setText("Journal Entry Saved");
    void clearButton_actionPerformed(ActionEvent e) {
        dateField.setText("");
        entryArea.setText("");
        status.setText("");
    void saveButton_actionPerformed(ActionEvent e){
        try{saveEntry();}catch(IOException error){
            status.setText("Error: Could not save journal entry");
    void personalButton_actionPerformed(ActionEvent e) {
    class JournalFrame_clearButton_actionAdapter implements java.awt.event.ActionListener {
    JournalFrame adaptee;
    JournalFrame_clearButton_actionAdapter(JournalFrame adaptee) {
        this.adaptee = adaptee;
    public void actionPerformed(ActionEvent e) {
        adaptee.clearButton_actionPerformed(e);
class JournalFrame_saveButton_actionAdapter implements java.awt.event.ActionListener {
    JournalFrame adaptee;
    JournalFrame_saveButton_actionAdapter(JournalFrame adaptee) {
        this.adaptee = adaptee;
    public void actionPerformed(ActionEvent e) {
        adaptee.saveButton_actionPerformed(e);
class JournalFrame_personalButton_actionAdapter implements java.awt.event.ActionListener {
    JournalFrame adaptee;
    JournalFrame_personalButton_actionAdapter(JournalFrame adaptee) {
        this.adaptee = adaptee;
    public void actionPerformed(ActionEvent e) {
        adaptee.personalButton_actionPerformed(e);
}BadLands

ActionListener and Inner Class Issue

When I add ".addActionListener()" to buttons and create an inner class to listen/handle the action, my main class does not display the GUI. If I remove the ".addActionListener()" from the buttons and the inner class, the GUI displays. Below is my code. Anyone know what is wrong with my code?
package projects.web;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
public class AppletGUI{
     // JButtons
     JButton addButton = new JButton("Add");
     JButton removeButton = new JButton("Remove");
     JButton saveButton = new JButton("Save");
     JButton cancelButton = new JButton("Cancel");
     // JPanels
     JPanel containerPanel = new JPanel();
     JPanel optionsPanel = new JPanel();
     JPanel thumbnailPanel = new JPanel();
     JPanel selectionPanel = new JPanel();
     // JScrollPane
     JScrollPane thumbnailScroll;
     public AppletGUI(JRootPane topContainer){
          // Add actionListener
          addButton.addActionListener(new ButtonHandler());
          removeButton.addActionListener(new ButtonHandler());
          saveButton.addActionListener(new ButtonHandler());
          cancelButton.addActionListener(new ButtonHandler());
          // Set border layout
          containerPanel.setLayout(new BorderLayout());
          // Add buttons to target panels
          optionsPanel.add(addButton);
          optionsPanel.add(removeButton);
          selectionPanel.add(saveButton);
          selectionPanel.add(cancelButton);
          // Set size and color of thumbnail panel
          thumbnailPanel.setPreferredSize(new Dimension (600,500));
          thumbnailPanel.setBackground(Color.white);
          thumbnailPanel.setBorder(new LineBorder(Color.black));
          // Add thumbnail panel to scrollpane
          thumbnailScroll = new JScrollPane(thumbnailPanel);
          // Set background color of scrollPane
          thumbnailScroll.setBackground(Color.white);
          // Add subpanels to containerPanel
          containerPanel.add(optionsPanel, BorderLayout.NORTH);
          containerPanel.add(thumbnailScroll, BorderLayout.CENTER);
          containerPanel.add(selectionPanel, BorderLayout.SOUTH);
          // Add containerPanel to rootPane's contentPane
          topContainer.getContentPane().add(containerPanel);
     } // end constructor
     class ButtonHandler implements ActionListener{
          public void actionPerformed(ActionEvent event){
               new FileBrowser();
          } // end actionPerformed method
     } // end inner class ActionHandler
} // end AppletGUI class package projects.web;
import java.awt.*;
import java.io.*;
import javax.swing.*;
import javax.swing.filechooser.*;
public class FileBrowser{
     JFileChooser fileChooser = new JFileChooser();
     public FileBrowser(){
          int fileChooserOption = fileChooser.showOpenDialog(null);
     } // end constructor
} // end class fileBrowser

Encephalopathic wrote:
Dan: When it doesn't display, what happens? Do you see any error messages? Also, please take a look at your other thread in this same forum as it has relevance to our conversations in the java-forums.org about whether to add GUIs to root containers or the other way around. /PeteI fiddled with the code some more and it seems that the problem is the inner code. When I changed from the inner class to the main class implementing ActionListener and had the main class implement the actionPerformed method, the GUI displayed and JFileChooser worked as well. I've add this version of the code at the bottom of this message.
To answer your question: When it doesn't display, what happens? -- The web page loads and is blank. And there are no error messages.
I took a look at the other thread is this forum (the one relates to our conversation in the other forum); the problem may be the way I've add the GUI. I'll try it the other way and see what happens.
Thanks,
Dan
package projects.web;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
public class AppletGUI implements ActionListener{
     // JButtons
     JButton addButton = new JButton("Add");
     JButton removeButton = new JButton("Remove");
     JButton saveButton = new JButton("Save");
     JButton cancelButton = new JButton("Cancel");
     // JPanels
     JPanel containerPanel = new JPanel();
     JPanel optionsPanel = new JPanel();
     JPanel thumbnailPanel = new JPanel();
     JPanel selectionPanel = new JPanel();
     // JScrollPane
     JScrollPane thumbnailScroll;
     public AppletGUI(JRootPane topContainer){
          // Add actionListener
          addButton.addActionListener(this);
          removeButton.addActionListener(new ButtonHandler());
          saveButton.addActionListener(new ButtonHandler());
          cancelButton.addActionListener(new ButtonHandler());
          // Set border layout
          containerPanel.setLayout(new BorderLayout());
          // Add buttons to target panels
          optionsPanel.add(addButton);
          optionsPanel.add(removeButton);
          selectionPanel.add(saveButton);
          selectionPanel.add(cancelButton);
          // Set size and color of thumbnail panel
          thumbnailPanel.setPreferredSize(new Dimension (600,500));
          thumbnailPanel.setBackground(Color.white);
          thumbnailPanel.setBorder(new LineBorder(Color.black));
          // Add thumbnail panel to scrollpane
          thumbnailScroll = new JScrollPane(thumbnailPanel);
          // Set background color of scrollPane
          thumbnailScroll.setBackground(Color.white);
          // Add subpanels to containerPanel
          containerPanel.add(optionsPanel, BorderLayout.NORTH);
          containerPanel.add(thumbnailScroll, BorderLayout.CENTER);
          containerPanel.add(selectionPanel, BorderLayout.SOUTH);
          // Add containerPanel to rootPane's contentPane
          topContainer.getContentPane().add(containerPanel);
     } // end constructor
     public void actionPerformed(ActionEvent event){
               new FileBrowser();
          } // end actionPerformed method
     class ButtonHandler implements ActionListener{
          public void actionPerformed(ActionEvent event){
               new FileBrowser();
          } // end actionPerformed method
     } // end inner class ActionHandler
} // end AppletGUI class

Event handling in seperate class

hello... i have a gui w/ a series of combo boxes, text fields, etc. (call this the GUI file)
upon pressing a button, i need to run a series of event handling that will use info from many of these components
i would like to create a separate java file for the button event handling, but need this file to have access to many componets in the GUI file - does anyone know a nice way to do this?

i'm not quite sure how to do that... in my GUI class,
I construct the actuall gui within the constructor..
then i have a simple driver that creates an instance
of class GUI and calls the constructor... how can I
pass a reference of the GUI to the handler in that
scenario??it would be better if you post your code. Some people like me can't just imagine.

Event handling in global class (abap object)

Hello friends
I have 1 problem regarding events in abap object... how to handel an event in global class in se24 .
Regards
Reema jain.
Message was edited by:
        Reema Jain

Hello Reema
The following sample report shows how to handle event in principle (see the § marks)..
The following sample report show customer data ("Header"; KNB1) in the first ALV list and sales areas ("Detail"; KNVV) for the selected customer (event double-click) in the second ALV list.
*& Report ZUS_SDN_TWO_ALV_GRIDS
REPORT zus_sdn_two_alv_grids.
DATA:
gd_okcode        TYPE ui_func,
go_docking       TYPE REF TO cl_gui_docking_container,
go_splitter      TYPE REF TO cl_gui_splitter_container,
go_cell_top      TYPE REF TO cl_gui_container,
go_cell_bottom   TYPE REF TO cl_gui_container,
go_grid1         TYPE REF TO cl_gui_alv_grid,
go_grid2         TYPE REF TO cl_gui_alv_grid,
gs_layout        TYPE lvc_s_layo.
DATA:
gt_knb1          TYPE STANDARD TABLE OF knb1,
gt_knvv          TYPE STANDARD TABLE OF knvv.
"§1. Define and implement event handler method
"     (Here: implemented as static methods of a local class)
*       CLASS lcl_eventhandler DEFINITION
CLASS lcl_eventhandler DEFINITION.
PUBLIC SECTION.
    CLASS-METHODS:
      handle_double_click FOR EVENT double_click OF cl_gui_alv_grid
        IMPORTING
          e_row
          e_column
          es_row_no
          sender.
ENDCLASS.                    "lcl_eventhandler DEFINITION
*       CLASS lcl_eventhandler IMPLEMENTATION
CLASS lcl_eventhandler IMPLEMENTATION.
METHOD handle_double_click.
*   define local data
    DATA:
      ls_knb1      TYPE knb1.
    CHECK ( sender = go_grid1 ).
    READ TABLE gt_knb1 INTO ls_knb1 INDEX e_row-index.
    CHECK ( ls_knb1-kunnr IS NOT INITIAL ).
    CALL METHOD go_grid1->set_current_cell_via_id
      EXPORTING
*        IS_ROW_ID    =
*        IS_COLUMN_ID =
        is_row_no    = es_row_no.
*   Triggers PAI of the dynpro with the specified ok-code
    CALL METHOD cl_gui_cfw=>set_new_ok_code( 'DETAIL' ).
ENDMETHOD.                    "handle_double_click
ENDCLASS.                    "lcl_eventhandler IMPLEMENTATION
START-OF-SELECTION.
SELECT        * FROM knb1 INTO TABLE gt_knb1
         WHERE bukrs = '1000'.
* Create docking container
CREATE OBJECT go_docking
    EXPORTING
      parent                      = cl_gui_container=>screen0
      ratio                       = 90
    EXCEPTIONS
      OTHERS                      = 6.
IF sy-subrc <> 0.
*   MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
*              WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
* Create splitter container
CREATE OBJECT go_splitter
    EXPORTING
      parent            = go_docking
      rows              = 2
      columns           = 1
*      NO_AUTODEF_PROGID_DYNNR =
*      NAME              =
    EXCEPTIONS
      cntl_error        = 1
      cntl_system_error = 2
      OTHERS            = 3.
IF sy-subrc <> 0.
*   MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
*              WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
* Get cell container
CALL METHOD go_splitter->get_container
    EXPORTING
      row       = 1
      column    = 1
    RECEIVING
      container = go_cell_top.
CALL METHOD go_splitter->get_container
    EXPORTING
      row       = 2
      column    = 1
    RECEIVING
      container = go_cell_bottom.
* Create ALV grids
CREATE OBJECT go_grid1
    EXPORTING
      i_parent          = go_cell_top
    EXCEPTIONS
      OTHERS            = 5.
IF sy-subrc <> 0.
*   MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
*              WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
"§2. Set event handler (after creating the ALV instance)
SET HANDLER: lcl_eventhandler=>handle_double_click FOR go_grid1. " Or:
" SET HANDLER: lcl_eventhandler=>handle_double_click FOR all instances.
CREATE OBJECT go_grid2
    EXPORTING
      i_parent          = go_cell_bottom
    EXCEPTIONS
      OTHERS            = 5.
IF sy-subrc <> 0.
*   MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
*              WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
* Display data
gs_layout-grid_title = 'Customers'.
CALL METHOD go_grid1->set_table_for_first_display
    EXPORTING
      i_structure_name = 'KNB1'
      is_layout        = gs_layout
    CHANGING
      it_outtab        = gt_knb1
    EXCEPTIONS
      OTHERS           = 4.
IF sy-subrc <> 0.
*   MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
*              WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
gs_layout-grid_title = 'Customers Details (Sales Areas)'.
CALL METHOD go_grid2->set_table_for_first_display
    EXPORTING
      i_structure_name = 'KNVV'
      is_layout        = gs_layout
    CHANGING
      it_outtab        = gt_knvv " empty !!!
    EXCEPTIONS
      OTHERS           = 4.
IF sy-subrc <> 0.
*   MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
*              WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
* Link the docking container to the target dynpro
CALL METHOD go_docking->link
    EXPORTING
      repid                       = syst-repid
      dynnr                       = '0100'
*      CONTAINER                   =
    EXCEPTIONS
      OTHERS                      = 4.
IF sy-subrc <> 0.
*   MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
*              WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
* NOTE: dynpro does not contain any elements
CALL SCREEN '0100'.
* Flow logic of dynpro (does not contain any dynpro elements):
*PROCESS BEFORE OUTPUT.
* MODULE STATUS_0100.
*PROCESS AFTER INPUT.
* MODULE USER_COMMAND_0100.
END-OF-SELECTION.
*&      Module STATUS_0100 OUTPUT
*       text
MODULE status_0100 OUTPUT.
SET PF-STATUS 'STATUS_0100'. " contains push button "DETAIL"
* SET TITLEBAR 'xxx'.
* Refresh display of detail ALV list
CALL METHOD go_grid2->refresh_table_display
*    EXPORTING
*      IS_STABLE      =
*      I_SOFT_REFRESH =
    EXCEPTIONS
      OTHERS         = 2.
IF sy-subrc <> 0.
*   MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
*              WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
ENDMODULE.                 " STATUS_0100 OUTPUT
*&      Module USER_COMMAND_0100 INPUT
*       text
MODULE user_command_0100 INPUT.
CASE gd_okcode.
    WHEN 'BACK' OR
         'END' OR
         'CANC'.
      SET SCREEN 0. LEAVE SCREEN.
*   User has pushed button "Display Details"
    WHEN 'DETAIL'.
      PERFORM entry_show_details.
    WHEN OTHERS.
ENDCASE.
CLEAR: gd_okcode.
ENDMODULE.                 " USER_COMMAND_0100 INPUT
*&      Form ENTRY_SHOW_DETAILS
*       text
* --> p1        text
* <-- p2        text
FORM entry_show_details .
* define local data
DATA:
    ld_row      TYPE i,
    ls_knb1     TYPE knb1.
CALL METHOD go_grid1->get_current_cell
    IMPORTING
      e_row = ld_row.
READ TABLE gt_knb1 INTO ls_knb1 INDEX ld_row.
CHECK ( syst-subrc = 0 ).
SELECT        * FROM knvv INTO TABLE gt_knvv
         WHERE kunnr = ls_knb1-kunnr.
ENDFORM.                    " ENTRY_SHOW_DETAILS
Regards
Uwe

Event handling without new class

I'm new to Java, so please bear with me.
I'm working with a file management software called Intralink which allows automating tasks by recording keystrokes or writing instructions in Java. A typical recorded script would look like:
// Start Macro Recording
import com.ptc.intralink.client.script.*;*
*import com.ptc.intralink.script.*;
public class newpn2 extends ILIntralinkScript {
ILIntralinkScriptInterface IL = (ILIntralinkScriptInterface)getScriptInterface();
private void run0 () throws Exception {
IL.deselectAll( "WSPI" ); // recorded step: 1
IL.select( "WSPI", "New_Generic/template_sm.prt" ); // recorded step: 2
} // End of run0
public void run () throws Exception {
run0 (); // recorded
} // End of function
} // End Macro RecordingI don't know why but the run0() function has to be called from the run() function. (to clarify that, the run0() can be called from anywhere but all the statements beginning with "IL." are ignored unless it was called from the run() function) I'm trying to write something that uses a dialog box created with JFrame, contains a few combo boxes, and has a JButton to then start the run0() function. This fails because the run0() ends up being called from the actionPerformed class, similar to below.
public void actionPerformed(ActionEvent e)
try
run0();
catch (Exception ex)
System.out.println("Error..." + ex);
}I've tried doing it with an anonymous inner class but the result is the same. Is there any way to detect a button click and act on it within the same function that creates the button?

Vmtr wrote:
I understand what you're suggesting but this would still require me to call the run0() function from within the listener class and (for whatever reason) the "IL." commands are ignored if they are not in a run0() function called directly from a run() function. I'm assuming that this is a quirk built in by the makers of Intralink and I am just trying to find a way around it.Something is happening behind the scenes, something that I don't see evidenced by your current code. Since Intralink is not your class, I guess it is impossible to create a true SSCCE. When I created an SSCCE based on your code, there were no problems:
//import com.ptc.intralink.client.script.*;
//import com.ptc.intralink.script.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
//import javax.swing.border.*;
//import java.util.*;
//import java.text.*;
//import java.io.*;
//import java.sql.*;
//import com.ptc.intralink.ila.*;
public class forum extends ILIntralinkScript
ILIntralinkScriptInterface IL = (ILIntralinkScriptInterface) getScriptInterface();
private void run0() throws Exception
    JOptionPane.showMessageDialog(null, "In the run0 function!");
    IL.openWindow("Workspace", null, null); // recorded step: 1
    IL.selectTree("FTLOCALDB", "Local Database"); // recorded step: 2
} // End of run0
public void run() //throws Exception
    JButton button1 = new JButton("Done");
    button1.setPreferredSize(new java.awt.Dimension(310, 18));
    JFrame f = new JFrame("New Part Number");
    // add this so it exits nice:
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setSize(360, 300);
    f.setResizable(false);
    Container content = f.getContentPane();
    content.add(button1);
    button1.addActionListener(new ActionListener()
      public void actionPerformed(ActionEvent ee)
        try
          run0();
        catch (Exception ex)
          System.out.println("Error..." + ex);
          ex.printStackTrace();
    f.setVisible(true);
// get this all to run
public static void main(String[] args)
    SwingUtilities.invokeLater(new forum());
// dummy classes to allow for compilation
abstract class ILIntralinkScript implements Runnable
public ILIntralinkScriptInterface getScriptInterface()
    return new ILIntralinkScriptInterface();
class ILIntralinkScriptInterface
public void openWindow(String string, Object object, Object object2)
    JOptionPane.showMessageDialog(null, "in method openWindow(" + string + ", " + object + ", "
        + object2 + ")");
public void selectTree(String string, String string2)
    JOptionPane.showMessageDialog(null, "in method selectTree(" + string + " ," + string2 + ")");
}

Problem with Outer and Inner Classes....or better way?

Right now I'm trying to create an Inner class.
My .java file compiles ok, and I create my jar file too.
But when I try to instantiate the Inner class, it fails:
java.lang.NoClassDefFoundError: com/myco/vlXML/vlXML$vlDocument.
Here's the class code:
public class vlXML{
    private ArrayList myDocList=new ArrayList(); //holds documents
    public vlXML(){
    private class vlDocument{
        public vlDocument(){
        //stuff goes here
    public vlDocument vlDOC(){
        return new vlDocument();
    public void addDocument(){
        vlXML xxx=new vlXML();
        vlDocument myDoc=xxx.vlDOC();
        myDocList.add(myDoc);
    public int getNumDocs(){
        return myDocList.size();
}Then, from a jsp page, I call:
vlXML junk1=new vlXML();
junk1.addDocument();...and get the error...
Can someone help me figure out why it's failing?
Thanks....

You nailed it - thanks....(duh!)
While I have your attention, if you don't mind, I have another question.
I'm creating a Class (outer) that allows my users to write a specific XML file (according to my own schema).
Within the XML file, they can have multiple instances of certain tags, like "Document". "Document"s can have multiple fields.
Since I don't know how many "Documents" they may want, I was planning on using an Inner Class of "Document", and then simply letting them "add" as many as necessary (thus the original code posted here).
Does that seem like an efficient (logical/reasonable) methodology,
or is there there something better?
Thanks Again...

Problem with final variables and inner classes (JDK1.1.8)

When using JDK1.1.8, I came up with following:
public class Outer
    protected final int i;
    protected Inner inner = null;
    public Outer(int value)
        i = value;
        inner = new Inner();
        inner.foo();
    protected class Inner
        public void foo()
            System.out.println(i);
}causing this:
Outer.java:6: Blank final variable 'i' may not have been initialized. It must be assigned a value in an initializer, or in every constructor.
public Outer(int value)
^
1 error
With JDK 1.3 this works just fine, as it does with 1.1.8 if
1) I don't use inner class, or
2) I assign the value in initializer, or
3) I leave the keyword final away.
and none of these is actually an option for me, neither using a newer JDK, if only there is another way to solve this.
Reasons why I am trying to do this:
1) I can't use a newer JDK
2) I want to be able to assign the variables value in constructor
3) I want to prevent anyone (including myself ;)) from changing the value in other parts of the class (yes, the code above is just to give you the idea, not the whole code)
4) I must be able to use inner classes
So, does anyone have a suggestion how to solve this problem of mine? Or can someone say that this is a JDK 1.1.8 feature, and that I just have to live with it? In that case, sticking to solution 3 is probably the best alternative here, at least for me (and hope that no-one will change the variables value). Or is it crappy planning..?

You cannot use a final field if you do not
initialize it at the time of declaration. So yes,
your design is invalid.Sorry if I am being a bit too stubborn or something. :) I am just honestly a bit puzzled, since... If I cannot use a final field in an aforementioned situation, why does following work? (JDK 1.3.1 on Linux)
public class Outer {
        protected final String str;
        public Outer(String paramStr) {
                str = paramStr;
                Inner in = new Inner();
                in.foo();
        public void foo() {
                System.out.println("Outer.foo(): " + str);
        public static void main( String args[] ) {
                String param = new String("This is test.");
                Outer outer = new Outer(param);
                outer.foo();
        protected class Inner {
                public void foo() {
                        System.out.println("Inner.foo(): " + str);
} producing the following:
[1:39] % javac Outer.java
[1:39] % java Outer
Inner.foo(): This is test.
Outer.foo(): This is test.
Is this then an "undocumented feature", working even though it shouldn't work?
However, I assume you could
get by with eliminating the final field and simply
passing the value directly to the Inner class's
constructor. if not, you'll have to rethink larger
aspects of your design.I guess this is the way it must be done.
Jussi

Interface and Inner Class

Hi,
In interface we can't provide method body.
but we can provide method body like this,
public interface TestInterface {
     public class Add {
          public int add() {
               return 100;
what is the logic behind Inner Class inside interface.
plz help.Thanks in advance.

there isn't really any logic to it, it's just something that's semantically possible. there wasn't a conscious decision to allow this, it's just a by-product of the enclosing types mechanism, and while it wouldn't be a good idea to do this, there's no technical reason why it shouldn't be possible, either

Generics and inner classes?

How can I say my inner class uses the same type as it's genericised host class?
Should I just not declare a "generic" type in the inner class?
The code
public class LinkedList<E> implements java.util.List<E>
... code omitted for brevity ...
   * An internal implementation of java.util.Iterator.
private class Iterator<E> implements java.util.Iterator<E> {
    protected Node<E> current;
    public Iterator() {
      this.current = head; // error here
... code omitted for brevity ...
produces the compiler error
C:\Java\home\src\linkedlist\LinkedList.java:59: incompatible types
found   : linkedlist.LinkedList.Node<E>
required: linkedlist.LinkedList.Node<E>
      this.current = head;
                     ^I understand the meaning of the compiler error... it's effectively saying that "E" is not the same type within in the Iterator class as it is in the parent LinkedList class... What I don't understand is how to make E the same type within the Iterator... if I just leave the <E> off of Iterator<E> then it throws "unchecked operation" warnings... do I just have to put up with these warnings... but no that can't be right because java.util.LinkedList has an iterator and it's not throwing unchecked operation compiler warnings... so there has to be a way...
Thanx all. Keith.

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.

Subclassing and inner classes

Hi there,
I have an existing class "A", supplied by a third party, that contains a private inner class "I".
I have subclassed "A" to a new class "B" to add new functionality, and I also want to replace the inner class "I" with new behaviour. The inner class "I" is invoked by methods within "A" that I have not overridden in "B". Replacing "I" appears to be impossible under these circumstances.
My initial experiment was to create a new inner class "I" within "B" with the same name and signature as the "I" defined within "A", so...
Class B extends A {
private class I {}
The code that invokes "I" is still within "A" and so my version of the "I" class is ignored, and the original "I" is invoked instead.
Let's be clear about this, I am not surprised by this behaviour, I'm just wondering if there is any way I can get my "I" invoked by the methods in "A". If that is indeed impossible I will have to write new methods in "B" that override the invoking methods in "A".
I did a search on the forums using the title I gave this topic, and got some fairly close hits, but nothing seemed to quite answer my question.
Hope that all made sense. Thanks for any help.
Regards,
Tim

When a class is compiled, all the references are resolved. So in the 'A' class file, a call to method someMethod() in inner class I is resolved as
some.package.A$I.someMethod()
Short of replacing the A$I class file, I don't know what you can do. (I think)

Event handling and inner classes

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