Develop Reference

Android Root of all Activities and Fragments

How can I implement "dispatchTouchEvent(...){}" on root of my android app instead of each of activities, because I want to get when my application get sleep or in pause state.

You could create a BaseActivity where you implement it and all your activities inherit from BaseActivity:
class BaseActivity extends AppCompatActivity {
dispatchTouchEvent() {...}
}
class MyActivity extends BaseActivity {
...
}

This kind of central handling would be possible if all your activities are extended from single activity in your project. Say, AppBaseActivity contains most general functionality & all others extend it. So, events can be traced down to this AppBaseActivity. I can't predict any other way to achieve the result you want to get.

Adding functionality to the activity (inheritance, decoration, strategy ... )

I cannot decide what approach should I use in the next situtation.
One activity from my app need to have different functionality, here is the leak of multiple inheritence comes into play.
What I need to get ?
There are several parts that my activity has to have.
Navigation drawer. I am using MaterialDrawer library. It requires activity to implement on click callbacks (or use composition instead), but also it use activity as constructor argument,so I think it will be better to put this into separate class inherited from Activity or any base class provided by Android Framework . Thanks to library developer it doesn't require any stuff to be done in on create method ( setContentLayout for instance)
My activity(one of several) will have only Toolbar and FrameLayout for holding fragment . Or it is better to separate toolbar and single fragment ?
This in turn requires some stuff to be done in onCreate : setContentLayout with basic layout , add fragment to the container set activity actionbar .....
Maybe in future I will use another libraries that requires to add something in activity lifecycle methods.
All these points in order to follow Single Responsibility principle have to be separate classes inherited from some base Activity.
For example we will have something like this.
public class SingleFragmentActivity<T extends Fragment> extends AppCompatActivity {
}
public class SingleFragmentToolbarActivity<T extends Fragment> extends AppCompatActivity {
}
public class NavigationDrawerActivity extends AppCompatActivity {
}
....
As you can see each functionality is put into the separate class, but what if I need to have SingleFramgentActivity with NavigationDrawer ?
In this case I have to inherit one of these classes from another, for example
public class NavigationDrawer extends SingleFragmentActivity {
}
If to do so, I have no ability to use navigation drawer separately from SingleFragmentActivity.
What is the best practice to follow in this case, how to build class hierarchy to make it flexible and use Open-Close principle, to make changes in application without any pain. (Use strategy, decorator ..... ?)
I would be grateful everyone for help.

How to call fragment from activity without using fragmentactivity?

In my project i am using fragments and activities. in one of activity i used youtube video api, now i want to call fragment from that activity but they are not allowing without fragmentactivity and i extended youtubebaseactivity in that activity.so please help me

extend yourclass with ActionBarActivity and you can Access both functionality.
Thats it...

Android and extends about two activities

I have a problem. How I can extends for two activities. I have a activity which must extends two other activities, but I can't extends about two activities. How I can do this another way?
I need this because one activity extends Activity, but in this activity must extends MapActivity too because I'm using mapView.

In java you can not extend two classes at the same time. There are several approaches:
You can have one of the classes as a member field (lets call this A) and the other one (lets call this B) to be extended. Thus you will have access to the the private and protected methods of B and to all public methods of B. After all the main reason of extending an Activity is to get all Context's methods. From then on your own activities are just adding up methods. However, you can use them even without inheriting.
If it is possible you can make A extend B and then make your new activity extend only A. Thus all the methods of both activities will be inherited.
EDIT After your edit I can say you are already in case 2 of my explanation. MapActivity is an Activity by itself. You need not extend both. Extend just MapActivity.

MapActivity extends Activity, so you just have to inherit from MapActivity.
class YourClass extends MapActivity

How to use multilevel inheritance in android

I am making an app in which i have to run an activity in background until the app is running.each activity related to this app is using first activity.how can it possible?
can i use the inheritance for this?
can anyone tell me any example of multilevel interitance in android?

You can create a BaseActivity class that extends Activity and all other Activities will extend this BaseActivity. Then what ever happened in all other activities (like resume and pause) will also effect the actions of BaseActivity.
If you have to accomplish background task you better to see android service

You are already extending the Activity class in a base class, and again you are extending this base class in other class. This is itself an example of multilevel inheritance. I am posting an example that may be relevant for your question:
public class basecls extends Activity{
/*The base class*/
}
public class secondcls extends basecls{
/* basecls extended by secondcls */
}
You can extend the secondcls in another class, and the new class will inherit all super classes such that you can use the methods of its super classes.

Your main activity is already using inheritance, since it extends the Activity class.