simple timer in Android
I am a complete noob and have created this simple timer:
public void RRryan(){
for (int i=0;i<5;开发者_运维知识库i++){
final Handler handler = new Handler();
Timer t = new Timer();
t.schedule(new TimerTask() {
public void run() {
handler.post(new Runnable() {
public void run() {
a();
}
});
}
}, 1000);
}
}
The function a() that it calls basically updates a text view with a ++1. But the above does not work :(
Instead of going slowly every second, it just updates it after 5 secs.
What am I doing wrong?
Thanks! Ryan
You should only need one Handler
and one Timer
. Try moving those out of the loop:
final Handler handler = new Handler();
final Timer timer = new Timer();
final Runnable doA = new Runnable() {
@Override
public void run() {
a();
}
};
public void RRryan(){
for (int i = 1; i <= 5; i++) {
TimerTask task = new TimerTask() {
@Override
public void run() {
handler.post(doA);
}
};
timer.schedule(task, i * 1000);
}
}
The schedule delays are not incremental, so make sure you actually set them to different values, otherwise they will all fire at once.
I could propose my own class for showing some clocks and dates in different views.
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import android.os.Handler;
import android.widget.TextView;
/**
* The class for creating and refreshing many different fields on different layouts,
* that can hold actual time and/or date in different formats
* The formats should be as in http://developer.android.com/reference/java/text/SimpleDateFormat.html.
* Only present and visible fields are being actualized, so there is no need to clean the clock list after closing an activity
*
* Examples of use:
*
* Clock.registerClock((TextView) findViewById(R.id.TimeField), "HH:mm");
* Clock.registerClock((TextView) findViewById(R.id.DateField), "d.M.yyyy EEE");
* Clock.start(10000L);
*
* @author Petr Gangnus
*/
public final class Clock {
/**
* the handler that works instead of timer and supports UI
*/
static private Handler handler = new Handler();
/**
* the interval of the time refreshing
*/
static private long refreshStep;
/**
* pairs TextView timer+time/date format
*/
private TextView clockFace;
private String format;
private Clock(TextView clockFace, String format){
this.clockFace=clockFace;
this.format=format;
}
// here is the list of views containing the visual timers that should be held actual
static private ArrayList<Clock> clocks=new ArrayList<Clock>();
/**
* fills all timer fields by actual time value, according to their formats.
*/
static private Runnable mUpdateTimeTask = new Runnable() {
public void run() {
for(Clock clock:clocks){
showActualTimeDate(clock);
}
handler.postDelayed(this,refreshStep);
}
};
//============================================ public members ====================================================================
/**
* add a clock to the list of updating clocks
* @param clockFace - the place where the time or date will be shown
* @param format - the format of the time/date
* @return
*/
public static boolean registerClock(TextView clockFace, String format){
if (clockFace==null) return false;
if(clocks.contains(clockFace)){
// old clockFace
clocks.get(clocks.indexOf(clockFace)).format=format;
} else {
// new clockFace
clocks.add(new Clock(clockFace, format));
}
return true;
}
/**
* remove a clock from the updating list
* @param clockFace
* @return
*/
public static boolean unRegisterClock(TextView clockFace){
if (clockFace==null) return false;
if(clocks.contains(clockFace)){
// found clockFace
clocks.remove(clocks.indexOf(clockFace));
} else {
// not found clockFace
return false;
}
return true;
}
/**
* put in the "place" the actual date/time in the appropriate "format"
* @param place
* @param format
*/
public static void showActualTimeDate(Clock clock){
if (clock.clockFace==null) return;
if (clock.clockFace.getVisibility()!=TextView.VISIBLE) return;
Date thisDate=new Date();
SimpleDateFormat df=new SimpleDateFormat(clock.format);
clock.clockFace.setText(df.format(thisDate));
}
/**
* start the ticking for all clocks
* @param step the tick interval
*/
public static void start(long step) {
refreshStep=step;
handler.removeCallbacks(mUpdateTimeTask);
handler.postDelayed(mUpdateTimeTask, 0);
}
/**
* Stopping ticking all clocks (not removing them)
* the calling could be put somewhere in onStop
*/
public static void stop() {
handler.removeCallbacks(mUpdateTimeTask);
}
}
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