Question

I think there is something that I’m just not yet getting about how these Views are to be coded. This is the third time I have had to come and post a question rearding them in the last 3 days! :S

Anyway, my problem is as follows.

edit:
This is the code inside a method that gets executed on a button press:
(Points of importance are noted)

>>  setContentView(R.layout.stop);
>>  timer = (TextView) findViewById(R.id.timer2);
    GPSMain.button = (Button) findViewById(R.id.stopbutton);

    startService(new Intent(context, Timer.class));

}

This is the Timer class that is executed in the “startService” call:
(Again points of importance are noted)

public class Timer extends Service {

static int totalSeconds = 0;
private int hour = 0;
private int min = 0;
private int sec = 0;
String mTimeFormat = "%02d:%02d:%02d";
final private Handler mHandler = new Handler();
static String timeTaken;
Context context = this;

Runnable mUpdateTime = new Runnable() {
    public void run() { updateTimeView(); }
};

@Override
public void onCreate() {

    Toast.makeText(context, "Timer Started", Toast.LENGTH_LONG).show();

    mHandler.postDelayed(mUpdateTime, 1000);
}

public void updateTimeView() {
    totalSeconds += 1;
    sec += 1;
    if(sec >= 60) {
        sec = 0;
        min += 1;
        if (min >= 60) {
            min = 0;
            hour += 1;
        }
    }
>>  timeTaken = String.format(mTimeFormat, hour, min, sec);
>>  GPSMain.timer.setText("Time Taken: "+timeTaken);
    mHandler.postDelayed(mUpdateTime, 1000);

}

@Override
public IBinder onBind(Intent intent) {
    // TODO Auto-generated method stub
    return null;
}
}

The logcat returns a NullPointerException on the following line of code:

GPSMain.timer.setText("Time Taken: "+timeTaken);

If I remove that line of code the code executes properly*, well I say properly because it executes all the way to the end of the application code, but the reason that I want to print the timer to the screen as it is counting is because I need to make sure that it is functioning correctly.

*not only does it run properly but it displays the timer text view with it’s default defined string from the xml. It’s only when I try to update it from the java that it crashes.

Here is the full xml file that the code is referencing at this point:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<Button
    android:id="@+id/stopbutton"
    android:layout_width="100px" 
    android:layout_height="100px" 
    android:text="Stop"
    android:layout_centerInParent="true"
/>
<TextView  
    android:id="@+id/timer2"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="Time Taken:       unknown"
    android:layout_below="@+id/timer"
    />
</RelativeLayout>

UPDATE!

The MyTimer Class:

@SuppressWarnings("unchecked")
public class MyTimer extends AsyncTask { 

Timer _timerTask = new Timer();
static int totalSeconds = 0, hour = 0, min = 0, sec = 0;
static String mTimeFormat = "%02d:%02d:%02d";
static String timeTakenString;

@Override
protected Object doInBackground(Object... params) {

        TimerTask timer = new TimerTask() {

            @Override
            public void run() {

                totalSeconds += 1;
                sec += 1;
                if(sec >= 60) {
                    sec = 0;
                    min += 1;
                    if (min >= 60) {
                        min = 0;
                        hour += 1;
                    }
                }
                timeTakenString = String.format(mTimeFormat, hour, min, sec);
                GPSMain.timer.setText("Time Taken: "+GPSMain.timeTaken);

            }
        };
         (_timerTask).scheduleAtFixedRate(timer,1000,1000);

    return null;
}

}

The method to start the timer thread:

void startService(){

    setContentView(R.layout.stop);

    timer = (TextView) findViewById(R.id.timer2);

    GPSMain.button = (Button) findViewById(R.id.stopbutton);

    new MyTimer().execute();

}

Answer 1

You can use TimerTask instead of Service . Here is the code ..

TimerTask timer = new TimerTask() {

            @Override
            public void run() {

                        // Here you can update your UI
    }
 }

Timer _timerTask = new Timer();
        _timerTask.scheduleAtFixedRate(timer,60000,60000);