使用导航抽屉进行片段导航

Question

i actually have a little Problem with my Android App.

My App Contains a Navigation Drawer which is used to navigate inside the App. For Example

Navigation Drawer:

1. Overview
2. Search
3. Users
4. Stuff

When the App starts, i will load the Overview fragment. If the user clicks the other Items, i'll change the fragments with:

final FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.frame_container, fragment, TAG);
transaction.addToBackStack(null);
transaction.commit();

The problem was now, when the user switched, for example, from 1 > 2 > 4 > 3 and them pressing the back key, it will bring him just one fragment back. 3 > 4 > 2 > 1

So i added the code, which will bring him back to Fragment 1 on each Backpress.

public boolean onKeyDown(int keyCode, KeyEvent event) {
    int exit = 0;


    if (keyCode == KeyEvent.KEYCODE_BACK) {


        getFragmentManager().popBackStack();
        FragmentManager fm = getSupportFragmentManager();
        Fragment fragment = new Overview();
        fm.beginTransaction().add(R.id.frame_container, fragment).addToBackStack("fragBack").commit();
        return false;
    }
    return false;
}

Ok, first it was fine, but now i added some more fragments on a Deeper Level, but they should't go back to Fragment 1 on back press.

For Example

1. Overview (the Main Fragment)
2. Search (Back Key goes Back to Fragment 1)
3. Users (Back Key goes Back to Fragment 1)
4. Stuff (Back Key goes Back to Fragment 1)

4.1 Details (Back Key goes Back to Fragment 4. Stuff) < 4.1.1 More Details (Back Key goes Back to Fragment 4.1)

Would be nice if somebody has a Idea how i could handle the Navigation in my app.

Greetz

Answer 1

Your code is correct and need to change the logic. Whenever you go from the navigationdrawer, first you clear all the fragments in the stack using this code

private void clearBackStack() {
    FragmentManager manager = getSupportFragmentManager();
    manager.popBackStackImmediate(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
} 

and second, add the corresponding selected(1 or 2 or 3) fragment to the stack.

private void navigateToFragment(Fragment fragment, String TAG){
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.frame_container, fragment, TAG);
    transaction.addToBackStack(null);
    transaction.commit();
}

And when you go deeper like 2 -> 2.1 -> 2.2, on backpress you will return 2.2 ->2.1 ->2. No need to override the onKeyDown() method and add fragments again