I'm currently making a reading app in Java, and this is my main menu.
What I want is that when I press the bottom button after selecting a book another window with the book opens. What I did now is a function that will open the other window while closing the one I'm currently in to free a little bit of memory.
I first close the current window after retrieving the necessary information from it (the index of the book) like this:
btnOuvrirLeLivre.addSelectionListener(new SelectionAdapter() {
#Override
public void widgetSelected(SelectionEvent e) {
int index = list.getSelectionIndex();
LiseuseController controller = new LiseuseController(null, null);
parent.dispose();
controller.viewBookController(index);
}
});
(I'm using the MVC method for my project), parent is just the composite used to open the frame.
public void viewBookController(int index) {
Display displayBook = new Display();
Shell shellBook = new Shell(displayBook);
shellBook.setLayout(new GridLayout(1, false));
index += 250;
LiseuseView lecture = new LiseuseView(shellBook, SWT.NONE, index);
shellBook.pack();
shellBook.open();
while(!shellBook.isDisposed()) {
if(!displayBook.readAndDispatch())
displayBook.sleep();
}
displayBook.dispose();
}
The index is just the book's number in my database, everything should be fine but I get this error when I do this after pressing the button to open the book:
Exception in thread "main" org.eclipse.swt.SWTException: Invalid thread access
at org.eclipse.swt.SWT.error(SWT.java:4875)
at org.eclipse.swt.SWT.error(SWT.java:4790)
at org.eclipse.swt.SWT.error(SWT.java:4761)
at org.eclipse.swt.widgets.Display.checkDisplay(Display.java:824)
at org.eclipse.swt.widgets.Display.create(Display.java:887)
at org.eclipse.swt.graphics.Device.<init>(Device.java:126)
at org.eclipse.swt.widgets.Display.<init>(Display.java:563)
at org.eclipse.swt.widgets.Display.<init>(Display.java:554)
at Controller.LiseuseController.viewBookController(LiseuseController.java:133)
at View.LiseuseHome$4.widgetSelected(LiseuseHome.java:81)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:252)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:89)
at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4209)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1037)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4026)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3626)
at Controller.LiseuseController.viewController(LiseuseController.java:126)
at Main.Main.main(Main.java:59)
(LiseuseController.java:133) contains "Display displayBook = new Display();"
And (LiseuseController.java:126) contains
if(!display.readAndDispatch())
display.sleep();
This is from the other function used to open the first window.
I don't really understand what is causing this error and I can't just put one in "visible" and the other one "invisible" like if I'm using Jframe because the 2 windows are on 2 different .java files.
Do you have any idea on how to fix this?
From the API documentation of org.eclipse.swt.widgets.Display
Applications which are built with SWT will almost always require only
a single display. In particular, some platforms which SWT supports
will not allow more than one active display. In other words, some
platforms do not support creating a new display if one already exists
that has not been sent the dispose() message.
You should therefore adapt your application to use only one instance of Display. Since the class LiceuseController already manages opening the initial window and the supplementary window(s), it seems fitting for it to manage an instance of Display for both uses.
This instance should be created at the application's start, maintained by the LiceuseController class and finally disposed when the application shuts down.
Another problem is that none of the methods in LiceuseController actually returns. As you can see from the stack trace, Display.readAndDispatch from LiseuseController.viewController is still active when you are creating the new window. I guess you also want to reopen the original window when the supplementary window is closed. Opening and closing windows in this manner will, however, endlessly increase your call stack until you end up with a StackOverflowException.
Instead, the LiceuseController should be able to create windows without outside interference. Therefore, instead of actively calling a method in the controller class to open another window, the listener should only tell the controller what window it should open next when the current window was closed.
An example could look like
public enum WindowType {
MAIN, BOOK, NONE
}
public class LiceuseController {
Display display;
WindowType nextToOpen = WindowType.MAIN;
public LiceuseController() {
display = new Display();
}
public void setNextToOpen(WindowType value) {
nextToOpen = value;
}
public void run() {
for (boolean run = true; run;) {
switch(nextToOpen) {
case MAIN:
viewController();
break;
case BOOK:
viewBookController();
break;
case NONE:
run = false;
break;
default:
throw new RuntimeException("unexpected enum constant");
}
}
/*
* Depending on how you want to manage the instance of this class,
* you could also extract this into a separate method.
*/
display.dispose();
}
private void viewController() {
// open main window using 'display'
}
private void viewBookController() {
// open book window using 'display'
}
}
so that a listener only needs to call LiceuseController.setNextToOpen and then close the current window. This will cause either viewController or viewBookController to return after which the loop will reenter and open the requested window. To shut down the application, call setNextToOpen with WindowType.NONE.
If you have ever used Window.alert("msg"); API in GWT to show popup, I am not sure but the call to this API pauses the code execution until a user action is taken (cliking the ok button), Simillar to that i have created a custom popup, when it is shown i don't want the code to execute further till any user input in received on the popup, How can i pause the code execution further?
Assume :-
//Some Code
MY Popup (Here i want to wait till a user action is received.)
//Some code
I read somewhere to use Synchronized key word but that didn't work either,Do you have answer to this. How GWT compiler sees "Synchronized" keyword does it ignores the keyword?
Create something like a ConfirmCallBack that you fire when the "OK" button (or whatever) is clicked in the popuppanel.
//method in your own popup class
public static void confirm(String message, ConfirmCallBack confirmCallBack)
{
Button confirmButton = new Button(confirmButtonText, event ->
{
confirmCallBack.callback(true);
//hide popup
});
}
Than also have the ConfirmCallBack interface like
public interface ConfirmCallBack
{
void callback(boolean result);
}
Then call your own popup like
MyPopup.confirm("Hello world", result ->
{
if (result)
{
//my code to be executed after clicking the ok button
}
}
I have some problems with use of ContractNet (Interaction Protocol) and GUI with the use of JADE multiagent framework.
In particular, in the override of handlePropose method.
I know that my problem comes from the use of a GUI. Let me explain:
My agent (Initiator) uses a first GUI and, after a click, the
conversation begins with a second agent (Responder). According to the
Protocol, the Initiator has thus sent a CFP to Responder. The agent
Responder responds with a PROPOSE that contains different data.
Since here, everything ok. Now...
I wish that the agent Initiator, BEFORE returning a reply, may examine
the data ... ie publish them on a JTable, for the user! The user will
examine the proposal via GUI and will choose if to accept or not, by
click on a button.
If accept, the Initiator send ACCEPT_PROPOSAL.
If not accept, the Initiator send REJECT_PROPOSAL.
This should be done in the method handleProposal. This is my code:
#Override
protected void handlePropose(final ACLMessage propose, final Vector acceptances) {
try {
System.out.println("Agent "+getLocalName()
+": receive PROPOSE from "+propose.getSender().getLocalName());
final ACLMessage reply = propose.createReply();
Vector<Goods> goods = (Vector<Goods>) propose.getContentObject();
// the JTable's GUI for visualize the list of data:
final GoodsChoiceBox gcb = new GoodsChoiceBox(propose.getSender().getName(), goods);
// the problem:
gcb.getExecuteJButton().addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
reply.setPerformative(ACLMessage.ACCEPT_PROPOSAL);
System.out.println("Agent "+getLocalName()+": send ACCEPT PROPOSAL ");
acceptances.addElement(reply);
}
});
// similar case, but for REJECT:
// gcb.getAbortJButton().addActionListener(... bla bla
gcb.setVisible(true);
} catch (UnreadableException e){
e.printStackTrace();
}
}
..... But, obviously, does not work.
In the Initiator agent, the ContractNet behaviour is aborted... so also handleInform, handleRefuse and handleFailure (for handle the answers) do not work.
The Initiator's principal GUI is blocked. And other problems...
Instead, if I do this (WITHOUT JButton, another GUI and ActionListener):
#Override
protected void handlePropose(final ACLMessage propose, final Vector acceptances) {
try {
System.out.println("Agent "+getLocalName()
+": received PROPOSE from "+propose.getSender().getLocalName());
final ACLMessage reply = propose.createReply();
Vector<Goods> goods = (Vector<Goods>) propose.getContentObject();
// the JTable's GUI for visualize the list of data:
final GoodsChoiceBox gcb = new GoodsChoiceBox(propose.getSender().getName(), goods);
reply.setPerformative(ACLMessage.ACCEPT_PROPOSAL);
System.out.println("Agente "+getLocalName()+": ACCEPT PROPOSAL di "+propose.getSender().getLocalName());
acceptances.addElement(reply);
} catch (UnreadableException e){
e.printStackTrace();
}
}
.... works.
I know that the problem is the ActionListener and its multithread nature.
But I need the GUI there.
How can I fix?
I try to answer myself. I'm not sure it's the best solution, but certainly works.
Note that before coming to this solution I am well documented with the guides and tutorials found (on http://jade.tilab.com/), and confronting myself with other
JADE developers (in mailing lists http://jade.tilab.com/pipermail/jade-develop/)
The answer is complicated, so I'll try to be exhaustive.
In my project I have to deal with two different types of agents.
The ShipperAgent, which represents one shipper: it keeps track of the vehicles owned by the shipper, those available, and the goods "reserved" from it.
The BuyerAgent, which represents customers (or buyers): each customer has a list of goods that want to move from point A to point B.
The two agents are registered to the yellow pages service.
In ShipperAgent, clicking on the "SEARCH" button you start a search: start a Contract Net Interaction Protocol.
Explain the Contract Net Interaction Protocol and my case
In the standard FIPA: http://www.fipa.org/specs/fipa00029/SC00029H.html
In JADE guide can be found here: http://jade.tilab.com/doc/programmersguide.pdf (p. 35)
Further on you will notice the changes that I had to take.
The ShipperAgent sends CFP each BuyerAgent.
Each BuyerAgent:
2.1 if he has goods, send a PROPOSE to ShipperAgent.
2.2 if does not have the goods, send a REFUSE to ShipperAgent. And for buyer, the protocol ends.
Since here is easy. With the sniffer, we can observe:
Now:
The ShipperAgent:
3.1 receives one or more PROPOSE by buyers, and displays (see image below).
3.2 if it receives the REFUSE (or does not receive anything after a certain time), ending communication with those buyer.
Here's how the Shipper graphically displays the proposals:
Now it's up to the user to choose which goods wants and what not.
To achieve this, I had to create some kind of "internal communication" to the agent himself: the GUI (in 3.1), once clicked Execute, sends a message to the agent. It may seem inelegant, but it seems to be the only way to not crash the protocol side ShipperAgent.
The ShipperAgent:
4.1 if the user has selected one or more goods proposals (and click Execute), sends to the corresponding BuyerAgent an ACCEPT_PROPOSAL, where specific goods that want to (a subset of the previous proposal).
4.2 if the user does not select any good (or click on Cancel), sends to the corresponding BuyerAgent an REJECT_PROPOSAL. Ends communication to that buyer.
The BuyerAgent:
5.1 if receives an ACCEPT_PROPOSAL, check that the goods are still available (any other shippers could have them "reserved" in the meanwhile) and, if so, sends an INFORM.
5.2 if receives an ACCEPT_PROPOSAL ma one or more goods are no longer available, sends FAILURE.
5.3 if it receives an REJECT_PROPOSAL, ends communication with the ShipperAgent.
In brief this (for example):
The code
BuyerAgent.java
I create a dispatcher who is always ready to receive the CFP. As soon as it receives and start protocol, buyer-side: start SearchJobResponder.
/*
* ...
*/
final MessageTemplate template = MessageTemplate.and(
MessageTemplate.MatchProtocol(FIPANames.InteractionProtocol.FIPA_CONTRACT_NET),
MessageTemplate.MatchPerformative(ACLMessage.CFP) );
// SSResponderDispatcher:
SSResponderDispatcher dispatcher = new SSResponderDispatcher(this, template) {
BuyerAgent b = (BuyerAgent) this.myAgent;
protected Behaviour createResponder(ACLMessage initiationMsg) {
// SearchJobResponder for single cfp:
return new SearchJobResponder(b, initiationMsg);
}
};
addBehaviour(dispatcher);
/*
* ...
*/
ShipperAgent.java
Search all buyer, creates a CFP and start the protocol, shipper-side: start SearchJobInitiator.
/*
* ...
*/
ACLMessage cfp = new ACLMessage(ACLMessage.CFP);
AID[] buyerAgents = searchBuyers(); // search all buyerAgents
for (AID buyer : buyerAgents)
cfp.addReceiver(buyer);
addBehaviour(new SearchJobInitiator(this, cfp));
/*
* ...
*/
SearchJobInitiator.java
This was the hard part...
/*
* ...
*/
public class SearchJobInitiator extends ContractNetInitiator {
ShipperAgent shipperAgent;
public SearchJobInitiator(ShipperAgent a, ACLMessage cfp) {
super(a, cfp);
shipperAgent=a;
// Very important:
registerHandleAllResponses(new HandleProposes());
}
#Override
protected Vector<?> prepareCfps(ACLMessage cfp) {
long now = System.currentTimeMillis();
cfp.setConversationId("contractNet-by-"
+shipperAgent.getAID().getLocalName()+now);
cfp.setContent("Fammi delle proposte di lavoro");
/*
* filtering...
*/
cfp.setProtocol(FIPANames.InteractionProtocol.FIPA_CONTRACT_NET);
cfp.setReplyByDate(new Date(now+10000));
//cfp.setReplyWith("cfp"+System.currentTimeMillis()) //useless, is overwrited at the end
return super.prepareCfps(cfp);
}
//inner class for handling a single proposal
public class HandleProposes extends Behaviour {
private static final long serialVersionUID = 1L;
private Vector<ACLMessage> proposes;
private Vector<ACLMessage> acceptances;
private int numberOfProposes;
public void onStart() {
proposes = (Vector<ACLMessage>) getDataStore().get(ALL_RESPONSES_KEY);
acceptances = (Vector<ACLMessage>) getDataStore().get(ALL_ACCEPTANCES_KEY);
numberOfProposes=proposes.size();
for (Iterator I=proposes.iterator(); I.hasNext();) {
ACLMessage propose = (ACLMessage) I.next();
// Very important:
if (propose.getPerformative()==ACLMessage.PROPOSE)
myAgent.addBehaviour(new HandleSinglePropose(propose, acceptances));
else
numberOfProposes--;
}
}
public void action() {
if (!done())
block();
}
public boolean done() {
return (acceptances.size()==numberOfProposes);
}
/*
* Inner class for handle a single proposal and display it:
*/
public class HandleSinglePropose extends Behaviour {
private ACLMessage propose;
private Vector<ACLMessage> acceptances;
private boolean finish=false;
public HandleSinglePropose (ACLMessage propose, Vector<ACLMessage> acceptances) {
this.propose=propose;
this.acceptances=acceptances;
// This is GUI in 3.1 point
GoodsChoiceBox gcb = new GoodsChoiceBox(shipperAgent, this, propose); // fill the JTable
gcb.setVisible(true);
}
#Override
public void action() {
MessageTemplate mt = MessageTemplate.and(
MessageTemplate.MatchSender(shipperAgent.getAID()),
MessageTemplate.and(
MessageTemplate.MatchReplyWith("response"+propose.getReplyWith()),
MessageTemplate.or(
MessageTemplate.MatchPerformative(ACLMessage.ACCEPT_PROPOSAL),
MessageTemplate.MatchPerformative(ACLMessage.REJECT_PROPOSAL)
) ) ) ;
// Read data from GUI. The user accept or reject:
ACLMessage decisionFromGUI = shipperAgent.receive(mt);
if (decisionFromGUI != null) {
ACLMessage reply = propose.createReply();
// bla bla...
finish=true;
HandleProposes.this.restart();
} else {
block();
}
}
public boolean done() {
return finish;
}
public void handleChoice(ACLMessage propose, boolean bool, Vector<Goods> selectedGoods) {
ACLMessage reply;
if (bool){
reply = new ACLMessage(ACLMessage.ACCEPT_PROPOSAL);
//...
} else {
reply = new ACLMessage(ACLMessage.REJECT_PROPOSAL);
//...
}
reply.addReceiver(shipperAgent.getAID());
reply.setReplyWith("response"+propose.getReplyWith());
shipperAgent.send(reply);
}
} // closes HandleSinglePropose
} // closes HandleProposes
}
SearchJobResponder.java
The responder is simple. The only thing of note: I extends SSContractNetResponder, don't extends ContractNetResponder.
public class SearchJobResponder extends SSContractNetResponder {
BuyerAgent buyerAgent;
public SearchJobResponder(BuyerAgent a, ACLMessage cfp) {
super(a, cfp);
buyerAgent = a;
}
/*
* override methods...
*/
}
GoodsChoiceBox.java
The GUI for show the proposals...
public GoodsChoiceBox(final Agent agent, final HandleSinglePropose behaviour, final ACLMessage propose){
/*
* graphics stuff
*/
// if goods selected and press Execute
behaviour.handleChoice(propose,true,selectedGoods);
//else
behaviour.handleChoice(propose,false,null);
/*
* bla bla
*/
}
I know, I have dwelt much, but I did not know how else to explain.
However, now my project work. But I'm open to any suggestions.
I often run into this problems of this sort. These are Finite State machine behaviours so you should be able to pause and resume a behavior but I'm not sure how. What I do is create two separate Interaction behaviors on the initiator side and one on the responder side.
Initiator Responder
| |
| |
| First behaviour |The responder only has 1 behaviour
|| CFP-> ||
|| <-Proposal ||
| ||
| Second behaviour ||
|| Accept prop-> ||
|| <-Response ||
| |
Two points to remember
(1)
Make sure that you save the conversationID
msgRecieved.getConversationID
from the first behaviour and use it in the second Behaviour.
msg.setConversationID().
(2)
The second behavior is another Contract net initiator but in prepareCFPs method set MESSAGE performative to accept proposal
class ContractServiceList extends ContractNetInitiator
{
protected Vector prepareCfps(ACLMessage cfp) {
ACLmessage AP= new ACLmessage(ACLmessage.ACCEPT_PROPOSAL)
.....
These things are hard to explain so I tried to attached a picture but have 2 little rep points.
I now have enough rep points to attach the picture which I am doing.
I just realized that there is another solution to this problem. The second solution involves using ChildBehaviours and data stores. A child behaviour can be initiated pausing the parent behaviour. The parent behaviour must then be resumed one the child is complete.
I'm attaching a pic to better explain this interaction.
So at point A in your CNI (ContractNetInitiator) parent behaviour you want to initiate the Child behaviour. You would do this by using the CNI.registerHandlePropose(new Childbehaviour).
This is what the setup() method should look like:
protected void setup()
{
ContractNetInitiator parentBehave= new ContractNetInitiator (null, null, GlobDataStore);
ContractNetInitiator.registerHandlePropose(new ChildBehavoiur (GlobDataStore));
addBehaviour(CNI);
}
In you Child behaviour you will have to check the data from the parent (GlobDataStore) and return a message to be passed back. Code to follow:
class ChildBehaviour extends OneShotBehaviour{
#Override
public void action() {
//evaluate globalestore here;
ACLMessage CNIresponse=new ACLMessage();
if(true)
{
storeNotification(ACLMessage.ACCEPT_PROPOSAL, CNIresponse);
}
else
{
storeNotification(ACLMessage.REJECT_PROPOSAL, CNIresponse);
}
}
public void storeNotification(int performative, ACLMessage original)
{
// Retrieve the incoming request from the DataStore
String incomingCFPkey = (String) ((ContractNetResponder) parent).CFP_KEY;
incomingCFPkey = (String) ((ContractNetResponder) parent).CFP_KEY;
ACLMessage incomingCFP = (ACLMessage) getDataStore().get(incomingCFPkey);
// Prepare the notification to the request originator and store it in the DataStore
ACLMessage notification = incomingCFP.createReply();
notification.setPerformative(performative);
notification.setContent(original.getContent());
String notificationkey = (String) ((ContractNetResponder) parent).PROPOSE_KEY;
getDataStore().put(notificationkey, notification);
}
}
I want to make a confirm function in java just like a alert in javascript.
Example javascript code:
var a = prompt("");
In java i have a function that returns a string with a dialog box input;
public static boolean log ;
public String value;
public String androidPrompt(){
log = true;
showMyDialog();
while(log){
}
return value;
}
public void showMyDialog(){
log= false;
value = //inputed value from dialog;
}
But my application don't respond. What should i do. I want to pause
androidPrompt() while showMyDialog() is not done. and when showMyDialog()
is done androidPrompt() function will resume and return the value
Example javascript code: var a = prompt("");
Android does not support that sort of blocking UI call. Instead, use listeners to notify something within your app when the user has accepted the dialog (e.g., pressed the OK button).
I have a Swing GUI where I am restricting the user registration so that the username and the password cannot be the same. I am using JoptionPane for the task with the following code:
public void actionPerformed(ActionEvent e) {
String username = tuser.getText();
String password1 = pass1.getText();
String password2 = pass2.getText();
String workclass = wclass.getText();
Connection conn = null;
try {
if(username.equalsIgnoreCase(password1)) {
JOptionPane.showMessageDialog(null,
"Username and Password Cannot be the same. Click OK to Continue",
"Error", JOptionPane.ERROR_MESSAGE);
System.exit(0);
}
...
The problem is that I had to use System.exit(0); without it, the next code was getting executed. Even after the JOptionPane poped up, the registration was succeeding. I do not need the system to exit, but I need the user to be kept on the registration page after the validation. What is the best way to do this? Is there other convenient ways of doing this rather than using the JOptionPane?
Replace
System.exit(0);
with
return;
if you do not want the rest of the method to be performed
You need to place your code within endless loop, and break it upon successful result. Something like:
while(true)
{
// get input from user
if(vlaidInput) break;
}
place that next code into else part may be it works
if(username.equalsIgnoreCase(password1))
{
JOptionPane.showMessageDialog(null, "Username and Password Cannot be the same. Click OK to Continue","Error",JOptionPane.ERROR_MESSAGE);
}
else
{
//place that next code
// username and password not equals, then it will execute the code
}
First of all, it is best if the UI and business logic (in this case, validation) are separated. Have them separate sort of suggest a better way of handling interaction on its own. Thus, it makes sense to create a separate class UserValidation with method boolean isValid(). Something like this:
public class UserValidation {
private final String name;
private final String passwd;
private final String passwdRpt;
public UserValidation(final String name, final String passwd, final String passwdRpt) {
this.name = name;
this.passwd = passwd;
this.passwdRpt = passwdRpt;
}
public boolean isValid() {
// do your validation logic and return true if successful, or false otherwise
}
}
Then the action code would look like this:
public void actionPerformed(ActionEvent e) {
if (new UserValidation(tuser.getText(), pass1.getText(), pass2.getText()).isValid()) {
// do everything needed is validation passes, which should include closing of the frame of dialog used for entering credentials.
}
// else update the UI with appropriate error message -- the dialog would not close by itself and would keep prompting user for a valid entry
}
The suggested approach gives you a way to easily unit test the validation logic and use it in different situations. Please also note that if the logic in method isValid() is heavy than it should be executed by a SwingWorker. The invocation of SwingWorker is the responsibility of the action (i.e. UI) logic.