I'm trying to write a simple application in Java that will communicate with an USB device. The USB device is made by me using a Microchip Microcontroller. The communication is rather simple, since the USB device is from the HID Class, arrays of 64 bytes are exchanged between the computer and the device.
My program finds the device based on the product ID and the vendor ID, can write and read 64 bytes, but now I would like to detect when the device is connected or disconnected from the computer.
As I've seen in a C# program provided by Microchip as an example application, the WndProc method is overriden and the WM_DEVICECHANGE message is handled. My question is how can this be done in Java using JNA, how can I override the WindowProc Method and handle messages, if this is possible at all :), but I hope it is :D
Thanks in advance for the answers.
Gabor.
I finally managed to solve the problem :) And I found the following solution:
First extend the User32 interface in the following way
public interface MyUser32 extends User32 {
public static final MyUser32 MYINSTANCE = (MyUser32) Native.loadLibrary("user32", MyUser32.class, W32APIOptions.UNICODE_OPTIONS);
/**
* Sets a new address for the window procedure (value to be set).
*/
public static final int GWLP_WNDPROC = -4;
/**
* Changes an attribute of the specified window
* #param hWnd A handle to the window
* #param nIndex The zero-based offset to the value to be set.
* #param callback The callback function for the value to be set.
*/
public int SetWindowLong(WinDef.HWND hWnd, int nIndex, Callback callback);
}
Then extend the WinUser interface with the Windows Message code that you need, in my case this is the WM_DEVICECHANGE, because I want to check I the USB Device was attached or detached from the computer.
public interface MyWinUser extends WinUser {
/**
* Notifies an application of a change to the hardware configuration of a device or the computer.
*/
public static final int WM_DEVICECHANGE = 0x0219;
}
Then create an interface with the callback function, which will actually be my WndProc function.
//Create the callback interface
public interface MyListener extends StdCallCallback {
public LRESULT callback(HWND hWnd, int uMsg, WPARAM uParam, LPARAM lParam);
}
public MyListener listener = new MyListener()
{
public LRESULT callback(HWND hWnd, int uMsg, WPARAM uParam, LPARAM lParam)
{
if (uMsg == MyWinUser.WM_DEVICECHANGE)
{
// TODO Check If my device was attached or detached
return new LRESULT(1);
}
return new LRESULT(0);
}
};
And then somewhere in the code of the JFrame where you initialize things add the new address for the window procedure with the SetWindowLong function:
// Get Handle to current window
HWND hWnd = new HWND();
hWnd.setPointer(Native.getWindowPointer(this));
MyUser32.MYINSTANCE.SetWindowLong(hWnd, MyUser32.GWLP_WNDPROC, listener);
This code works nicely, but I have some doubts regarding one thing. I'm not sure if the return value of the callback function is correct. I've read in the MSDN that after handling a WM_DEVICECHANGE message the callback function should return true and I'm not sure that the value i'm currently returning is the one expected by the system, so any suggestions are welcome.
If anyone is interested in the whole code I've written for the HID communication just ask, I would be more than happy to help :)
Cheers,
Gabor.
If you don't have an existing window handle you have to create your own window first. And when you create a new window you also have to manage its message pump. Here's an example on how you can do this. JNA's own example code could also be very useful.
Thread thread;
HWND hWnd;
static final int WM_NCCREATE = 0x0081;
void start() {
thread = new Thread(this::myThread);
thread.start();
}
void stop() {
User32.INSTANCE.PostMessage(hWnd, User32.WM_QUIT, null, null);
}
WindowProc callback = new WindowProc() {
#Override
public LRESULT callback(HWND hWnd, int uMsg, WPARAM wParam, LPARAM lParam) {
switch (uMsg) {
case WM_NCCREATE:
return new LRESULT(1);
case User32.WM_DEVICECHANGE:
return new LRESULT(1);
default:
return new LRESULT(0);
}
}
};
void myThread() {
WString className = new WString("myclass");
WNDCLASSEX wx = new WNDCLASSEX();
wx.clear();
wx.lpszClassName = className;
wx.lpfnWndProc = callback;
if (User32.INSTANCE.RegisterClassEx(wx).intValue() != 0) {
hWnd = User32.INSTANCE.CreateWindowEx(0, className, null, 0, 0, 0, 0, 0, null, null, null, null);
WinUser.MSG msg = new WinUser.MSG();
msg.clear();
while (User32.INSTANCE.GetMessage(msg, hWnd, 0, 0) > 0) {
User32.INSTANCE.TranslateMessage(msg);
User32.INSTANCE.DispatchMessage(msg);
}
}
}
You can create COM DLL or OCX of your C# program and use it in the java code. If you create application.
Use JACOB OR JCOM
It will be a bridge between Java and COM Object. Other option is you can use JNI to communicate with DLL and OCX.
The solution I posted previously has some problems, unfortunately :(
Since it overrides the WndProc of the window, the controls I added to my Frame weren't working (not surprisingly, because no paint, repaint, etc. messages were handled). Then I realised that instead of returning LRESULT(1) I should call the default window proc (as it is used in Win32 C++ programs), but this still didn't solve the problem, the frame was painted but the buttons weren't working, although I was able to update labels... So I had to abandon this solution too.
After searching some more on the internet I've found a great article here (edit: link is dead, original article can be found here), where a static hidden window is created to handle windows messages. I managed to code it for my application and it works great. (I had to further extend the classes from JNA because several functions were not included. I can post my code if someone is interested.)
Hope this helps.
Related
i have a class(location2.java) that finds location for me,I use this code in my class :
What is the simplest and most robust way to get the user's current location on Android?
and I have a service that override that abstract "locationResult";Now i want my service after running its codes,service doesn't finish and stay alive for receiving location from location2.java.
appreciating any help for this.
#Override
public int onStartCommand(Intent intent, int flags, int startId) {
Location2.LocationResult locate = new Location2.LocationResult() {
#Override
public void gotLocation(Location location1, Boolean Gps, Boolean Net) {
if (location1 != null) {
Log.e("Loc", String.valueOf(location1.getLatitude()));
}
try {
//this is a method that i want to be run after receiving location from location2.java
json_maker(location1, speed_computation(location1), Gps, Net);
} catch (JSONException e) {
e.printStackTrace();
}
}
};
Location2 location = new Location2();
location.getLocation(context, locate);
return Service.START_FLAG_REDELIVERY;
}
The most successful way is to use return START_STICKY.
"and if service wants to restart, multiple constants for example START_STICKY can be used.doesn't it?" - Yes, we can use.
START_STICKY
Constant to return from onStartCommand(Intent, int, int) if this service's process is killed while it is started (after returning from onStartCommand(Intent, int, int)), then leave it in the started state but don't retain this delivered intent. Developer guide: Android
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'm trying to create a web app which will check several service status, server stats etc. I found this http://www.jcraft.com/jsch/ seems to be pretty nice ssh java implementation. But every time I log in in to server I'm prompted to confirm RSA key fingerprint like this :
How can I override this, to always confirm yes without any prompts? I want to remove the whole swing part, I want to make this without any interaction, like this example code I took from the examples available on jscraft.com :
http://www.jcraft.com/jsch/examples/Exec.java
I'm not so familiar with swing and with java in general.
public class ManoUserInfo implements UserInfo {
String passwd;
public void setPassword(String pass) {
passwd = pass;
}
#Override
public String getPassphrase() {
return null;
}
public String getPassword() {
return passwd;
}
public boolean promptPassword(String arg0) {
return true;
}
public boolean promptPassphrase(String arg0) {
return true;
}
//this method responsible for that message, so just make it return true
public boolean promptYesNo(String arg0) {
// Object[] options = {"yes", "no"};
/* int foo = JOptionPane.showOptionDialog(null,
arg0,
"Warning",
JOptionPane.DEFAULT_OPTION,
JOptionPane.WARNING_MESSAGE,
null, options, options[0]);*/
return true;
}
public void showMessage(String message) {
JOptionPane.showMessageDialog(null, message);
}
You have to understand why this message pops up.
SSH is a secure service, meaning that the identity of the client and the identity of the server are guaranteed. To guarantee that you actually reached the server you want to reach (for how it is possible that you connect to the wrong server without your knowledge, google "DNS cache poisoning"), the client displays the recieved server name and fingerprint. These values identify the server. You are supposed to look if this is in fact the fingerprint you generated on the server by comparing the fingerprint through a secure channel (via telephone with the server admin, for instance).
Having said that, usual SSH clients save your decision to accept the fingerprint/server name and do not ask again. It seems that your client does not. So you either have the option to change the source code (if it's licensed under an open license) or find a way to automatically press "Yes" whenever this question pops up (this can be achieved with toolkits like Autoit 3 with a very short script).
check out http://sourceforge.net/projects/sshtools/
I am rewriting the existing C++ application and adapting it for Android environment.
In the code there is a PostMessage statement:
PostMessage( bExitApp ? WM_CLOSE : WM_LOGIN, wParam, lParam );
Does anyone know what is the most appropriate way to achieve tha same result in Android (Java)?
Is it well enough to create two methods like OnLogin() and OnClose() the following way:
private void OnLogin(long arg0, long arg1)
{
//some logic here
}
private void OnClose(long arg0, long arg1)
{
//some logic here
}
and then write
if(bExitApp)
(
OnLogin(arg0, arg1)
)
else
{
OnClose(arg0, arg1)
}
?
That may work. The difference is that postMessage runs after the event has been fully processed and you are back at the top of the event loop. You can simulate the behavior of PostMessage by using Handler.post(Runnable r) where you use the handler of the GUI thread.
I'm looking for a simple solution for a yes/no dialog to use in a Java ME midlet. I'd like to use it like this but other ways are okey.
if (YesNoDialog.ask("Are you sure?") == true) {
// yes was chosen
} else {
// no was chosen
}
You need an Alert:
An alert is a screen that shows data to the user and waits for a certain period of time before proceeding to the next Displayable. An alert can contain a text string and an image. The intended use of Alert is to inform the user about errors and other exceptional conditions.
With 2 commands ("Yes"/"No" in your case):
If there are two or more Commands present on the Alert, it is automatically turned into a modal Alert, and the timeout value is always FOREVER. The Alert remains on the display until a Command is invoked.
These are built-in classes supported in MIDP 1.0 and higher. Also your code snippet will never work. Such an API would need to block the calling thread awaiting for the user to select and answer. This goes exactly in the opposite direction of the UI interaction model of MIDP, which is based in callbacks and delegation. You need to provide your own class, implementing CommandListener, and prepare your code for asynchronous execution.
Here is an (untested!) example class based on Alert:
public class MyPrompter implements CommandListener {
private Alert yesNoAlert;
private Command softKey1;
private Command softKey2;
private boolean status;
public MyPrompter() {
yesNoAlert = new Alert("Attention");
yesNoAlert.setString("Are you sure?");
softKey1 = new Command("No", Command.BACK, 1);
softKey2 = new Command("Yes", Command.OK, 1);
yesNoAlert.addCommand(softKey1);
yesNoAlert.addCommand(softKey2);
yesNoAlert.setCommandListener(this);
status = false;
}
public Displayable getDisplayable() {
return yesNoAlert;
}
public boolean getStatus() {
return status;
}
public void commandAction(Command c, Displayable d) {
status = c.getCommandType() == Command.OK;
// maybe do other stuff here. remember this is asynchronous
}
};
To use it (again, untested and on top of my head):
MyPrompter prompt = new MyPrompter();
Display.getDisplay(YOUR_MIDLET_INSTANCE).setCurrent(prompt.getDisplayable());
This code will make the prompt the current displayed form in your app, but it won't block your thread like in the example you posted. You need to continue running and wait for a commandAction invocation.
I dont have programed in Java ME, but i found in it's reference for optional packages the
Advanced Graphics and User Interface API, and it's used like the Java SE API to create these dialogs with the JOptionPane Class
int JOptionPane.showConfirmDialog(java.awt.Component parentComponent, java.lang.Object >message, java.lang.String title, int optionType)
Return could be
JOptionPane.YES_OPTION, JOptionPane.NO_OPTION, JOptionPane.CANCEL_OPTION...