I recently began working with Java and am exploring Android development. I was trying to port over one of the Java programs I made, but I am having some difficulty with getting the java Timer to function the same way in Android. I read through a number of posts and they, for the most part, indicated that it would be better to use the Handler class in android as opposed to Timer.
This was my timer in Java:
playTimer = new Timer(1000/model.getFPS(), new ActionListener() {
public void actionPerformed(ActionEvent evt) {
// do something
...
if( finished everything ) playTimer.stop();
}
});
And once a certain button was clicked, I would simply run "playTimer.start()" to start it.
As you can see, I had it set up so that the user could set the FPS they wanted (by simply setting the first parameter of the Timer class to 1000/model.getFPS()).
Now I've tried to do something similar in Android using handlers, but I am having some difficulty. It appears that the Handler ticks are not firing at the proper intervals. It seems that they are quite slow compared to what I need it to be. This is what I did in android so far:
public void startTimer() {
playHandler = new Handler();
startTime = System.currentTimeMillis();
playHandler.removeCallbacks(updateTimeTask);
playHandler.postDelayed(updateTimeTask, 0);
}
private Runnable updateTimeTask = new Runnable() {
public void run() {
// do something
...
if( finished everything ) playHander.cancel();
else {
playHandler.postDelayed(updateTimeTask, 1000/model.getFPS());
}
}
};
Excuse the semi-pseudocode. Can anyone shed any light? Thanks guys.
You can use a timer as below. The timer runs every second incrementing the counter. Displs the counter value in textview.
Timer runs on a different thread. SO you should set the text on the UI Thread.
The counter runs from 0 to 99. After 99 the timer is cancelled. Also cancel the timer when not required like in onPause().
public class MainActivity extends Activity {
TextView _tv,tv2;
Timer _t;
int _count=0;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
_tv = (TextView) findViewById( R.id.textView1 );
_t = new Timer();
_tv.setText(R.string.app_name);
_t.scheduleAtFixedRate( new TimerTask() {
#Override
public void run() {
_count++;
runOnUiThread(new Runnable() //run on ui thread
{
public void run()
{
_tv.setText(""+_count);
if(_count==99)
{
_t.cancel();
}
}
});
}
}, 1000, 1000 ); //change this value of 1000 to whatever you need.
}
#Override
protected void onPause() {
// TODO Auto-generated method stub
super.onPause();
_t.cancel();
}
}
If you decide not to use Timer (for whatever reason) you can just write a separate Thread that sleeps for x milliseconds and then wakes up and calls whatever Runnable you want it to call. That's going to be pretty precise. I have it working at the 10 millisecond level and it works quite nicely.
Just remember that it HAS to call a Runnable because a separate Thread can't have direct effect on anything on the main display thread.
public boolean keepPlayingAnimation = true
Handler h = new Handler()
Runnable updateDisplay = new Runnable(){
public void run(){
//do something in my display;
}
}
new Thread(){
public void run(){
while(keepPlayingAnimation){
try{
sleep(10);
}catch(Exception e){
}
h.post(updateDisplay);
}
}
}.start();
Just don't forget to set keepPlayingAnimation to false when you're done with this cause otherwise it will sit there running in the background for ever (or just about).
Take a look at Android Timer
It already has everything you need i guess. From ticking every 1 second to finish handly and so on.
Here is an example how to setup an TimerTask: setup
Not sure if you need such but i just remembered that i made this.
Related
I'm new to Android and I'm working on a tiny project with a set of strict parameters. One of them is to have a multifunction button that increments a timer every time it's clicked, and that starts only after I didn't increment said timer for 3 seconds.
I found three or four ways on how to set an alarm of sorts with Handler, CountDownTimer, Timer, or some other way, but I'm confused on how I can do what I'm looking for with just the onClick() method.
The function to wait for 3s(), I'm calling it after:
public void wait3s()
{
Thread thread = new Thread() {
#Override
public void run()
{
while (!isInterrupted()) {
try {
Thread.sleep(3000);
runOnUiThread(new Runnable() {
#Override
public void run() {
count++;
threeS.setText(String.valueOf(count));
}
});
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
};
thread.start();
}
My onClick() just calls these:
public void onClick(View view)
{
increment();
wait3s();
startStop();
}
As you can see, part of the issue is that I'm calling the wait3s() there at every click, and I need a way to control that Thread/Timer (whatever) without it creating a new one at every click. I'm being a little dumb now, but I have been on this for a while and I'm still coming out empty, since I never worked with this before.
Another option for the wait3s() function that I found would be like in this other StackOverflow thread.
Thank you
PS: Sorry for the title, I couldn't find a better way to describe it, if you have it, and have the power to change it, please do.
Handler.removeCallbacks will effectively cancel a runnable.
boolean timerStarted = false;
clockHandler = new Handler();
OnClick(){
if (!timerStarted){
incrementTimer();
clockHandler.removeCallbacks(null);
clockHandler.postDelayed(new Runnable() {
#Override
public void run() {
// maybe kick off another handler/runnable here to start your timer
timerStarted = true;
}
}
}, 3 * 60 * 1000);
} else {
startStop();
}
}
Here's how I solve it. Although the suggestions were closer, they weren't exactly spot on to what I was looking for, in terms of logic, they weren't exactly helpful, creating more issues. Perhaps it's due to my explanation of the problem, perhaps because I'm new to Android Studio and the explanations shared here with me. Pardon me if it looks like I'm just using my own answer for internet points, I just had to put a lot more to understand this by myself than what I actually got from the answers shared here.
public void wait3s()
{
t.schedule(new TimerTask() {
#Override
public void run() {
runOnUiThread(new Runnable() {
#Override
public void run() {
startStop();
}
});
}
}, 3000);
}
The variable t is a Timer(), and I had to import the classes java.util.Timer, and java.util.TimerTask. I called this method inside my increment() method and under onClick() I just have the increment() method. Turned out pretty neat.
I have developed an android application which extracts single line text messages from the server. Once a button is clicked, it makes a function call which gets the next message from the server. Some of those messages are time based,
i.e those messages have to be displayed in the TextView for a particular amount of time and after that time is elapsed, it should automatically make the function call to get the next message from the server(i.e without the button being clicked).
Could someone please help me out in achieving this.
I tried using while loop as follows:
while(!presentTime.equals(expiryTime)){
calculatePresentTym(); //This method calculates the presentTime value
display.settext(the received instruction);
}
if(presentTime.equals(expiryTime))
(make the function call)
If I do this, nothing is being displayed till presentTime and expiryTime are equal. Once they are equal, the next instruction is automatically fetched by the function call and is displayed in the TextView.
Use a a handler
Handler m_handler;
Runnable m_handlerTask ;
m_handler = new Handler();
#Override
public void run() {
// do something
m_handler.postDelayed(m_handlerTask, 1000);
}
};
m_handlerTask.run();
T0 cancel the run
m_handler.removeCallbacks(m_handlerTask); // to cancel the run
You can also use a timer but you will have to use runOnUiThread to update ui since timer runs on a different thread.
Timer _t = new Timer();
_t.scheduleAtFixedRate( new TimerTask() {
#Override
public void run() {
//do something
runOnUiThread(new Runnable() //run on ui thread
{
public void run()
{
//update ui
}
});
}
}, 1000, 1000 );
Note:
gets the next message from the server
Getting the message from server should be done on a background thread.
Edit:
While copy pasting the initialization part was missing. You have a counter i that is displayed in the textview. The counter increases by 1 every second. When it reaches 100 you cancel the run. Modify the below according to your requirements.
public class MainActivity extends Activity {
TextView tv;
Handler m_handler;
Runnable m_handlerTask ;
int i=0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv = (TextView) findViewById(R.id.textView1);
m_handler = new Handler();
m_handlerTask = new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
if(i<=100)
{
tv.setText(""+i);
i++;
}
else
{
m_handler.removeCallbacks(m_handlerTask);
}
m_handler.postDelayed(m_handlerTask, 1000);
}
};
m_handlerTask.run();
}
}
Use a timer. Schedule the timer for repeated interval executions, and after each execution you can get the next text from the server and display the same.
Check the Timer reference scheduleAtFixedRate(TimerTask task, long delay, long period)
I want to send a notification after 5 seconds.
I found this code example to do something after 5 seconds, but I just can set a Log.e().
The Notification method is also working. But if I want to call the method setNotification(), I get a RuntimeError after 5 seconds:
Can't create Handler inside Thread that has not called looper.prepare().
I found very much help, but nothing works. So I hope you can help me.
public class Reminder {
Timer timer;
public Reminder(int seconds) {
timer = new Timer();
timer.schedule(new RemindTask(), seconds * 1000);
}
}
class RemindTask extends TimerTask {
public void run() {
todo_list rem = new todo_list();
rem.setNotification("Todo!", false, 1);
}
}
public class todo_list extends ListActivity {
public void onCreate(Bundle savedInstanceState) {
new Reminder(5);
}
public void setNotification(String text, boolean ongoing, int id) {}
}
You need to call rem.setNotification from a thread which will keep running always. One way is to use runonuithread
runonUithread(new Runnable(){
run(){
rem.setNotification("Todo!",false,1);
}
});
You'll get this error when you execute some code that shouldn't be done in another thread than the UI thread. So simple get an activity object and call runOnUiThread(Runnable action) {} on it. Place that code that generates the error in the Runnable.
I hope this helps.
I'm trying to make a countdown timer in android for use in a small android app. The app will countdown from some number of seconds to 0, upon which it will do some action. I'm using the coundowntimer supplied by android.os.countdowntimer. Here is my code:
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.quizlayout);
new CountDownTimer(30000, 1000) {
TextView tx = (TextView) findViewById(R.id.textView2);
public void onTick(long millisUntilFinished) {
tx.setText("seconds remaining: " + millisUntilFinished / 1000);
}
public void onFinish() {
tx.setText("done!");
}
}.start();
}
However, this countdown timer is really slow. It takes like 3 real-time seconds for the timer to countdown by one second. I wonder what's going on? The code I have above is more or less copied straight from google (CountDownTimer)
Can anyone help me as per why my timer is so slow, and offer a way to speed it up a bit?
(EDIT): I am running this on an emulator, the intel atom x86. I am emulating an android 2.3.3 environment.
According to Android documentation for countdown timer
The calls to onTick(long) are synchronized to this object so that one call to onTick(long) won't ever occur before the previous callback is complete. This is only relevant when the implementation of onTick(long) takes an amount of time to execute that is significant compared to the countdown interval.
Take a look at this example for countdown timer
Countdown timer example
Alternately you can spawn a new thread and just get that thread to sleep for the interval you want and take actions when it wakes or vice versa.
You can also timertask
use a handler that will post the same runnable . this will remove the need for extra threads :
Handler handler=new Handler();
handler.postRunnable(... , 1000) ;
in the runnable , call the postRunnable again for the same handler (and add a condition for when to stop) .
CountDownTimer is not efficient regardless to ui updating performances. For a flawless ui update, it is better to create a custom countdown. I did my own so here it is. It is flawless on my app.
public abstract class CountDown {
int totalTime = 0;
int tickTime = 0;
Thread thread;
boolean canceled = false;
public CountDown(int totalTime,int tickTime){
this.totalTime = totalTime;
this.tickTime = tickTime;
}
public abstract void onTick();
public abstract void onFinish();
public void start(){
thread = new Thread(new Runnable() {
#Override
public void run() {
// Do in thread
canceled = false;
for (int elapsedTime = 0; elapsedTime < totalTime; elapsedTime += tickTime) {
if(!canceled){
onTick();
try {
thread.sleep(tickTime);
} catch (InterruptedException e) {
e.printStackTrace();
}
}else{
break;
}
}
if(!canceled){
onFinish();
}
}
});
thread.start();
}
public void cancel(){
canceled = true;
}
}
Remember that every time you have to update your ui, call a runOnUiThread, or else you will have an exception, you are not in a handler and not on ui thread.
Here is how to use it in your code, it is identical to CountDownTimer, so you could just rename lines in your code :
CountDown cDown = new CountDown(10000, 20) {
public void onTick() {
// Do something
}
public void onFinish() {
runOnUiThread(new Runnable() {
#Override
public void run() {
myButton.setImageDrawable(drawable);
}
});
}
};
I've got an activity that keeps reading words to the user, and using onUtteranceCompleted with textTospeech to display something when the code is completed.
Inside onUtteranceCompleted I have this code to delay a function with a second:
Runnable task = new Runnable() {
public void run() {
//runs on ui
runOnUiThread(new Runnable() {
public void run() {
readWord();
}
});
}
};
worker.schedule(task, 1, TimeUnit.SECONDS);
This seems like it works well, but I think it is causing a problem.
When I rotate the screen of my phone (I guess this starts a new activity).
I hear some words being read in the background. I guess this is because of runOnUiThread() which makes the activity continue in the background.
How could I avoid 2 activities running ? I would prefer if I don't have to stop the screen from rotating on doing some weird patch!
Thank you
EDIT:
public void readWord() {
if (this.readingOnPause) {
return;
}
txtCurrentWord.setText(currentItem[1]);
this.hashAudio.put(TextToSpeech.Engine.KEY_PARAM_UTTERANCE_ID,"word");
this.tts.setLanguage(Locale.US);
this.tts.speak(this.currentItem[1], TextToSpeech.QUEUE_FLUSH,this.hashAudio);
}
EDIT2:
instantiation of worker:
private static final ScheduledExecutorService worker = Executors.newSingleThreadScheduledExecutor();
I would use a Handler instead of runOnUiThread().
For one thing, you're using a Thread that starts another Thread - why?
Secondly, if you create a simple Handler, it should kill itself on the rotate config change. IE:
private Handler handler = new Handler() {
#Override
public void handleMessage(Message msg) {
// do your background or UI stuff
}
};
Then later use a Thread to call the handler, which will kick off whatever process you want to run on the UI thread:
new Thread() {
#Override
public void run() {
long timestamp = System.currentTimeMillis();
// thread blocks for your 1 second delay
while (System.currentTimeMillis() - timestamp <= 1000) {
// loop
}
handler.sendEmptyMessage(0);
}
}.start();
Ok so this is a fix I've come up with, if someone has a better solution, I'm listening.
I've added android:configChanges="keyboardHidden|orientation" inside the activity in the androidmanifest
2.
and then a function that is called when the screen is rotate:
#Override
public void onConfigurationChanged(Configuration newConfig)
{
super.onConfigurationChanged(newConfig);
setContentView(R.layout.streaming);
initializeUI(); //contains all the findViewByID etc...
}