【发布时间】：2017-09-02 15:52:34
【问题描述】：
我已经搜索了 FirebaseRecyclerAdapter 和相关类的文档，但找不到一种方法来做我想做的事（不自己重建库）。
我正在开发一个内置消息传递功能的应用程序（包括群组和直接向其他用户发送消息）。
群聊有效，因为它从群聊节点下的数据库引用中提取每条消息。
直接消息很棘手。我想跳过参考中不包含当前用户的模型 ID 的节点，以及他们尝试发送消息的用户（这样他们就看不到其他人的消息）。
在下面的代码中，如果 viewType = 10，我会尝试返回 null，因为我不希望显示聊天气泡...正如您所期望的那样，我从 RecyclerViewAdapter 类中得到一个空指针异常。
我知道为什么我会收到错误消息。我故意将 null 传递给它，以尝试跳过（或迭代当前项目），而不在任何位置显示聊天气泡。
这是我的 firebase 结构（导出的 JSON）：Database Structure
这是一个堆栈跟踪供参考：
FATAL EXCEPTION: main
Process: com.aztechdev.squad, PID: 21249
java.lang.NullPointerException: Attempt to write to field 'int android.support.v7.widget.RecyclerView$ViewHolder.mItemViewType' on a null object reference
at android.support.v7.widget.RecyclerView$Adapter.createViewHolder(RecyclerView.java:6368)
at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:5555)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5440)
at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5436)
at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2224)
at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1551)
at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1511)
at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:570)
at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3583)
at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3312)
at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3844)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at com.mxn.soul.flowingdrawer_core.FlowingDrawer.onLayout(FlowingDrawer.java:138)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1795)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.support.constraint.ConstraintLayout.onLayout(ConstraintLayout.java:1197)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.support.design.widget.HeaderScrollingViewBehavior.layoutChild(HeaderScrollingViewBehavior.java:131)
at android.support.design.widget.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:42)
at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1391)
at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:870)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.support.v4.widget.DrawerLayout.onLayout(DrawerLayout.java:1193)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
09-02 10:47:22.899 21249-21249/com.aztechdev.squad E/AndroidRuntime: at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1741)
at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1585)
at android.widget.LinearLayout.onLayout(LinearLayout.java:1494)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
at com.android.internal.policy.DecorView.onLayout(DecorView.java:726)
at android.view.View.layout(View.java:17637)
at android.view.ViewGroup.layout(ViewGroup.java:5575)
at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2346)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2068)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1254)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6337)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:874)
at android.view.Choreographer.doCallbacks(Choreographer.java:686)
at android.view.Choreographer.doFrame(Choreographer.java:621)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:860)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
这是我的 FirebaseRecyclerAdapter：
package com.aztechdev.squad.adapter;
import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.text.format.DateUtils;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import com.aztechdev.squad.helpers.common;
import com.aztechdev.squad.model.DirectChatModel;
import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.google.firebase.database.DatabaseReference;
import hani.momanii.supernova_emoji_library.Helper.EmojiconTextView;
import com.aztechdev.squad.R;
public class DirectFirebaseAdapter extends FirebaseRecyclerAdapter<DirectChatModel,DirectFirebaseAdapter.MyChatViewHolder> {
private static final int RIGHT_MSG = 0;
private static final int LEFT_MSG = 1;
private static final int RIGHT_MSG_IMG = 2;
private static final int LEFT_MSG_IMG = 3;
public static final String TAG = "DirectFirebaseAdapter";
private ClickListenerChatFirebase mClickListenerChatFirebase;
private String mUID;
private Context mContext;
public DirectFirebaseAdapter(Context context, DatabaseReference ref, String mUID, ClickListenerChatFirebase mClickListenerChatFirebase) {
super(DirectChatModel.class, R.layout.item_message_left, DirectFirebaseAdapter.MyChatViewHolder.class, ref);
this.mUID = mUID;
this.mClickListenerChatFirebase = mClickListenerChatFirebase;
this.mContext = context;
}
@Override
public MyChatViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view;
if (viewType == RIGHT_MSG){
view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_message_right,parent,false);
return new MyChatViewHolder(view);
}else if (viewType == LEFT_MSG){
view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_message_left,parent,false);
return new MyChatViewHolder(view);
}else if (viewType == RIGHT_MSG_IMG){
view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_message_right_img,parent,false);
return new MyChatViewHolder(view);
} else if (viewType == 10) {
return null;
} else {
view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_message_left_img,parent,false);
return new MyChatViewHolder(view);
}
}
@Override
public int getItemViewType(int position) {
DirectChatModel model = getItem(position);
Log.d(TAG, "getItemCount: " + getItemCount());
Log.d(TAG, "From UID: " + model.getFrom().getId());
Log.d(TAG, "To UID: " + model.getTo().getId());
**if (!model.getFrom().getId().equals(mUID) && !model.getTo().getId().equals(mUID)) {
Log.d(TAG, "getItemViewType: UID not found");
return 10;
}**
if (model.getMapModel() != null){
if (model.getFrom().getId().equals(mUID)){
return RIGHT_MSG_IMG;
}else{
return LEFT_MSG_IMG;
}
}else if (model.getFile() != null){
if (model.getFile().getType().equals("img") && model.getFrom().getId().equals(mUID)){
return RIGHT_MSG_IMG;
}else{
return LEFT_MSG_IMG;
}
}else if (model.getFrom().getId().equals(mUID)){
return RIGHT_MSG;
}else {
return LEFT_MSG;
}
}
@Override
protected void populateViewHolder(MyChatViewHolder viewHolder, DirectChatModel model, int position) {
if (model.getTo().getId().equals(mUID)) {
viewHolder.setIvUser(model.getTo().getPhoto_profile());
viewHolder.setTvTimestamp(model.getTimeStamp(), model.getTo().getName());
} else {
viewHolder.setIvUser(model.getFrom().getPhoto_profile());
viewHolder.setTvTimestamp(model.getTimeStamp(), model.getFrom().getName());
}
viewHolder.setTxtMessage(model.getMessage());
viewHolder.tvIsLocation(View.GONE);
if (model.getFile() != null){
viewHolder.tvIsLocation(View.GONE);
viewHolder.setIvChatPhoto(model.getFile().getUrl_file());
}else if(model.getMapModel() != null){
viewHolder.setIvChatPhoto(common.local(model.getMapModel().getLatitude(),model.getMapModel().getLongitude()));
viewHolder.tvIsLocation(View.VISIBLE);
}
}
public class MyChatViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
TextView tvTimestamp,tvLocation;
EmojiconTextView txtMessage;
ImageView ivUser,ivChatPhoto;
public MyChatViewHolder(View itemView) {
super(itemView);
tvTimestamp = (TextView)itemView.findViewById(R.id.timestamp);
txtMessage = (EmojiconTextView)itemView.findViewById(R.id.txtMessage);
tvLocation = (TextView)itemView.findViewById(R.id.tvLocation);
ivChatPhoto = (ImageView)itemView.findViewById(R.id.img_chat);
ivUser = (ImageView)itemView.findViewById(R.id.ivUserChat);
}
@Override
public void onClick(View view) {
int position = getAdapterPosition();
DirectChatModel model = getItem(position);
if (model.getMapModel() != null){
mClickListenerChatFirebase.clickImageMapChat(view,position,model.getMapModel().getLatitude(),model.getMapModel().getLongitude());
}else{
// mClickListenerChatFirebase.clickImageChat(view,position,model.getUserModel().getName(),model.getUserModel().getPhoto_profile(),model.getFile().getUrl_file());
}
}
public void setTxtMessage(String message){
if (txtMessage == null)return;
txtMessage.setText(message);
}
public void setIvUser(String urlPhotoUser){
if (ivUser == null)return;
CircleTransform circleTransform = new CircleTransform();
GlideApp.with(ivUser.getContext()).load(urlPhotoUser).centerCrop().transform(circleTransform).override(160,160).into(ivUser);
}
public void setTvTimestamp(String timestamp, String sender){
if (tvTimestamp == null)return;
tvTimestamp.setText(sender + " - " + convertTimestamp(timestamp));
}
public void setIvChatPhoto(String url){
if (ivChatPhoto == null)return;
GlideApp.with(ivChatPhoto.getContext()).load(url)
.override(200, 200)
.fitCenter()
.into(ivChatPhoto);
ivChatPhoto.setOnClickListener(this);
}
public void tvIsLocation(int visible){
if (tvLocation == null)return;
tvLocation.setVisibility(visible);
}
}
private CharSequence convertTimestamp(String millis){
return DateUtils.getRelativeTimeSpanString(Long.parseLong(millis), System.currentTimeMillis(), DateUtils.SECOND_IN_MILLIS);
}
}
【问题讨论】：
标签： android firebase firebase-realtime-database android-recyclerview