没有使用 FirebaseRecyclerAdapter 填充数据？答案

【问题标题】：Data is not getting populated using FirebaseRecyclerAdapter?没有使用 FirebaseRecyclerAdapter 填充数据？
【发布时间】：2016-03-30 03:36:15
【问题描述】：

我正在尝试将数据填充到 RV。如果我使用自定义适配器（RV 的传统适配器）来实现。数据正在被填充。但我想使用FirebaseRecyclerAdapter。这样我就可以减少一些样板代码。在实施时我得到Failed to bounce to type 错误。

来自 Firebase 的 JSON

{
  "subscriptions" : {
    "obama@gmsil,com" : {
      "-KDnfjROKeFAL9wccsxY" : {
        "category" : "Mobility",
        "goal" : "afternoon body weight workout",
        "length" : 1,
        "title" : "Afternoon HiiT",
        "weeks" : {
          "week1" : [ "High Knees", "Squats", "Lunges", "Diamond Push-ups", "Lying Triceps Lifts" ]
        }
      }
    }
  }
}

Program.java

public class Program {
    private String title;

    private String goal;

    private String category;

    private int length;

    HashMap<String, ArrayList<String>> weeks;

    public Program() {
    }

    public Program(String title, String goal,  String category, int length, HashMap<String, ArrayList<String>> weeks) {
        this.title = title;
        this.goal = goal;
        this.category = category;
        this.length = length;
        this.weeks = weeks;
    }

    public String getTitle() {
        return title;
    }

    public String getGoal() {
        return goal;
    }

    public String getCategory() {
        return category;
    }
    public int getLength() {
        return length;
    }
    public HashMap<String, ArrayList<String>> getweeks() {
        return weeks;
    }    
}

片段代码

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

        View v = inflater.inflate(R.layout.fragment_latest, container, false);

        mRecyclerView = (RecyclerView) v.findViewById(R.id.recycler_view);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

        mAdapter = new FirebaseRecyclerAdapter<Program, ProgramVH>(Program.class, R.layout.program_item, ProgramVH.class, mRef) {
            @Override
            public void populateViewHolder(final ProgramVH programViewHolder, Program mProgram, int position) {
                programViewHolder.setName(program.getTitle());
                programViewHolder.level.setText(program.getLength());

            }
        };
        mRecyclerView.setAdapter(mAdapter);
        FetchData();
        return v;
    }

public void FetchData(){

        mRef.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                if (dataSnapshot.exists()) {
                    for (DataSnapshot userSnapshot : dataSnapshot.getChildren()) {
                        for (DataSnapshot programSnapshot : userSnapshot.getChildren()) {
                            program = programSnapshot.getValue(Program.class);
                            Log.e("VH", program.getTitle());  // Title is getting printed
                        }
                    }
                }
                mAdapter.notifyDataSetChanged();
            }

            @Override
            public void onCancelled(FirebaseError firebaseError) {
            }
        });

    }

    @Override
    public void onDestroyView() {
        super.onDestroyView();
        mAdapter.cleanup();
    }

ViewHolder

public static class ProgramVH extends RecyclerView.ViewHolder {
        protected ImageView header;
        protected TextView title;
        protected TextView level;

        public ProgramVH(View view) {
            super(view);
            this.header = (ImageView) view.findViewById(R.id.coverImage);
            this.title = (TextView) view.findViewById(R.id.title);
            this.level = (TextView) view.findViewById(R.id.level);
        }

        public void setName(String name) {
            title.setText(name);
        }
    }

堆栈跟踪

08:55:19.045 5717-5717/com.android.sam E/VH：下午 HiiT 03-30 08:55:19.045 5717-5717/com.android.sam D/AndroidRuntime: 关闭 VM03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 致命异常: main 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 致命异常: main 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 进程: com.android.sam, PID: 5717 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: com.firebase.client.FirebaseException: 无法弹回输入 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 com.firebase.client.DataSnapshot.getValue(DataSnapshot.java:185) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 com.firebase.ui.FirebaseRecyclerAdapter.parseSnapshot(FirebaseRecyclerAdapter.java:161) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 com.firebase.ui.FirebaseRecyclerAdapter.getItem(FirebaseRecyclerAdapter.java:150) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 com.firebase.ui.FirebaseRecyclerAdapter.onBindViewHolder(FirebaseRecyclerAdapter.java:190) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:5465) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:5498) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4735) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:4611) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:1988) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1384) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1347) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:574) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3026) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:2903) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3277) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.View.layout(View.java:15686) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.ViewGroup.layout(ViewGroup.java:5039) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.design.widget.CoordinatorLayout.layoutChild(CoordinatorLayout.java:1087) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.design.widget.CoordinatorLayout.onLayoutChild(CoordinatorLayout.java:797) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.design.widget.ViewOffsetBehavior.layoutChild(ViewOffsetBehavior.java:63) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.design.widget.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:126) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.design.widget.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:42) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1139) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:810) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.View.layout(View.java:15686) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.ViewGroup.layout(ViewGroup.java:5039) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.v4.view.ViewPager.onLayout(ViewPager.java:1684) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.View.layout(View.java:15686) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.ViewGroup.layout(ViewGroup.java:5039) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.design.widget.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:122) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.design.widget.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:42) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1139) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:810) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.View.layout(View.java:15686) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.ViewGroup.layout(ViewGroup.java:5039) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.widget.FrameLayout.layoutChildren(FrameLayout.java:579) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.widget.FrameLayout.onLayout(FrameLayout.java:514) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.View.layout(View.java:15686) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.ViewGroup.layout(ViewGroup.java:5039) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.widget.RelativeLayout.onLayout(RelativeLayout.java:1077) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.View.layout(View.java:15686) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.ViewGroup.layout(ViewGroup.java:5039) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1183) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.View.layout(View.java:15686) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.ViewGroup.layout(ViewGroup.java:5039) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.widget.FrameLayout.layoutChildren(FrameLayout.java:579) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.widget.FrameLayout.onLayout(FrameLayout.java:514) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.View.layout(View.java:15686) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.view.ViewGroup.layout(ViewGroup.java:5039) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: 在 android.widget.LinearLayout.onLayout(LinearLayout.java:1466) 03-30 08:55:19.045 5717-5717/com.android.sam E/AndroidRuntime: at android.view.View

更新

如果我使用下面的ref，数据就会被填充

Firebase mRef = new Firebase("https://arulnadhan.firebaseio.com/").child("subscriptions/obama@gmsil,com");

但是当我使用下面的ref 和 FetchData() 方法时它不起作用！

Firebase mRef = new Firebase("https://arulnadhan.firebaseio.com/subscriptions");

public void FetchData(){

        mRef.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                if (dataSnapshot.exists()) {
                    for (DataSnapshot userSnapshot : dataSnapshot.getChildren()) {
                        for (DataSnapshot programSnapshot : userSnapshot.getChildren()) {
                            program = programSnapshot.getValue(Program.class);
                            Log.e("VH", program.getTitle());  // Title is getting printed
                        }
                    }
                }
                mAdapter.notifyDataSetChanged();
            }

            @Override
            public void onCancelled(FirebaseError firebaseError) {
            }
        });
    }

**订阅节点下的JSON **

{
  "arulndhan@gmail,com" : {
    "-KDnhRwHjssOejrqyenP" : {
      "category" : "Strength",
      "goal" : "This workout can be done while on the phone!",
      "length" : 1,
      "title" : "Hello Workouts",
      "weeks" : {
        "week1" : [ "High Knees", "Jumping Jacks", "Wall sit", "Pushups", "Sit-ups", "Step ups", "Squats", "Tricep dips on chair", "Plank", "High Knees running in place", "Lunges", "Pushup and rotation", "Side plank (alternate per round)", "Alternating Push-Up Plank", "Chest Expander", "Diamond Push-ups", "Dive Bomber Push-ups", "Butt Kickers", "Lying Triceps Lifts", "One Arm Side Push-up", "Overhead Arm Clap", "Overhead Press", "Power Circles", "Push-up and Rotation", "T Push-ups", "Reverse Plank", "Spiderman Push-up", "T Raise", "Tricep Dips", "Wall Push-ups", "Wide Arm Push-ups", "Burpees" ]
      }
    },
    "-KDni3TN4NMyGXePyp92" : {
      "category" : "Strength",
      "goal" : "This workout can be done by a BABUJI",
      "length" : 1,
      "title" : "Indian Workouts",
      "weeks" : {
        "week1" : [ "Diamond Pushups", "Jackknives", "Plyo Lunges", "Plyo Squats", "Single leg plank (alternate per round)", "Plyo Lunges", "Pushup and rotation", "Weighted side plank (alternate per round)", "Alternating Push-Up Plank", "Chest Expander", "Diamond Push-ups", "Dive Bomber Push-ups", "One Arm Side Push-up", "Overhead Press", "Push-up and Rotation", "T Push-ups", "Spiderman Push-up", "Wide Arm Push-ups", "Burpee Pushups" ]
      }
    }
  },
  "obama@gmsil,com" : {
    "-KDnfjROKeFAL9wccsxY" : {
      "category" : "Mobility",
      "goal" : "afternoon body weight workout",
      "length" : 1,
      "title" : "Afternoon HiiT",
      "weeks" : {
        "week1" : [ "High Knees", "Squats", "Lunges", "Diamond Push-ups", "Lying Triceps Lifts" ]
      }
    },
    "-KDps90Dn6XtJc6Co00b" : {
      "category" : "Strength",
      "goal" : "goal",
      "length" : 1,
      "title" : "title",
      "weeks" : {
        "week1" : [ "Diamond Pushups", "Jackknives", "Plyo Lunges", "Plyo Squats", "Single leg plank (alternate per round)", "Plyo Lunges", "Pushup and rotation", "Weighted side plank (alternate per round)", "Alternating Push-Up Plank", "Chest Expander", "Diamond Push-ups", "Dive Bomber Push-ups", "One Arm Side Push-up", "Overhead Press", "Push-up and Rotation", "T Push-ups", "Spiderman Push-up", "Wide Arm Push-ups", "Burpee Pushups" ]
      }
    }
  }
}

【问题讨论】：

你为什么打电话给mRef.addListenerForSingleValueEvent() inside populateViewHolder()？这对我来说没有任何意义。我强烈建议您退后几步，首先关注FirebaseUI codelab。
我遵循了 chatMessage 示例。但是看到这个答案后，我在populateViewHolder()stackoverflow.com/a/34561726/2781359
https://arulnadhan.firebaseio.com/ 下的每个用户都有订阅。根节点本身没有订阅。您不能跳过查询中的级别。如果要显示所有用户的所有订阅列表，则需要在数据库中有一个所有订阅列表。
然后我需要创建另一个名为 all-subscriptions 的密钥并将所有程序添加到该 Ir 中，无论用户如何。这样我就可以填充所有程序，还是他们有任何其他方式来实现它？

标签： android firebase

【解决方案1】：

我不确定您的 mRef 变量指的是什么，但这就是我所需要的：

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    RecyclerView view = new RecyclerView(this);
    setContentView(view);

    view.setLayoutManager(new LinearLayoutManager(this));

    Firebase.setAndroidContext(this);
    Firebase ref = new Firebase("https://stackoverflow.firebaseio.com/36299197").child("subscriptions/obama@gmsil,com");

    FirebaseRecyclerAdapter<Program, ProgramVH> adapter = new FirebaseRecyclerAdapter<Program, ProgramVH>(Program.class, android.R.layout.two_line_list_item, ProgramVH.class, ref) {
        @Override
        public void populateViewHolder(final ProgramVH programViewHolder, Program program, int position) {
            System.out.println("populateViewHolder for position "+position+" with program "+program);
            programViewHolder.title.setText(program.getTitle());
            programViewHolder.level.setText(""+program.getLength()); // coerce to string to prevent android.content.res.Resources$NotFoundException
        }
    };
    view.setAdapter(adapter);
}

由于我使用的是 stock 布局，所以我将视图持有者修改为：

public static class ProgramVH extends RecyclerView.ViewHolder {
    protected TextView title;
    protected TextView level;

    public ProgramVH(View view) {
        super(view);
        this.title = (TextView) view.findViewById(android.R.id.text1);
        this.level = (TextView) view.findViewById(android.R.id.text2);
    }
}

我为此添加了一个Activity36299197 到我的sample repo。如果您启动应用并从初始列表中选择 Activity36299197，您将看到来自您发布的 JSON 的数据。

【讨论】：

我用mRef 变量做了一些调试并更新了问题！
如果您立即将完整信息添加到问题中，这将非常有帮助。我不能一直回到它并扫描更新。