返回preSS碎片问题的android [英] Back press fragments issue in android

问题描述

我有4个片段：A，B，C，D。现在我从移动A - >乙：所以我的code将

I have four Fragments: A, B, C, D. Now I am moving from A --> B so my code will be

从 A到B

getActivity().getSupportFragmentManager()
    .beginTransaction()
    .replace(R.id.content_frame, new B())
    .addToBackStack("A")
    .commit();

从 B到C 因此code将

getActivity().getSupportFragmentManager()
    .beginTransaction()
    .replace(R.id.content_frame, new C())
    .addToBackStack("B")
    .commit();

现在从 C到D 。但我不希望包括C在backstack因为背部preSS我不希望被所示的C片段。

Now from C to D. But I don't want to include C in backstack because on back press I don't want C fragment to be shown.

 getActivity().getSupportFragmentManager()
     .beginTransaction()
     .replace(R.id.content_frame, new D())
     .commit();

现在，当我preSS后退按钮，将完美高达A.如果我再次重复同样的过程现在的工作。现在再次回到上preSS由D片段，我会直接上的片段而不是将b片段发送。可以请你看着办吧，我上面code做了错误呢？

Now when I press Back button it will work perfectly upto A. Now if I repeat same process again. Now again on back press From D Fragment, I will be sent directly on A fragment instead of B fragment. Can you please figure it out the mistake that I am doing in above code?

推荐答案

下面是BackStackChangedListener的code。

Here is the code of BackStackChangedListener.

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

    fragmentManager.beginTransaction()
            .replace(R.id.content_frame, 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();
                }
            }
        }
    });
}

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