Develop Reference

Best practice to create a thread that runs every hour in Android?

So I'm attempting to create background task that needs to be run every hour in an Android app. Its a rather heavy task that takes around 5 - 10 minutes to finish, and right now it runs on the UI thread which of course isn't good, because it hangs the whole application. I've attempted the following in my MainActivity onCreate:
new Thread(new Runnable() {
private Handler HeavyTaskHandler = new Handler(Looper.getMainLooper());
public void run(){
final TextView updatedTxt = findViewById(R.id.txt);
updatedTxt.post(new Runnable() {
#Override
public void run() {
updatedTxt.setText("Performing cleanup..");
}
});
HeavyTask(); // <-- This method runs for 5 - 10 minutes
updatedTxt.post(new Runnable() {
#Override
public void run() {
updatedTxt.setText("Done..");
}
});
HeavyTaskHandler.postDelayed(this, HeavyTaskCycle);
}
}).start();
I have two issues with the above
It works fine the first time, and the task is performed in the background well without hanging the UI thread. However, after this first time and the next time(s) it is run, the UI thread hangs again when it is run. What am I missing?
Notice that before the HeavyTask() method is called i try to set a TextViews text to "Performing cleanup.." .. This never shows, only the "Done.." which happens after the HeavyTask() method is done. How can i ensure that the message also appears before?

I ended up doing the following from MainActivity which doesn't hang the application
private void CreateCleanUpThread()
{
CleanUpThread = new Thread(new Runnable() {
public void run(){
try {
while(true) {
performingCleanup = true;
final TextView updatedTxt = findViewById(R.id.updated_txt);
runOnUiThread(new Runnable() {
#Override
public void run() {
updatedTxt.setText("Performing database history cleanup..");
}
});
HeavyTask(); // <-- This method runs for 5 - 10 minutes
runOnUiThread(new Runnable() {
#Override
public void run() {
updatedTxt.setText("Done..");
}
});
performingCleanup = false;
Thread.sleep(CleanUpCycle); // 1 hour wait time
}
} catch(Exception ex) {
System.out.println("Error in CreateCleanUpThread : " + ex.getMessage());
}
}
});
}
// onCreate in MainActivity
...
CleanUpThread.start();
Certainly not the best way, but it works and will do for now. Should be moved to a service instead i think.

How can I control a timer in android?

I want to make an application about mini game.
Detail : In 2 seconds you must to answer a question if you don't answer or the answer is wrong -> Game Over . But if your answer is true the Timer will reset become 0 and countdown again with diffirent question.
I have already seen many code about timer in website but I don't understand clearly about it :(
So I want to ask : How can i set up a timer run only 2 seconds and how can i reset it and continue with a new question ?
Please help me.

you can use CountDownTimer in android like this:
public class Myclass {
myTimer timer =new myTimer(2000,1000);
public void creatQuestion(){
timer.start();
//method you init question and show it to user
}
public void getUserAnswer(/*evry thing you expected*/)
{
//if answer is true call timer.start()
//else call timer.onFinish(); to run onfinish in timer
}
public class myTimer extends CountDownTimer {
public myTimer(long millisInFuture, long countDownInterval) {
super(millisInFuture, countDownInterval);
}
#Override
public void onTick(long millisUntilFinished) {
// you can update ui here
}
#Override
public void onFinish() {
this.cancel();
//fire game over event
}
}
}
i hope it make you satisfy

I've done something similar using Thread/Runnable.
Thread t = new Thread(new Runnable() {
public void run() {
final long startTime = getTime();
final long maxEndTime = startTime + 2000L;
try {
while (shouldContinueWaiting()) {
if (getTime() > maxEndTime) {
throw new TimeoutException();
}
sleep();
}
} catch (InterruptedException e) {
handleInterrupt();
} catch (TimeoutException e) {
handleTimeout();
}
}
boolean shouldContinueWaiting() {
// Has the user already answered?
}
void handleInterrupt() {
// The user has answered. Dispose of this thread.
}
void handleTimeout() {
// User didn't answer in time
}
void sleep() throws InterruptedException {
Thread.sleep(SLEEP_DURATION_IN_MILLIS);
}
void getTime() {
return System.currentTimeMillis();
}
then you can start/restart the thread by:
t = new Thread(same as above...);
t.start();
and stop by:
t.interrupt();

We want to use the Timer class.
private Timer timer;
When you're ready for the timer to start counting -- let's say it's after you press a certain button -- do this to start it:
timer = new Timer();
timer.scheduleAtFixedRate(incrementTime(), 0, 100);
The first line is us creating a new Timer. Pretty standard. The second line, however, is the one I wanted you to see.
incrementTime() is a method that is called at the end of every "tick" of the clock. This method can be called whatever you want, but it has to return an instance of TimerTask. You could even make an anonymous interface if you want, but I prefer moving it off into its own section of code.
The 0 is our starting location. We start counting from here. Simple.
The 100 is how large a "tick" of the clock is (in milliseconds). Here, it's every 100 milliseconds, or every 1/10 of a second. I used this value at the time of writing this code because I was making a stopwatch application and I wanted my clock to change every 0.1 seconds.
As for your project, I'd suggest making the timer's task be your question switch method. Make it happen every 2000 milliseconds, or 2 seconds.

You can use a Handler.
Handler h = new Handler();
h.postDelayed(new Runnable() {
#Override
public void run() {
//this will happen after 2000 ms
}
}, 2000);

Maybe this can help you:
Handler handler = new Handler();
handler.post(new Runnable() {
#Override
public void run() {
// FIRE GAME OVER
handler.postDelayed(this, 2000); // set time here to refresh textView
}
});
You can fire your game over after 2000 milliseconds.
If you get the question correct -> remove callback from handler and reset it when the next question starts.

I cant make myHandler run

What I want to do is just a basic implementation of handler example. I have a TextView on the mainActivity, and once the page loads the handler is supposed to run and show the user value coming from SystemClock.uptimeMillis. But ıt doesn't work more than once. How can I make this code run?
public class MainActivity extends Activity {
long uptoMS=0L;
TextView tv;
Handler handler=new Handler();
long swaptime=0L;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv=(TextView)findViewById(R.id.textView1);
uptoMS=SystemClock.uptimeMillis();
tv.setText(String.valueOf(uptoMS));
handler.post(runner);
}
private Runnable runner=new Runnable() {
#Override
public void run() {
// TODO Auto-generated method stub
swaptime+=uptoMS;
tv.setTag(String.valueOf(swaptime));
handler.post(this);
}
};
}

See this below example
scheduler(){
TimerTask tasknew = new TimerSchedulePeriod();
Timer timer = new Timer();
// scheduling the task at interval
timer.schedule(tasknew,100, 100);
}
// this method performs the task
public void run() {
System.out.println("timer working");
}

timer = new Timer();
refreshTask = new TimerTask() {
#Override
public void run() {
swaptime+=uptoMS;
tv.setTag(String.valueOf(swaptime));
handler.post(this);
}
};
timer.schedule(refreshTask,
100, 100);

Well, there some problems with your code.
Firstly, you use setTag() instead of setText(), so the value will never update.
tv.setTag(String.valueOf(swaptime));
Secondly, you get uptoMS once in onCreate(), and then you use it in every "handler loop". I don't know what you try to achive but it's unlike that you want this.
Thirdly, you instantly repost your Runnable, so the main thread's message queue will be busy. You should give some break instead of instant reposting. For example you can wait 100 ms between the updates, so the TextView will be updated 10 times in every second.
handler.postDelayed(this, 100);
And finally, however others suggest you using Timer, just ignore them. Handler is the Android way to achieve tasks like this.

schedule an asynctask after a variable time duration every time in android?

I am using a timeschedular in android to schedule an AsyncTask in my app.I was able to work it out well,now i want every time the duration after which the task runs to be changed i am using this code
ip=3000;
final Handler handler = new Handler();
Timer timer = new Timer();
TimerTask doAsynchronousTask = new TimerTask() {
#Override
public void run() {
handler.post(new Runnable() {
public void run() {
try {
play_duration=durat.get(vn);
ip=Integer.valueOf(play_duration);
ip=ShowImages.ip*1000;
Showtime s1 = new Showtime();
s1.execute(what,f12,transi,play_duration);
} catch (Exception e) {
// TODO Auto-generated catch block
}
}
});
}
};
timer.schedule(doAsynchronousTask, 0,ip);
i am trying to change the value of ip variable every time in the thread but it do not change and i do not know why my thread always run after the initial value of ip that is 3000 miliseconds, can someone suggest a way to do it..thanks

to change component on the UI use the runOnUiThread,
see here, here and here to do that thing on the background you can use something like -
while(true)
{
runOnUiThread() {
do some stuf here;
}
Thread.Sleep(300); //<--- that should be nothing for the user and enough for the cpu
}
if you need more accurate answer post your code and ill guide you through

Updating UI on button click after a certain time

I have a TextView. I want to update its text (append a "1") after 1 second of a button click.
public class HaikuDisplay extends Activity {
Method m;
Timer t;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
t = new Timer();
m = HaikuDisplay.class.getMethod("change");
}
//Event handler of the button
public void onRefresh(View view)
{
//To have the reference of this inside the TimerTask
final HaikuDisplay hd = this;
TimerTask task1 = new TimerTask(){
public void run(){
/*
* I tried to update the text here but since this is not the UI thread, it does not allow to do so.
*/
//Calls change() method
m.invoke(hd, (Object[])null);
}
};
t.schedule(task1, 1000);
}
public void change()
{
//Appends a "1" to the TextView
TextView t = (TextView)findViewById(R.id.textView1);
t.setText(t.getText() + "1");
}
//Event handler of another button which updates the text directly by appending "2".
//This works fine unless I click the first button.
public void onRefresh1(View view)
{
TextView t = (TextView)findViewById(R.id.textView1);
t.setText(t.getText() + "2");
}
}
Consider all Exceptions be handled.
On first click, m.invoke gives InvocationTargetException. But it calls the method change() on successive invokes without any Exceptions(verified by logging). But it does not update the text. Where am I wrong?
Also, I see in the debugger that it creates a new Thread every time I click the button. That is fine. But why isn't it removing the previous Threads though their execution has been completed?

Do something like this
public void onRefresh1(View v) {
// You can have this in a field not to find it every time
final EditText t = (EditText) findViewById(R.id.textView1);
t.postDelayed(new Runnable() {
#Override
public void run() {
t.append("1");
}
}, 1000);
}

new Handler().postDelayed(new Runnable() {
#Override
public void run() {
// Update UI
}
}, 1000);
implement this on button click
UPDATE:
There are some other answers. dtmilano suggested another solution which is almost same to mine except he is calling the postDelayed method of View class and In my answer I used postDelayed method of handler class.
from the api reference of android the postDelayed method of Handler says
The runnable will be run on the thread to which this handler is
attached.
and the postDelayed method of View says
The runnable will be run on the user interface thread.
This is the only difference between these two solution. in my answer instead of creating new Handler every time you can use any other handler instance. Then the runnable will be run on that thread where that specific handler is declared. And if the postDelayed of EditText is used the the runnable method will be run on the user Interface Thread.
Now the performance issue, both has the same performance (If anybody can prove me wrong with reference I will be happy)

That's looking awful convoluted - have you considered using CountDownTimer instead?
new CountDownTimer(1000, 1000) {
public void onTick(long millisUntilFinished) {
// no-op
}
public void onFinish() {
change();
}
}.start();
This should call change (and hence change the text) on the UI thread, avoiding reflection and threading errors.

Hi Use the following code for that. Hope this will help you .
new java.util.Timer().schedule(
new java.util.TimerTask() {
#Override
public void run() {
// your code here
}
},
1000
);
Have a look of this question also.
display data after every 10 seconds in Android
You can try with this also.
private Handler handler = new Handler();
private Runnable runnable = new Runnable() {
public void run() {
doStuff();
/*
* Now register it for running next time
*/
handler.postDelayed(this, 1000);
}
};
**EDIT 3**
Try with this once you are need to enable once (i mean if you put your code in yourmethod()== this will get automatically call 1 seconds once.
private Timer timer;
TimerTask refresher;
// Initialization code in onCreate or similar:
timer = new Timer();
refresher = new TimerTask() {
public void run() {
yourmethod();
};
};
// first event immediately, following after 1 seconds each
timer.scheduleAtFixedRate(refresher, 0,100);