在一定时间段后改变活动

Question

I am creating app that changes activities after time period, but I can`t make it work. When I run the program I get only black screen. Here is my onCreate method:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    context = this;
activity = 1;
     i = new Intent(context, WeatherActivity.class);
    Handler mHandler = new Handler();
    mHandler.postDelayed(new Runnable() {

        @Override
        public void run() {
            while (true){
             if(activity ==1){
                 context.startActivity(i);
                 activity = 0;
             }else if (activity ==0){
                 news();

                 activity = 1;
             } try {
                    Thread.sleep(10000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
        }


        }

    }, 10000L);
}

Activities are just simple activies with just some text. I`ll post them if needed. Edit: Made it work by changin activities in methods.

Answer 1

You are missing setContentView

super.onCreate(savedInstanceState);
setContentView(R.layout.your_xml_name);

Check

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.your_xml_name);
context = this;
activity = 1;

Check Splash screen

Answer 2

To get things done in tandem you can use AlarmManager.

    Intent intent = new Intent("com.foo.android.MY_TIMER");
    PendingIntent pendingIntent = PendingIntent.getBroadcast(this, 0, intent, 0);
    AlarmManager manager = (AlarmManager) getSystemService(ALARM_SERVICE);
    long now = System.currentTimeMillis();
    long interval = 60 * 60 * 1000; // 1 hour
    manager.setRepeating(AlarmManager.RTC_WAKEUP, now + interval, interval,
        pendingIntent); // Schedule timer for one hour from now and ev

Then extends BroadcastReceiver add to your activity .

public class YourActivity extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {
     // your task

}

}

RegisterReceiver your BroadcastReceiver @Override protected void onResume() { super.onResume(); mIntentFilter=new IntentFilter("com.foo.android.MY_TIMER"); registerReceiver(mReciever, mIntentFilter); }

Remember to run this in the onDestroy method:

@Override
protected void onDestroy() {
  super.onDestroy();
  unregisterReceiver(receiver);
}

Answer 3

Well, I suppose your problem is that you are executing an infinite loop in the main thread, it will never have the opportunity to draw the new activity layout.

A possible solution is to use AsyncTask described here .

Essentially, it allows you to perform long running task in background and to publish results on the main thread when they are ready.

class MyAsyncTask extends AsyncTask<Integer, Void, Void> { 
     private Context context;

     public MyAsyncTask(Context c) { context = c; }

     public void doInBackground(Integer... milliseconds) {
          try {
              for(int i = 0; i < milliseconds.length; ++i)
                  Thread.sleep(milliseconds[i]);
          } catch (InterruptedException e) {
                e.printStackTrace();
          }
     }

     public void onPostExecute(Void result) {
         Intent intent = new Intent(context, WeatherActivity.class);
         context.startActivity(intent);
     }
}

Now you just have to instantiate and execute it where you want:

new MyAyncTask(context).execute(100000);

You can do also more complicated things with AsyncTask , like publishing intermediate results with publishProgress and onProgressUpdate (see the documentation for more information), this was just a basic example.