具有回收器的 Android 嵌套片段查看

Question

我有一个嵌套片段的项目(https://github.com/checklist/NestedFragmentsRecycler)。FragmentA位于MainActivity中，包含带有适配器的RecyclerView。适配器中的每个项目都将返回FragmentB。因为我需要给一个id来装载FragmentB到位置，并且它需要是唯一的，所以我正在生成我自己的id。第一个片段显示得很好，但不幸的是，当我开始滚动时，我得到一个异常，无法找到我的唯一id:

D/FragmentManager：
android.support.v7.widget.RecyclerView{9b96575 VFEDH... F...0,0-2304,1464#7f0b0057 app： id/listView}D/FragmentManager：
android.widget.LinearLayout{e58090a V. E......-19,0-781,1464}W/ResourceType：获取资源号名称时没有包标识符0x00000001 D/FragmentManager：
android.widget.FrameLayout{c93513 V. E......0,0-800,1464#1}D/FragmentManager：
android.widget.LinearLayout{3899350 V. E......0,0-800,1464}D/FragmentManager：
android.support.v7.widget.AppCompatTextView{5f9157bV.ED....0,0-254,38#7f0b0070 app： id/text View}D/FragmentManager：
android.widget.LinearLayout{7bbcf98 V. E......781,0-1581,1464}W/Resour0,0-800,1464#2}D/FragmentManager：
android.widget.LinearLayout{c313105 V. E......0,0-800,1464}D/FragmentManager：
android.support.v7.widget.AppCompatTextView{bc7e3f1V.ED.......0,0-254,38#7f0b0070 app： id/text View}D/FragmentManager：
android.widget.LinearLayout{8f5abd6 V. E......1581,0-2381,1464}W/ResourceType：获取资源号名称时没有包标识符0x00000003 D/FragmentManager：
android.widget.FrameLayout{918d881 V. E......0,0-800,1464#3}D/FragmentManager：
android.widget.LinearLayout{651ad26 V. E......0,0-800,1464}D/FragmentManager：
android.support.v7.widget.AppCompatTextView{8798e57V.ED.......0,0-254,38#7f0b0070 app： id/text View}D/FragmentManager：
android.support.v7.widget.ActionBarContainer{36a4d44V.ED.......0,0-2560,128#7f0b0045 app： id/action_bar_container}D/FragmentManager：android.support.v7.widget.Toolbar{e65ce2d V. E......0,0-2560,128

48,37-153,91}D/FragmentManager：
android.support.v7.widget.ActionMenuView{c1eb8f3 V. E......2544,0-2544,128}D/FragmentManager：
9b{460f9b0 G. E.........0,0-0,0#7f0b0047 app： id/action_context_bar}D/FragmentManager：
Handler.java:95{77e2029android.os.Looper.loop...0,1704-2560,1800#1020030 android： id/NavigationBar}D/FragmentManager：
Looper.java:154{7365faeV.ED.......0,0-2560,48#102002f android： id/statusBarbackground}D/AndroidRuntime：关闭VM E/AndroidRuntime： FATAL EXCEPTION：主进程：example.com.demo， PID： 8156java.lang.IllegalArgumentException：找不到片段的id 0x4（未知）视图FragmentB{30cadandroid.os.Handler.dispatchMessage#3 id=0x4}在android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:1107）在android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:1295）在android.support.v4.app.BackStackRecord.run（BackStackRecord.java:801）在android.support.v4.app.FragmentManagerImpl.execPendingActions（FragmentManager.java:1682）在android.support.v4.app.FragmentManagerImpl$1.run（FragmentManager.java:541）在android.os.Handler.handleCallback（Handler.java:751）在android.support.v7.widget.ActionBarContextView（android.view.View）在V.ED.（android.view.View））在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:776）与目标VM断开连接，地址：'localhost： 8616'，传输：'ocket'

2个主要类是FragmentAAdapter和FragmentB（如果需要，您可以在git repo中查看其他类）：

public class FragmentAAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder>{

FragmentA fragmentA;
Activity activity;
RecyclerView listView;

public FragmentAAdapter(FragmentA fragmentA, Activity activity, RecyclerView listView) {
    this.fragmentA = fragmentA;
    this.activity = activity;
    this.listView = listView;
}


@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.fragment_b, parent, false);
    RecyclerView.ViewHolder vh = new BoardViewHolder(v, this);
    return vh;
}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
    if (holder instanceof BoardViewHolder){
        BoardViewHolder pHolder = (BoardViewHolder)holder;
        pHolder.onBindViewHolder(position);
    }
}

@Override
public int getItemCount() {
    return 10;
}

public class BoardViewHolder extends RecyclerView.ViewHolder {

    FragmentAAdapter adapter;
    FragmentB fragmentB;
    View view;

    public BoardViewHolder(View itemView, FragmentAAdapter adapter) {
        super(itemView);

        this.view = itemView;
        this.adapter = adapter;
    }

    public void onBindViewHolder(int position) {

        FragmentManager fm = fragmentA.getChildFragmentManager();
        if (fragmentB==null) {
            Bundle bundle = new Bundle();
            bundle.putString("TEXT", "This is Fragment B:" + position);
            fragmentB = FragmentB.getInstance(bundle);

            int boardId = generateViewId();
            // switch the id of the board to be unique
            View board = view.findViewById(R.id.board);
            board.setId(boardId);

            // now flip fragmentB
            FragmentTransaction ft = fm.beginTransaction();
            ft.replace(boardId, fragmentB);
            ft.commit();
        }
    }
}

private static final AtomicInteger sNextGeneratedId = new AtomicInteger(1);

public static int generateViewId() {
    for (;;) {
        final int result = sNextGeneratedId.get();
        // aapt-generated IDs have the high byte nonzero; clamp to the range under that.
        int newValue = result + 1;
        if (newValue > 0x00FFFFFF) newValue = 1; // Roll over to 1, not 0.
        if (sNextGeneratedId.compareAndSet(result, newValue)) {
            return result;
        }
    }
}

}

和片段B：

public class FragmentB extends Fragment {

View root;

Activity activity;

String text;
private TextView textView;

public static FragmentB getInstance(Bundle bundle) {
    FragmentB instance = new FragmentB();
    instance.setArguments(bundle);
    return instance;
}

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

    activity = (Activity) getActivity();

    if (getArguments()!=null) {
        text = getArguments().getString("TEXT");

    }
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    super.onCreateView(inflater, container, savedInstanceState);

    root = inflater.inflate(R.layout.row, null, false);

    textView = (TextView)root.findViewById(R.id.textView);
    textView.setText(text);

    return root;
}

}

完整代码：https://github.com/checklist/NestedFragmentsRecycler

谢啦！

Answer 1

经过大量的灵魂探索，我可以确认在碎片内部生成id是不可能的。如果你这样做，Android在渲染UI时会变得混乱，应用程序会崩溃。

我在另一个项目中尝试过这一点，在该项目中，我们为动态生成的单选按钮和组生成了ID，并将其放置在片段和相同的行为中。两种解决方案： - 不要以编程方式创建，因此不需要生成id - 不要使用片段