how to call method in activity form non activity class

Question

I have an Activity and non Activity class. How to call a method in Activity class from non Activity class

public class MainActivity extends Activity {
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main2);

        DataClass dc = new DataClass();
        dc.show();                  
    }

    public void call(ArrayList<String> arr) {
       // Some code...
    }
}

public class DataClass {

    public void show(ArrayList<String> array) {
        // Here I want to send this ArrayList values into the call
        // method in activity class.

       MainActivity act = new MainActivity();
       act.call(array);                  
    }
}

See also http://stackoverflow.com/questions/19666572/how-to-call-a-method-in-another-activity-from-activity and http://stackoverflow.com/questions/16653867/android-call-method-from-an-other-activity — RenniePet, Dec 27 '15 at 08:27

score 14 · Answer 1 · edited Jan 21 '15 at 00:44

14

Just create a callback interface inside the DateClass.

public DateClass {
    public interface IDateCallback {
        void call(ArrayList<String> arr);
    }  

    private IDateCallback callerActivity;

    public DateClass(Activity activity) {  
        callerActivity = (IDateCallback)activity;  
    }
...  
}  

public void show(ArrayList<String> array) {            
    callerActivity.Call(array);  
    ...  
}

//And implements it inside your activity.

public class MainActivity extends Activity 
        implements IDateCallback {  

    public void call(ArrayList<String> arr) {

    }  
}

edited Jan 21 '15 at 00:44

roob

1,116
7
11

answered Oct 29 '13 at 15:50

kameny

2,372
4
30
40

Yes I think this should be the preferred way to do it. But a question regarding this approach, since we're passing an activity reference to the DateClass, won't it result in a memory leak since the activity won't be able for garbage collection because the DateClass holds a reference to it? – akshayt23 Feb 18 '16 at 13:44
Good question, to be honest I haven't got a clear answer to that question. I think it is not a problem in that case, because the activity is active and as I understand the "inner" Date class is doing something in the Activity. My assumption is: when the Activity is going to be finished, both of the classes are going to be garbaged. – kameny Feb 18 '16 at 14:30

score 7 · Answer 2 · answered Oct 29 '13 at 15:49

Well there are several things you could do. I think the easiest for you would be to send the Context into DataClass like so:

DataClass dc =new DataClass();
dc.show(this);

And in your DataClass save the context into a global var Context context. Then use it like so:

((MainActivity)context).call(array);

score 2 · Answer 3 · answered Oct 08 '16 at 09:00

2

((MainActivity)getContext).array();

answered Oct 08 '16 at 09:00

Farzam Menbary

31
3

score 0 · Answer 4 · answered Apr 28 '17 at 09:51

Just make a singleton like:

TeacherDashboardSingleton:

public class TeacherDashboardSingleton {
public  Teacher_Dashboard aa;
private static final TeacherDashboardSingleton ourInstance = new TeacherDashboardSingleton();
   public static TeacherDashboardSingleton getInstance() {
        return ourInstance;
    }
}

myActivity class:

onCreate(....){
 ....
   TeacherDashboardSingleton.getInstance().aa = this;
....
}

this will create an object of same instance as in activity

now you can use it from anywhere

how to call method in activity form non activity class

4 Answers4

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