I've got an ImageButton which is declared in my layout xml. I've told it when it is clicked, to call a certain method, playSound.
Inside of playSound, the phone plays a sound which lasts for a certain amount of time, 5277 ms to be precise. I want playSound to be able to change the ImageResource of the ImageButton for a certain amount of time (5400 ms), and then change it back.
Here's my code:
ImageButton dBellButt;
public void onCreate(Bundle bundle) {
super.onCreate(bundle);
setContentView(R.layout.activity_main);
dBellButt.setImageResource(R.drawable.doorbell2);
public void playSound(View view) {
dBellButt.setImageResource(R.drawable.doorbell);
dBell.start();
if (vibeOn) {
Vibrator vibe = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
vibe.vibrate(500);
} else {
// No vibration
}
try {
Thread.sleep(5400);
} catch (InterruptedException e) {
}
dBellButt.setImageResource(R.drawable.doorbell2);
}
doorbell2 is an image of a lit doorbell. doorbell is an image of an unlit doorbell.
I can switch the position of the two images and it'll work just fine, ie: if I have the doorbell created lit, when the button is pressed, it'll stay lit until 5400 ms, after which the image changes. If I create the application with the doorbell 'lit,' I cannot change it at all.
Hopefully that made sense.
In short, I cannot get the ImageButton to change ImageResource. The setImageResource after the Thread.sleep(); works fine, but the one before it does not.
How come this isn't working?
Thanks!
Nathan
EDIT:
Figured I would attach my xml just in case.
<ImageButton
android:id="#+id/dBellButton"
android:layout_height="fill_parent"
android:layout_width="fill_parent"
android:scaleType="fitCenter"
android:padding="0dp"
android:background="#null"
android:onClick="playSound"
android:contentDescription="#string/ImgDesc" />
Cheers
I found a solution. I ended up using the timer class.
Here's my code:
public void playSound(View view) {
dBell.start();
if (vibeOn) {
Vibrator vibe = (Vibrator) getSystemService(Context.VIBRATOR_SERVICE);
vibe.vibrate(500);
} else {
// No vibration
}
Timer timer = new Timer();
TimerTask picSwitch1 = new TimerTask() {
public void run() {
handler.post(new Runnable() {
public void run() {
dBellButt.setImageResource(R.drawable.doorbell);
}
});
}
};
TimerTask picSwitch2 = new TimerTask() {
public void run() {
handler.post(new Runnable() {
public void run() {
dBellButt.setImageResource(R.drawable.doorbell2);
}
});
}
};
timer.schedule(picSwitch1, 10);
timer.schedule(picSwitch2, 5400);
}
Using this allows the picture to switch after the delayed time.
The problem I was having with the sleep function was it would cause the application to freeze up (duh...). I couldn't use any of the other given interface. This solution fixes that problem. I'll attach the links I used to solve this.
http://developer.android.com/reference/java/util/Timer.html
http://blog.redkitmedia.com/timer-android-example/
Android timer/timertask causing my app to crash?
Related
I have a test project with Room database. Using Asynctask I can successfully insert an object with some test data into the database. I'm trying to learn RxJava and replace Asynctask with RxJava's observer, but it doesn't work. I have read alot of documentation and watched tutorials, but I don't think I quite get it. Here's the relevant code:
Here I set my Room object with the data from my List:
for(ObjectForArray item: listToDatabase) {
myRoomEntity.setName( item.getName() );
Log.d( "TAG", myRoomEntity.getName() );
}
Then I try to use RxJava Observable to insert data into the database. This was originally and successfully done using Asynctask:
Observable<MyRoomEntity> myRX = Observable
.just(myRoomEntity)
.subscribeOn( Schedulers.io() )
.observeOn( AndroidSchedulers.mainThread() );
myRX.subscribe( new Observer<MyRoomEntity>() {
#Override
public void onSubscribe(Disposable d) {
Log.d("TAG ONSUBSCRIBE", d.toString());
try {
myViewModel.insertDatabase( myRoomEntity );
Log.d( "TAG", "Populating database Success" );
}catch(Error error) {
Log.d( "TAG", error.toString() );
}
}
The OnNext, OnError and OnComplete are empty.
When I run the project it crashes with the error:
Cannot access database on the main thread since it may potentially lock the UI for a long period of time.
I'm obviously using RxJava wrong since the point is to do asynchronous tasks away from the main thread.
i have use RX java in replace of Asyntask as it has been deprecated in android 9
there are multiple replacements that android provides like Executors, threads, Listenable Futures , Coroutines 🔥, so you are looking how to implement this with rxjava and how RX Java java helps your to migrate just add these dependencies first in gradle
implementation "io.reactivex.rxjava2:rxjava:2.2.20"
implementation "io.reactivex.rxjava2:rxandroid:2.1.1"
once you import lets start working with RX java i will let you know where you can put background task, pre execute, on post execute like asynctask
lets start codding with Rx java first , i have comment in the method that will help you to put the code
Observable.fromCallable(new Callable<Boolean>() {
#Override
public Boolean call() throws Exception {
/// here is your background task
return true;
}
}).subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread())
.subscribe(new Observer<Boolean>() {
#Override
public void onSubscribe(Disposable d) {
//// pre execute here is my progress dialog
showProgressDialog(getString(R.string.scanning));
}
#Override
public void onNext(Boolean aBoolean) {
//// here is on sucess you can do anystuff here like
if (aBoolean){
/// if its value true you can go ahead with this
}
}
#Override
public void onError(Throwable e) {
/// this helps you to go if there is any error show dialog whatever you wants here
Log.e("error of kind",e.getMessage() );
}
#Override
public void onComplete() {
/// when your task done means post execute
}
});
once its done lets start working with implementation
Observable.fromCallable(new Callable<Boolean>() {
#Override
public Boolean call() throws Exception {
/// here is your background task
uribitmap = getScannedBitmap(original, points);
uri = Utils.getUri(getActivity(), uribitmap);
scanner.onScanFinish(uri);
return true;
}
}).subscribeOn(Schedulers.io()).observeOn(AndroidSchedulers.mainThread())
.subscribe(new Observer<Boolean>() {
#Override
public void onSubscribe(Disposable d) {
//// pre execute here is my progress dialog
showProgressDialog(getString(R.string.scanning));
}
#Override
public void onNext(Boolean aBoolean) {
//// here is on sucess you can do anystuff here like
if (aBoolean){
/// if its value true you can go ahead with this
}
}
#Override
public void onError(Throwable e) {
/// this helps you to go if there is any error show dialog whatever you wants here
Log.e("error of kind",e.getMessage() );
}
#Override
public void onComplete() {
/// when your task done means post execute
uribitmap.recycle();
dismissDialog();
}
});
now i will do this with executors :
/// pre execute you can trigger to progress dialog
showProgressDialog(getString(R.string.scanning));
ExecutorService executors = Executors.newSingleThreadExecutor();
executors.execute(new Runnable() {
#Override
public void run() {
//// do background heavy task here
final Bitmap uribitmap = getScannedBitmap(original, points);
uri = Utils.getUri(getActivity(), uribitmap);
scanner.onScanFinish(uri);
new Handler(Looper.getMainLooper()).post(new Runnable() {
#Override
public void run() {
//// Ui thread work like
uribitmap.recycle();
dismissDialog();
}
});
}
});
You are getting this error because you are trying to insert an Object on the main (UI) thread.
You should do something like this:
Observable.fromCallable(() -> myViewModel.insertDatabase( myRoomEntity ))
.subscribeOn( Schedulers.io() )
.observeOn( AndroidSchedulers.mainThread() );
And then use an Observer to subscribe to the Observable.
Please try restructuring your code like this:
Completable.fromAction(() -> myViewModel.insertDatabase(myRoomEntity))
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(() -> Log.d("TAG", "Populating database Success"),
throwable -> Log.d("TAG", throwable.toString()))
Considerations:
If your myRoomEntity is not available before this whole construct gets subscribed, make sure you use defer http://reactivex.io/documentation/operators/defer.html
Your subscribe section handlers are operating on "main", that's why you were receiving a crash.
If possible, avoid unnecessary just calls
Warning: This is my first time using threads and my first time trying out an animation. Please bear with me.
I want to rotate an ImageView. I set up a thread for it:
public class ThreadAnimation extends Thread
{
private ImageView iv;
private RotateTransition rt;
public ThreadAnimation(ImageView iv)
{
this.iv = iv;
}
#Override
public void run()
{
while (true)
{
RotateTransition r = new RotateTransition();
r.setToAngle(360);
r.setCycleCount(1);
r.setDuration(Duration.millis(300));
r.setNode(iv);
r.play();
try
{
sleep(100);
} catch (InterruptedException e)
{
return;
}
}
}
}
I call this inside my controller class, upon pressing a Button.
animation.setOnAction(new EventHandler<ActionEvent>()
{
#Override
public void handle (ActionEvent abschicken)
{
ThreadAnimation thread = null; //ANIMATION PIZZA
if (thread == null)
{
thread = new ThreadAnimation(olivenview);
thread.start();
}
}
});
My ImageView olivenview will rotate just like I wanted it to. However it takes quite a long time until it seems to stop (I can see it because the button triggering it still looks triggered for a while) and when I go ahead to press it a second time afterwards, I get a nonstop error stream with a lot of null pointer exceptions. I am very clueless, can anyone help me out? Is this due to my Thread Setup or does the problem lie somewhere else (in code that I didn't post here)?
I believe you do not need threads for this. Notice the .play() method returns immediately and the animation will run in the background.
That being said, try this.
...
//Create your rotation
final RotateTransition r = new RotateTransition();
r.setToAngle(360);
r.setCycleCount(1);
r.setDuration(Duration.millis(300));
r.setNode(iv);
//When the button is pressed play the rotation. Try experimenting with .playFromStart() instead of .play()
button.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent action) {
r.play();
}
});
...
On an other note I recommend switching to java 8 so that you can use lambda expressions instead of the anonymous class!
I have a project with 2 activities, the first one is the "SplashActivity" - where I load some network data - the second one, the MainActivity.
Inside of my MainActivity I have a fragment and inside of this fragment a webview. My first point is, when the user clicks on back button, the SplashScreen is open again.
The back button should behave like:
When the user doesn't navigate inside of my webview, close the app.
When the user navigates in webview, use the back history of the browswer.
I read about back stack here: http://developer.android.com/training/implementing-navigation/temporal.html#back-webviews
I didn't understand at all how it should work, because I have all cases "mixed". Anyone knows what should I do to fix this problem?
Any idea or sample code will be appreciate!
Define Webview wb as a global variable. Then try this;
#Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if(event.getAction() == KeyEvent.ACTION_DOWN){
switch(keyCode)
{
case KeyEvent.KEYCODE_BACK:
if(wb.canGoBack() == true){
wb.goBack();
}else{
new AlertDialog.Builder(this).setIcon(android.R.drawable.ic_dialog_alert).setTitle("Application will be closed")
.setMessage("Close app?")
.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
finish();
System.exit(0);
}
}).setNegativeButton("No", null).show();
}
return true;
}
}
return super.onKeyDown(keyCode, event);
}
}
I'm trying to add a click event listener to the label of all column-headers of a TableView, as follows:
for (final Node header : tblView.lookupAll(".column-header > .label")) {
if ((header != null) && (header instanceof Label)) {
final Label headerLabel = (Label) header;
// ...
}
}
Now, the problem is that if I do this in the initialize()-function of the Controller, the Scenegraph is not yet rendered and the above code won't work. Hence my question: Is there some kind of a post-render event?
many thanks in advance.
There is a WINDOW_SHOWN event in javafx.stage.WindowEvents. That is not (imo) "Post render event" but you can utilize it in similar manner, by adding an event handler to the Stage (which extends from Window).
In the initialize method of controller class, get the primary stage and then:
stage.addEventHandler(WindowEvent.WINDOW_SHOWN, new EventHandler<WindowEvent>() {
#Override
public void handle(WindowEvent window) {
Platform.runLater(new Runnable() {
#Override
public void run() {
addListenerToColumnHeaders();
}
});
}
});
Hope this helps, since didn't try myself.
so i'm trying to set up an application where i have multiple panels inside a jframe. lets say 3 of them are purely for display purposes, and one of them is for control purposes. i'm using a borderLayout but i don't think the layout should really affect things here.
my problem is this: i want the repainting of the three display panels to be under the control of buttons in the control panel, and i want them to all execute in sync whenever a button on the control panel is pressed. to do this, i set up this little method :
public void update(){
while(ButtonIsOn){
a.repaint();
b.repaint()
c.repaint();
System.out.println("a,b, and c should have repainted");
}
}
where a,b, and c are all display panels and i want a,b,and c to all repaint continously until i press the button again. the problem is, when i execute the loop, the message prints in an infinite loop, but none of the panels do anything, ie, none of them repaint.
i've been reading up on the event dispatch thread and swing multithreading, but nothing i've found so far has really solved my problem. could someone give me the gist of what i'm doing wrong here, or even better, some sample code that handles the situation i'm describing? thanks...
The java.util.concurrent package provides very powerful tools for concurrent programing.
In the code below, I make use of a ReentrantLock (which works much like the Java synchronized keyword, ensuring mutually exclusive access by multiple threads to a single block of code). The other great thing which ReentrantLock provides are Conditions, which allow Threads to wait for a particular event before continuing.
Here, RepaintManager simply loops, calling repaint() on the JPanel. However, when toggleRepaintMode() is called, it blocks, waiting on the modeChanged Condition until toggleRepaintMode() is called again.
You should be able to run the following code right out of the box. Pressing the JButton toggle repainting of the JPanel (which you can see working by the System.out.println statements).
In general, I'd highly recommend getting familiar with the capabilities that java.util.concurrent offers. There's lots of very powerful stuff there. There's a good tutorial at http://docs.oracle.com/javase/tutorial/essential/concurrency/
import java.awt.Component;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Collection;
import java.util.Collections;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class RepaintTest {
public static void main(String[] args) {
JFrame frame = new JFrame();
JPanel panel = new JPanel()
{
#Override
public void paintComponent( Graphics g )
{
super.paintComponent( g );
// print something when the JPanel repaints
// so that we know things are working
System.out.println( "repainting" );
}
};
frame.add( panel );
final JButton button = new JButton("Button");
panel.add(button);
// create and start an instance of our custom
// RepaintThread, defined below
final RepaintThread thread = new RepaintThread( Collections.singletonList( panel ) );
thread.start();
// add an ActionListener to the JButton
// which turns on and off the RepaintThread
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
thread.toggleRepaintMode();
}
});
frame.setSize( 300, 300 );
frame.setVisible( true );
}
public static class RepaintThread extends Thread
{
ReentrantLock lock;
Condition modeChanged;
boolean repaintMode;
Collection<? extends Component> list;
public RepaintThread( Collection<? extends Component> list )
{
this.lock = new ReentrantLock( );
this.modeChanged = this.lock.newCondition();
this.repaintMode = false;
this.list = list;
}
#Override
public void run( )
{
while( true )
{
lock.lock();
try
{
// if repaintMode is false, wait until
// Condition.signal( ) is called
while ( !repaintMode )
try { modeChanged.await(); } catch (InterruptedException e) { }
}
finally
{
lock.unlock();
}
// call repaint on all the Components
// we're not on the event dispatch thread, but
// repaint() is safe to call from any thread
for ( Component c : list ) c.repaint();
// wait a bit
try { Thread.sleep( 50 ); } catch (InterruptedException e) { }
}
}
public void toggleRepaintMode( )
{
lock.lock();
try
{
// update the repaint mode and notify anyone
// awaiting on the Condition that repaintMode has changed
this.repaintMode = !this.repaintMode;
this.modeChanged.signalAll();
}
finally
{
lock.unlock();
}
}
}
}
jComponent.getTopLevelAncestor().repaint();
You could use SwingWorker for this. SwingWorker was designed to perform long running tasks in the background without blocking the event dispatcher thread. So, you need to extend SwingWorker and implement certain methods that will make sense to you. Note that all long running action should happen in the doInBackground() method, and the Swing UI elements should be updated only on the done() method.
So here is an example :
class JPanelTask extends SwingWorker<String, Object>{
JPanel panel = null;
Color bg = null;
public JPanelTask(JPanel panel){
this.panel = panel;
}
#Override
protected String doInBackground() throws Exception {
//loooong running computation.
return "COMPLETE";
}
#Override
protected void done() {
panel.repaint();
}
}
Now, in your "control" button's action performed event, you could do the following :
controlButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent arg0) {
JPanelTask task1 = new JPanelTask(panel1);
task1.execute();
JPanelTask task2 = new JPanelTask(panel2);
task2.execute();
//so on..
}
});
Another way is using javax.swing.Timer. Timer helps you to fire a change to your ui elements in a timely fasthion.This may not be the most appropriate solution. But it gets the work done too.
Again you should be careful about updating UI elements in right places.