Activity for a screen calls itself for similar usages - but going back quits app

I have one activity representing a screen that is used in two variations. The only difference is that in one case it's used to handle numbers in the other for colors. This is how it is declared:

> public class MainScreen extends Activity {
    /** Called when the activity is first created. */

    private Integer activityCode; 
    private static final int ACTIVITY_NUMBER = 0;
    private static final int ACTIVITY_COLOR = 1;

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            activityCode开发者_Python百科 = savedInstanceState != null ? savedInstanceState
                    .getInt("Task") : null;
            if (activityCode == null) {
                Bundle extras = getIntent().getExtras();
                activityCode = extras != null ? extras.getInt("Task") : null;
            }   
            do stuff depending on which activity is actually chosen
        }

And this is how it is called

FROM WITHIN ITSELF

:

> @Override
    public boolean onMenuItemSelected(int featureId, MenuItem item) {
        Intent i;
        switch (item.getItemId()) {
        case OTHER_PAGE_ID:
            i = new Intent(this, MainScreen.class);
            if (activityCode == ACTIVITY_NUMBER) {
                i.putExtra("Task", ACTIVITY_COLOR);
                startActivityForResult(i, ACTIVITY_COLOR);
                finish();
            } else {
                i.putExtra("Task", ACTIVITY_NUMBER);
                startActivityForResult(i, ACTIVITY_NUMBER);
                finish();
            }

            return true;

        ....

        }

Is this way of re-using the same class actually OK? I use the same class for very similar screens and want to switch back and forth depending on the user selection.

BUT the class calls itself everytime a different screen is selected between NUMBERS <-> COLOR.

The problem is, that when I go from NUMBERS to COLORS and then press back-arrow the app quits. However, when I go from NUMBERS to another screen and press back, it goes back to NUMBERS again.

Why doesn't going back to where I come from work in the case where the class calls itself? I would assume it just puts each call on the stack and comes back to it.

Isn't this just a mini recursion where NUMBER calls itself as COLOR and when finished appears again?

I hope I could make myself clear. Thanks for your help

That makes my head spin. Why not just use two Activities? If it's for code reuse, just have one base class with all your common code, then extend it for your Colour and Number classes:

public class Base extends Activity {
    // common code here
}

public class Colour extends Base {
    // colour specific code here
}

public class Number extends Base {
    // number specific code here
}