나는 안드로이드 프래그먼트 백 스택이 작동하는 것처럼 보이는 방식에 큰 문제가 있으며 제공되는 도움에 가장 감사 할 것입니다.

3 개의 조각이 있다고 상상해보세요

[1] [2] [3]

사용자가 탐색 할 수 [1] > [2] > [3]있지만 돌아가는 중 (뒤로 버튼 누름)을 원합니다 [3] > [1].

내가 상상했듯이 XML에 정의 된 조각 홀더로 addToBackStack(..)조각을 가져 오는 트랜잭션을 만들 때 호출하지 않음으로써이 작업을 수행 할 수 있습니다 [2].

이것의 현실은 [2]사용자가 뒤로 버튼을 눌렀을 때 다시 나타나고 싶지 [3]않다면 addToBackStack프래그먼트를 보여주는 트랜잭션을 호출해서는 안되는 것 같습니다 [3]. 이것은 완전히 반 직관적 인 것처럼 보입니다 (아마도 iOS 세계에서 온 것 같습니다).

어쨌든 이렇게하면, 나가서 [1] > [2]뒤로 누르면 [1]예상대로 돌아옵니다 .

내가 가서 [1] > [2] > [3]뒤로 누르면 [1](예상대로)로 돌아갑니다 . 이제에서 [2]다시 점프하려고하면 이상한 동작이 발생 합니다 [1]. 먼저 보기 [3]전에 잠시 표시됩니다 [2]. 이 시점에서 뒤로를 누르면 [3]표시되고 다시 한 번 뒤로 누르면 앱이 종료됩니다.

아무도 여기서 무슨 일이 일어나고 있는지 이해하도록 도울 수 있습니까?

다음은 내 주요 활동에 대한 레이아웃 xml 파일입니다.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:orientation="vertical" >

<fragment
        android:id="@+id/headerFragment"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        class="com.fragment_test.FragmentControls" >
    <!-- Preview: layout=@layout/details -->
</fragment>
<FrameLayout
        android:id="@+id/detailFragment"
        android:layout_width="match_parent"
        android:layout_height="fill_parent"

        />

업데이트
이것은 탐색 계층 구조로 빌드하는 데 사용하는 코드입니다.

    Fragment frag;
    FragmentTransaction transaction;


    //Create The first fragment [1], add it to the view, BUT Dont add the transaction to the backstack
    frag = new Fragment1();

    transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.detailFragment, frag);
    transaction.commit();

    //Create the second [2] fragment, add it to the view and add the transaction that replaces the first fragment to the backstack
    frag = new Fragment2();

    transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.detailFragment, frag);
    transaction.addToBackStack(null);
    transaction.commit();


    //Create third fragment, Dont add this transaction to the backstack, because we dont want to go back to [2] 
    frag = new Fragment3();
    transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.detailFragment, frag);
    transaction.commit();


     //END OF SETUP CODE-------------------------
    //NOW:
    //Press back once and then issue the following code:
    frag = new Fragment2();
    transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.detailFragment, frag);
    transaction.addToBackStack(null);
    transaction.commit();

    //Now press back again and you end up at fragment [3] not [1]

많은 감사

답변

// transaction.replace(R.id.detailFragment, frag1);
Transaction.remove(null).add(frag1)  // frag1 on view

// transaction.replace(R.id.detailFragment, frag2).addToBackStack(null);
Transaction.remove(frag1).add(frag2).addToBackStack(null)  // frag2 on view

// transaction.replace(R.id.detailFragment, frag3);
Transaction.remove(frag2).add(frag3)  // frag3 on view

< press back button >
// System pops the back stack and find the following saved back entry to be reversed:
// [Transaction.remove(frag1).add(frag2)]
// so the system makes that transaction backward!!!
// tries to remove frag2 (is not there, so it ignores) and re-add(frag1)
// make notice that system doesn't realise that there's a frag3 and does nothing with it
// so it still there attached to view
Transaction.remove(null).add(frag1) //frag1, frag3 on view (OVERLAPPING)

// transaction.replace(R.id.detailFragment, frag2).addToBackStack(null);
Transaction.remove(frag3).add(frag2).addToBackStack(null)  //frag2 on view

< press back button >
// system makes saved transaction backward
Transaction.remove(frag2).add(frag3) //frag3 on view

< press back button >
// no more entries in BackStack
< app exits >

@Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
    if (keyCode == KeyEvent.KEYCODE_BACK)
    {
        if (getSupportFragmentManager().getBackStackEntryCount() == 0)
        {
            this.finish();
            return false;
        }
        else
        {
            getSupportFragmentManager().popBackStack();
            removeCurrentFragment();

            return false;
        }



    }

    return super.onKeyDown(keyCode, event);
}


public void removeCurrentFragment()
{
    FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();

    Fragment currentFrag =  getSupportFragmentManager().findFragmentById(R.id.detailFragment);


    String fragName = "NONE";

    if (currentFrag!=null)
        fragName = currentFrag.getClass().getSimpleName();


    if (currentFrag != null)
        transaction.remove(currentFrag);

    transaction.commit();

}

Fragment2 f2 = new Fragment2();
this.getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.main_content,f2).addToBackStack(null).commit();

Fragment3 f3 = new Fragment3();
getActivity().getSupportFragmentManager().popBackStack();
getActivity().getSupportFragmentManager().beginTransaction().replace(R.id.main_content, f3).addToBackStack(null).commit();

final FragmentActivity activity = getActivity();
activity.getSupportFragmentManager().popBackStackImmediate();
activity.getSupportFragmentManager().beginTransaction().replace(R.id.main_content, f3).addToBackStack(null).commit();

frag = new Fragment1();

transaction = getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.detailFragment, frag);
transaction.addToBackStack("Frag1");
transaction.commit();

getSupportFragmentManager().popBackStackImmediate("Frag1", 0);

fm.beginTransaction().replace(R.id.content, new CFragment()).commit()

public static void performNoBackStackTransaction(FragmentManager fragmentManager, String tag, Fragment fragment) {
  final int newBackStackLength = fragmentManager.getBackStackEntryCount() +1;

  fragmentManager.beginTransaction()
      .replace(R.id.content, fragment, tag)
      .addToBackStack(tag)
      .commit();

  fragmentManager.addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
    @Override
    public void onBackStackChanged() {
      int nowCount = fragmentManager.getBackStackEntryCount();
      if (newBackStackLength != nowCount) {
        // we don't really care if going back or forward. we already performed the logic here.
        fragmentManager.removeOnBackStackChangedListener(this);

        if ( newBackStackLength > nowCount ) { // user pressed back
          fragmentManager.popBackStackImmediate();
        }
      }
    }
  });
}

FragmentTransaction ft =getSupportFragmentManager().beginTransaction();
ft.replace(R.id.content_frame, new HomeFragment(), "Home");
ft.commit();`

Fragment home = getSupportFragmentManager().findFragmentByTag("Home");

if (home instanceof HomeFragment && home.isVisible()) {
    // do you stuff
}