what i am trying to do is that on click of a button in screen1, i try push the screen2 repeatedly with different images and different Transition Context.
the code is as follows
public void fieldChanged(Field field, int context)
{
if(field==slideButton)
{
for(int i=0;i<bitmaps.length;i++)
{
slideScreen = new SliderScreen(bitmaps[i]);
UiApplication.getUiApplication().pushScreen(slideScreen);
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
UiApplication.getUiApplication().popScreen(slideScreen);
}
}
}
}
Problem is that nothing appears.Is there any other way to achieve this..
Fixed version of your initial idea:
public void fieldChanged(Field field, int context) {
if (field==slideButton) {
final UiApplication app = UiApplication.getUiApplication();
new Thread(new Runnable() {
public void run() {
for (int i = 0; i < bitmaps.length; i++) {
final SliderScreen slideScreen =
new SliderScreen(bitmaps[i]);
app.invokeAndWait(new Runnable() {
public void run() {
app.pushScreen(slideScreen);
}
});
try {
Thread.sleep(2000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
app.invokeAndWait(new Runnable() {
public void run() {
app.popScreen(slideScreen);
}
});
}
}
}).start();
}
}
Your code did not work because the UI thread was sleeping between push and pop, so it has no time/chance to start drawing the screen. Note I moved the entire action into a separate thread. So now the main UI thread has free time to actually make drawing.
Related
I have the following class which has multiple custom ThreadPoolTaskExecutors I am showing it with one in this example.
#Configuration
#EnableAsync
public class ExecutorConfig {
#Bean(name = "streetCheckerExecutor")
public Executor getStreetAsyncExecutor() {
ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
executor.setCorePoolSize(50);
executor.setQueueCapacity(1000000);
executor.setThreadNamePrefix("streetCheckerExecutor-");
executor.initialize();
return executor;
}
}
I have the following class which gets content from the database, I want to be able to check the queue size of streetCheckerExecutor and if it's less than a certain number, to add the content to the queue
#Component
public class StreetChecker {
#Autowired
StreetRepository streetRepository;
#Autowired
StreetCheckService streetChecker;
#EventListener(ApplicationReadyEvent.class)
public void checkStreets() {
try {
List<Street> streetList = streetRepository.getStreets();
for (int i = 0; i < streetList.size(); i++) {
streetChecker.run(streetList.get(i));
}
} catch (Exception e) {
e.printStackTrace();
} finally {
System.out.println("---------------------");
}
}
}
And below is the worker class
#Component
public class StreetCheckService {
#Async("streetCheckerExecutor")
public void run(Content content) {
try {
//do work
} catch (Exception e) {
e.printStackTrace();
} finally {
}
}
}
I am working with a lot of data and I don't want to grab everything from the database every time, but I want to check the queue size of streetCheckerExecutor and if it's less than a number, I want to get more content from the database and add it to the streetCheckerExecutor queque
Below is how I'm thinking I can do it by converting the above checkStreets to the one below
#EventListener(ApplicationReadyEvent.class)
public void checkStreets() {
while (true) {
try {
// check the queue size of streetCheckerExecutor
// if less than a number
// add to the queue
// else keep waiting and will try again in X minutes
} catch (Exception e) {
} finally {
try {
Thread.sleep(1000 * 60);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
But how would I be able to get the size of the queue in the checkStreets() method?
You can just autowire in your ThreadPoolTaskExecutor and get the queue with getThreadPoolExecutor().getQueue().
#Autowire
#Qualifier("streetCheckerExecutor")
private Executor streetExecutor;
#EventListener(ApplicationReadyEvent.class)
public void checkStreets() {
while (true) {
try {
final BlockingQueue<Runnable> queue = streetExecutor.getThreadPoolExecutor().getQueue();
if(queue.size() <= 5) {
queue.add(() -> {
final List<Street> streetList = streetRepository.getStreets();
streetList.forEach(street -> {
streetChecker.run(street);
});
});
}
} catch (Exception e) {
} finally {
try {
Thread.sleep(1000 * 60);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
i'm not sure this is what you meant, but something like this maybe.
For a few days I have been trying to create a JPanel, that comes flying in from the side. I found the Universal Tween Engine and also saw a few demos but for some reason I was never able to make it work in my own code. For the sake of simplicity let's just attempt to move a JPanel (containing an image in a JLabel) from (0,0) to (600,0) on a JFrame. This is what I've got so far and the closest I have ever gotten to actually moving things with this framework, all it does it make the JPanel jump to its destination within the first tick or so. It is supposed to be so simple but I must be missing something...
SlideTest.java - Creating the UI, initializing the Thread + Tween
public class SlideTest {
TweeningPane p;
public TweenManager tweenManager;
public static void main(String[] args) {
new SlideTest();
}
public SlideTest() {
try {
setupGUI();
} catch (IOException e) {
e.printStackTrace();
}
tweenManager = new TweenManager();
AnimationThread aniThread = new AnimationThread();
aniThread.setManager(tweenManager);
aniThread.start();
Tween.to(p, 1, 10.0f).target(600).ease(Quad.OUT).start(tweenManager);
}
public void setupGUI() throws IOException {
JFrame f = new JFrame();
f.setSize(800, 600);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
p = new TweeningPane();
JLabel l = new JLabel(new ImageIcon("E:/Pictures/Stream/aK6IX4V.png"));
f.setLayout(null);
p.add(l);
p.setBounds(0, 0, 300, 300);
f.add(p);
f.setVisible(true);
}
}
AnimationThread.java - The Thread, that is supposed to keep my TweenManager updated as much/often as possible
public class AnimationThread extends Thread {
TweenManager tm;
public void setManager(TweenManager tweenmanager) {
this.tm = tweenmanager;
}
public void run() {
while (true) {
//System.out.println("MyThread running");
tm.update(MAX_PRIORITY);
try {
sleep(40);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
TweeningPane.java - My Object(JPanel), I want to move across the JPanel
public class TweeningPane extends JPanel implements TweenAccessor<JPanel> {
private static final long serialVersionUID = 1L;
#Override
public int getValues(JPanel arg0, int arg1, float[] arg2) {
return (int) arg0.getBounds().getX();
}
#Override
public void setValues(JPanel arg0, int arg1, float[] arg2) {
arg0.setBounds((int) arg2[0], 0, 300, 300);
}
}
I have finally figured it out. I was simply using the framework in a wrong way as I expected. I'm not sure whether all these steps were needed but this is what I went through in order to make it work: (for future reference)
I had to register my accessor to the engine:
Tween.registerAccessor(TweeningPane.class, new TweeningPane());
And the thread itself now looks like this; I had to give the manager's update method the elapsed time as a parameter.
public void run() {
long ms1 = System.currentTimeMillis();
while (true) {
//System.out.println("MyThread running");
tm.update((System.currentTimeMillis() - ms1) / 1000f);
try {
Thread.sleep(40);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
I have implemented simple RxEventBus which starts emitting events, even if there is no subscribers. I want to cache last emitted event, so that if first/next subscriber subscribes, it receive only one (last) item.
I created test class which describes my problem:
public class RxBus {
ApplicationsRxEventBus applicationsRxEventBus;
public RxBus() {
applicationsRxEventBus = new ApplicationsRxEventBus();
}
public static void main(String[] args) {
RxBus rxBus = new RxBus();
rxBus.start();
}
private void start() {
ExecutorService executorService = Executors.newScheduledThreadPool(2);
Runnable runnable0 = () -> {
while (true) {
long currentTime = System.currentTimeMillis();
System.out.println("emiting: " + currentTime);
applicationsRxEventBus.emit(new ApplicationsEvent(currentTime));
try {
Thread.sleep(500);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
};
Runnable runnable1 = () -> applicationsRxEventBus
.getBus()
.subscribe(new Subscriber<ApplicationsEvent>() {
#Override
public void onCompleted() {
}
#Override
public void onError(Throwable throwable) {
}
#Override
public void onNext(ApplicationsEvent applicationsEvent) {
System.out.println("runnable 1: " + applicationsEvent.number);
}
});
Runnable runnable2 = () -> applicationsRxEventBus
.getBus()
.subscribe(new Subscriber<ApplicationsEvent>() {
#Override
public void onCompleted() {
}
#Override
public void onError(Throwable throwable) {
}
#Override
public void onNext(ApplicationsEvent applicationsEvent) {
System.out.println("runnable 2: " + applicationsEvent.number);
}
});
executorService.execute(runnable0);
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
executorService.execute(runnable1);
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
executorService.execute(runnable2);
}
private class ApplicationsRxEventBus {
private final Subject<ApplicationsEvent, ApplicationsEvent> mRxBus;
private final Observable<ApplicationsEvent> mBusObservable;
public ApplicationsRxEventBus() {
mRxBus = new SerializedSubject<>(BehaviorSubject.<ApplicationsEvent>create());
mBusObservable = mRxBus.cache();
}
public void emit(ApplicationsEvent event) {
mRxBus.onNext(event);
}
public Observable<ApplicationsEvent> getBus() {
return mBusObservable;
}
}
private class ApplicationsEvent {
long number;
public ApplicationsEvent(long number) {
this.number = number;
}
}
}
runnable0 is emitting events even if there is no subscribers. runnable1 subscribes after 3 sec, and receives last item (and this is ok). But runnable2 subscribes after 3 sec after runnable1, and receives all items, which runnable1 received. I only need last item to be received for runnable2. I have tried cache events in RxBus:
private class ApplicationsRxEventBus {
private final Subject<ApplicationsEvent, ApplicationsEvent> mRxBus;
private final Observable<ApplicationsEvent> mBusObservable;
private ApplicationsEvent event;
public ApplicationsRxEventBus() {
mRxBus = new SerializedSubject<>(BehaviorSubject.<ApplicationsEvent>create());
mBusObservable = mRxBus;
}
public void emit(ApplicationsEvent event) {
this.event = event;
mRxBus.onNext(event);
}
public Observable<ApplicationsEvent> getBus() {
return mBusObservable.doOnSubscribe(() -> emit(event));
}
}
But problem is, that when runnable2 subscribes, runnable1 receives event twice:
emiting: 1447183225122
runnable 1: 1447183225122
runnable 1: 1447183225122
runnable 2: 1447183225122
emiting: 1447183225627
runnable 1: 1447183225627
runnable 2: 1447183225627
I am sure, that there is RxJava operator for this. How to achieve this?
Your ApplicationsRxEventBus does extra work by reemitting a stored event whenever one Subscribes in addition to all the cached events.
You only need a single BehaviorSubject + toSerialized as it will hold onto the very last event and re-emit it to Subscribers by itself.
You are using the wrong interface. When you susbscribe to a cold Observable you get all of its events. You need to turn it into hot Observable first. This is done by creating a ConnectableObservable from your Observable using its publish method. Your Observers then call connect to start receiving events.
You can also read more about in the Hot and Cold observables section of the tutorial.
I'm having issues trying to understand how AsyncTask().get() actually works. I know it's a synchronous execution, However: I don't know how execute() and get() are connected.
I have this sample code from Google's docs:
// Async Task Class
class DownloadMusicfromInternet extends AsyncTask<String, String, String> {
// Show Progress bar before downloading Music
#Override
protected void onPreExecute() {
super.onPreExecute();
Log.d("Task: ", "onPreExecute()");
}
// Download Music File from Internet
#Override
protected String doInBackground(String... f_url) {
for (int i = 0; i < 100; i++){
try {
Thread.sleep(100);
Log.d("Task: ", String.valueOf(i));
} catch (InterruptedException e) {
e.printStackTrace();
}
}
return null;
}
// While Downloading Music File
protected void onProgressUpdate(String... progress) {
// Set progress percentage
Log.d("Task: ", "onProgressUpdate()");
}
// Once Music File is downloaded
#Override
protected void onPostExecute(String file_url) {
Log.d("Task: ", "onPostExecute()");
}
}
Now, from a button.onClick() I call this in 3 ways:
new DownloadMusicfromInternet().execute("");//works as expected, the "normal" way
//works the normal way, but it's synchronous
try {
new DownloadMusicfromInternet().execute("").get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
//does not work
try {
new DownloadMusicfromInternet().get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
I'm confused as to how exactly execute() triggers doInBackground() and then immediately returns if get() is called, while get() has no effect on doInBackground() whatsoever.
execute() schedules the internal FutureTask (usually on a internal Executor) and returns immediately.
get() just calls FutureTask.get() on this internal future, i.e. it waits (if necessary) for the result.
So calling get() without calling execute() first waits indefinitely, as the result will never be available.
As you mentioned, when used the normal way, get() is not needed at all, as the result is handled in onPostExecute(). I didn't even know it existed before I tried to understand your question
I'm developing an android app that requires to make UI changes according to a background thread processing results, I tried the following code at first:
Thread run_time = new Thread (){
public void run(){
ConnectToServer connect = new ConnectToServer(null);
while(true){
String server_response = connect.getServerResponse();
if(!server_response.equals(null)){
setResponse(server_response);
response_received();
}
}
}
};
run_time.start();
but my App crashes because i tried to make a UI changes from that background thread, then I tried that way:
runOnUiThread(new Runnable() {
public void run(){
ConnectToServer connect = new ConnectToServer(null);
while(true){
String server_response = connect.getServerResponse();
if(!server_response.equals(null)){
setResponse(server_response);
response_received();
}
}
}
});
but i got that exception:
01-29 16:42:17.045: ERROR/AndroidRuntime(605): android.os.NetworkOnMainThreadException
01-29 16:42:17.045: ERROR/AndroidRuntime(605): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1084)
01-29 16:42:17.045: ERROR/AndroidRuntime(605): at libcore.io.BlockGuardOs.recvfrom(BlockGuardOs.java:151)
01-29 16:42:17.045: ERROR/AndroidRuntime(605): at libcore.io.IoBridge.recvfrom(IoBridge.java:503)
01-29 16:42:17.045: ERROR/AndroidRuntime(605): at java.net.PlainSocketImpl.read(PlainSocketImpl.java:488)
01-29 16:42:17.045: ERROR/AndroidRuntime(605): at java.net.PlainSocketImpl.access$000(PlainSocketImpl.java:46)
and after search i found that I must run the code as AsyncTask to avoid these problems, but when attempting to use it i found that it's must be used with small tasks only not like a thread that runs in the background all the run_time.
So, what's the best day to run a thread or a task in the background in whole the run_time and also reflect it's changes to the UI.
EDIT:
For Long running network work you have a few options.
First and formost check the android docs on this topic:
http://developer.android.com/training/basics/network-ops/index.html
Next, I generally use Services for this type of thing:
https://developer.android.com/guide/components/services.html
I will point you at the vogella tutorial for this as well:
http://www.vogella.com/tutorials/AndroidServices/article.html
For communication from threads/asynctasks/services to the UI use Handlers:
Use Handlers:
static public class MyThread extends Thread {
#Override
public void run() {
try {
// Simulate a slow network
try {
new Thread().sleep(5000);
} catch (InterruptedException e) {
e.printStackTrace();
}
downloadBitmap = downloadBitmap("http://www.devoxx.com/download/attachments/4751369/DV11");
// Updates the user interface
handler.sendEmptyMessage(0);
} catch (IOException e) {
e.printStackTrace();
} finally {
}
}
}
handler = new Handler() {
#Override
public void handleMessage(Message msg) {
// cal uiMethods here...
imageView.setImageBitmap(downloadBitmap);
// dialog.dismiss();
}
};
Taken from this tutorial:
http://www.vogella.com/tutorials/AndroidBackgroundProcessing/article.html
You can make this more interesting by defining constant_codes which corespond to the desired action:
private int DO_THIS = 0x0;
private int DO_THAT = 0x1;
// in your UI:
public void handleMessage(Message msg) {
// cal uiMethods here...
switch(msg.what()){
case(DO_THIS):
// do stuff
break;
case(DO_THAT):
// do other stuff
break;
}
}
// in your thread:
Message m = handler.obtainMessage(DO_THIS);
handler.sendMessage(m);
If the thread code (asynch task, service etc...) is separate from the UI you can use Broadcasts to pass the data between the two and then use Handlers from there to act on the UI thread.
you need to use handlers
here is documntation: https://developer.android.com/training/multiple-threads/communicate-ui.html
Use this code - it may contain compile time error you have to do it correct
public class MainActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Connect connect = new Connect();
connect.execute();
}
class Connect extends AsyncTask<Void, String, Void>
{
#Override
protected Void doInBackground(Void... params)
{
ConnectToServer connect = new ConnectToServer(null);
while(true)
{
String server_response = connect.getServerResponse();
if(!server_response.equals(null))
{
publishProgress(server_response);
//setResponse(server_response);
response_received();
}
}
return null;
}
#Override
protected void onProgressUpdate(String... values) {
super.onProgressUpdate(values);
setResponse(values[0]);
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
}
}
}
You need "handlers" along with "loopers" for optimization
Example:
public void myMethod(){
Thread background = new Thread(new Runnable(){
#Override
public void run(){
Looper.prepare();
//Do your server process here
Runnable r=new Runnable() {
#Override
public void run() {
//update your UI from here
}
};
handler.post(r);
Looper.loop();
}
});
background.start();
}
And of course this is without using AsyncTask