问题
I\'m developing an Android 2.3.3 application and I need to run a method every X seconds.
In iOS, I have NSTimer, but in Android I don\'t know what to use.
Someone have recommend me Handler; another recommend me AlarmManager but I don\'t know which method fits better with NSTimer.
This is the code I want to implement in Android:
timer2 = [
NSTimer scheduledTimerWithTimeInterval:(1.0f/20.0f)
target:self
selector:@selector(loopTask)
userInfo:nil
repeats:YES
];
timer1 = [
NSTimer scheduledTimerWithTimeInterval:(1.0f/4.0f)
target:self
selector:@selector(isFree)
userInfo:nil
repeats:YES
];
I need something what works like NSTimer.
What do you recommend me?
回答1:
This really depends on how long apart you need to run the function.
If it is => 10 minutes → I would go with Alarm Manager.
// Some time when you want to run
Date when = new Date(System.currentTimeMillis());
try{
Intent someIntent = new Intent(someContext,MyReceiver.class); // intent to be launched
// note this could be getActivity if you want to launch an activity
PendingIntent pendingIntent = PendingIntent.getBroadcast(
context,
0, // id, optional
someIntent, // intent to launch
PendingIntent.FLAG_CANCEL_CURRENT); // PendintIntent flag
AlarmManager alarms = (AlarmManager) context.getSystemService(
Context.ALARM_SERVICE);
alarms.setRepeating(AlarmManager.RTC_WAKEUP,
when.getTime(),
AlarmManager.INTERVAL_FIFTEEN_MINUTES,
pendingIntent);
}catch(Exception e){
e.printStackTrace();
}
And then you receive these broadcasts via broadcast receiver. Note that this will need to be registered ether in your application manifest or via context.registerReceiver(receiver,filter); method For more information on Broadcast Receivers please refer to official Docs. Broadcast Receiver.
public class MyReceiver extends BroadcastReceiver{
@Override
public void onReceive(Context context, Intent intent)
{
//do stuffs
}
}
If it is =< 10minutes → I would go with a Handler.
Handler handler = new Handler();
int delay = 1000; //milliseconds
handler.postDelayed(new Runnable(){
public void run(){
//do something
handler.postDelayed(this, delay);
}
}, delay);
回答2:
Use Timer for every second...
new Timer().scheduleAtFixedRate(new TimerTask() {
@Override
public void run() {
//your method
}
}, 0, 1000);//put here time 1000 milliseconds=1 second
回答3:
You can please try this code to call the handler every 15 seconds via onResume() and stop it when the activity is not visible, via onPause().
Handler handler = new Handler();
Runnable runnable;
int delay = 15*1000; //Delay for 15 seconds. One second = 1000 milliseconds.
@Override
protected void onResume() {
//start handler as activity become visible
handler.postDelayed( runnable = new Runnable() {
public void run() {
//do something
handler.postDelayed(runnable, delay);
}
}, delay);
super.onResume();
}
// If onPause() is not included the threads will double up when you
// reload the activity
@Override
protected void onPause() {
handler.removeCallbacks(runnable); //stop handler when activity not visible
super.onPause();
}
回答4:
If you are familiar with RxJava, you can use Observable.interval(), which is pretty neat.
Observable.interval(60, TimeUnits.SECONDS)
.flatMap(new Function<Long, ObservableSource<String>>() {
@Override
public ObservableSource<String> apply(@NonNull Long aLong) throws Exception {
return getDataObservable(); //Where you pull your data
}
});
The downside of this is that you have to architect polling your data in a different way. However, there are a lot of benefits to the Reactive Programming way:
- Instead of controlling your data via a callback, you create a stream of data that you subscribe to. This separates the concern of "polling data" logic and "populating UI with your data" logic so that you do not mix your "data source" code and your UI code.
With RxAndroid, you can handle threads in just 2 lines of code.
Observable.interval(60, TimeUnits.SECONDS) .flatMap(...) // polling data code .subscribeOn(Schedulers.newThread()) // poll data on a background thread .observeOn(AndroidSchedulers.mainThread()) // populate UI on main thread .subscribe(...); // your UI code
Please check out RxJava. It has a high learning curve but it will make handling asynchronous calls in Android so much easier and cleaner.
回答5:
new CountDownTimer(120000, 1000) {
public void onTick(long millisUntilFinished) {
txtcounter.setText(" " + millisUntilFinished / 1000);
}
public void onFinish() {
txtcounter.setText(" TimeOut ");
Main2Activity.ShowPayment = false;
EventBus.getDefault().post("go-main");
}
}.start();
回答6:
Here I used a thread in onCreate() an Activity repeatly, timer does not allow everything in some cases Thread is the solution
Thread t = new Thread() {
@Override
public void run() {
while (!isInterrupted()) {
try {
Thread.sleep(10000); //1000ms = 1 sec
runOnUiThread(new Runnable() {
@Override
public void run() {
SharedPreferences mPrefs = getSharedPreferences("sam", MODE_PRIVATE);
Gson gson = new Gson();
String json = mPrefs.getString("chat_list", "");
GelenMesajlar model = gson.fromJson(json, GelenMesajlar.class);
String sam = "";
ChatAdapter adapter = new ChatAdapter(Chat.this, model.getData());
listview.setAdapter(adapter);
// listview.setStackFromBottom(true);
// Util.showMessage(Chat.this,"Merhabalar");
}
});
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
};
t.start();
In case it needed it can be stoped by
@Override
protected void onDestroy() {
super.onDestroy();
Thread.interrupted();
//t.interrupted();
}
回答7:
With Kotlin, we can now make a generic function for this!
object RepeatHelper {
fun repeatDelayed(delay: Long, todo: () -> Unit) {
val handler = Handler()
handler.postDelayed(object : Runnable {
override fun run() {
todo()
handler.postDelayed(this, delay)
}
}, delay)
}
}
And to use, just do:
val delay = 1000L
RepeatHelper.repeatDelayed(delay) {
myRepeatedFunction()
}
回答8:
Here maybe helpful answer for your problem using Rx Java & Rx Android.
来源：https://stackoverflow.com/questions/11434056/how-to-run-a-method-every-x-seconds