Android Can'；按子级顺序筛选Firebase数据
我想显示按用户ID过滤的Firebase数据。但该应用程序崩溃，调试后在Firebase适配器上显示NullPointerException。怎么办？我在片段中实现它。我没有粘贴导入的库 这是我的密码：Android Can'；按子级顺序筛选Firebase数据,android,android-fragments,firebase,firebase-realtime-database,firebaseui,Android,Android Fragments,Firebase,Firebase Realtime Database,Firebaseui,我想显示按用户ID过滤的Firebase数据。但该应用程序崩溃，调试后在Firebase适配器上显示NullPointerException。怎么办？我在片段中实现它。我没有粘贴导入的库 这是我的密码： public class MyPosts extends Fragment{ private RecyclerView postList; private DatabaseReference mDatabase; private DatabaseReference m
public class MyPosts extends Fragment{
private RecyclerView postList;
private DatabaseReference mDatabase;
private DatabaseReference mDatabaseAppriciate;
private DatabaseReference mDatabaseDisgrace;
private LinearLayoutManager layoutManager;
private FirebaseAuth mAuth= FirebaseAuth.getInstance();
private DatabaseReference mDatabaseCurrentUser;
public Query mQueryCurrentUser=null;
//private static final String TAG = "MyActivity";
private boolean mProcessAppriciate=false;
private boolean mProcessDisgrace=false;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
super.onSaveInstanceState(savedInstanceState);
View rootView = inflater.inflate(R.layout.allposts, container, false);
mDatabase= FirebaseDatabase.getInstance().getReference().child("Posts");
mDatabaseAppriciate=FirebaseDatabase.getInstance().getReference().child("Appriciate");
mDatabaseDisgrace=FirebaseDatabase.getInstance().getReference().child("Disgrace");
mDatabase.keepSynced(true);
mDatabaseAppriciate.keepSynced(true);
mDatabaseDisgrace.keepSynced(true);
//EXPERIMENT WITH LISTVIEW STARTS
postList=(RecyclerView) rootView.findViewById(R.id.postList);
postList.setHasFixedSize(true);
layoutManager=new LinearLayoutManager(getActivity());
layoutManager.setReverseLayout(true);
postList.setHasFixedSize(true);
postList.setLayoutManager(layoutManager);
postList.getRecycledViewPool().clear();
//EXPERIMENT WITH LISTVIEW ENDS
return rootView;
}
@Override
public void onStart() {
super.onStart();
//EXP CODE STARTS
FirebaseAuth.getInstance().addAuthStateListener(new FirebaseAuth.AuthStateListener() {
@Override
public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
FirebaseUser user = firebaseAuth.getCurrentUser();
if (user != null) {
// User is signed in
mDatabaseCurrentUser=FirebaseDatabase.getInstance().getReference().child("Posts");
String currentUserId=user.getUid();
mQueryCurrentUser=mDatabaseCurrentUser.orderByChild("uid").equalTo(currentUserId);
}else{
}
}
});
//EXP CODE ENDS
FirebaseRecyclerAdapter<Posts,PostViewHolder> firebaseRecyclerAdapter= new FirebaseRecyclerAdapter<Posts,PostViewHolder>(
Posts.class,
R.layout.single_post,
PostViewHolder.class,
mQueryCurrentUser
) {
@Override
protected void populateViewHolder(final PostViewHolder viewHolder, final Posts model, final int position) {
final String post_key=getRef(position).getKey();
viewHolder.setTitle(model.getTitle());
viewHolder.setDescription(model.getDescription());
viewHolder.setProfileName(model.getProfilename());
viewHolder.setImage(getContext(),model.getImage());
viewHolder.getLayoutPosition();
viewHolder.setAppriciateButton(post_key);
viewHolder.setDisgraceButton(post_key);
//Share click code below
viewHolder.Share.setOnClickListener(new View.OnClickListener() {
CallbackManager callbackManager;
ShareDialog shareDialog;
@Override
public void onClick(View v) {
FacebookSdk.sdkInitialize(getApplicationContext());
callbackManager = CallbackManager.Factory.create();
shareDialog = new ShareDialog(MyPosts.this);
if (ShareDialog.canShow(ShareLinkContent.class)) {
ShareLinkContent content = new ShareLinkContent.Builder()
.setContentTitle(model.getTitle())
.setContentDescription(model.getDescription())
.setImageUrl(Uri.parse(model.getImage()))
.setContentUrl(Uri.parse("https://developers.facebook.com"))
.build();
shareDialog.show(content);
shareDialog.registerCallback(callbackManager, new FacebookCallback<Sharer.Result>() {
@Override
public void onSuccess(Sharer.Result result) {
}
@Override
public void onCancel() {
}
@Override
public void onError(FacebookException error) {
}
});
}
}
});
//Share click code ends above
//Appriciate button on click event below
viewHolder.Appriciate.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mProcessAppriciate=true;
mDatabaseAppriciate.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (mProcessAppriciate) {
if (dataSnapshot.child(post_key).hasChild(mAuth.getCurrentUser().getUid())) {
mDatabaseAppriciate.child(post_key).child(mAuth.getCurrentUser().getUid()).removeValue();
mProcessAppriciate = false;
}else {
mDatabaseAppriciate.child(post_key).child(mAuth.getCurrentUser().getUid()).setValue(mAuth.getCurrentUser().getDisplayName());
mProcessAppriciate = false;
}
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
});
//Appriciate button click event CODE ENDS
//Disgrace Button Click Event Code Starts
viewHolder.Disgrace.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mProcessDisgrace=true;
mDatabaseDisgrace.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (mProcessDisgrace) {
if (dataSnapshot.child(post_key).hasChild(mAuth.getCurrentUser().getUid())) {
mDatabaseDisgrace.child(post_key).child(mAuth.getCurrentUser().getUid()).removeValue();
mProcessDisgrace = false;
} else {
mDatabaseDisgrace.child(post_key).child(mAuth.getCurrentUser().getUid()).setValue(mAuth.getCurrentUser().getDisplayName());
mProcessDisgrace = false;
}
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
});
//Disgrace Button Click code Ends
}
};
postList.setAdapter(firebaseRecyclerAdapter);
//test code
firebaseRecyclerAdapter.notifyDataSetChanged();
}
public static class PostViewHolder extends RecyclerView.ViewHolder{
View mView;
Button Appriciate;
Button Disgrace;
Button Share;
DatabaseReference mDatabaseAppriciate;
DatabaseReference mDatabaseDisgrace;
FirebaseAuth mAuth;
public PostViewHolder(View itemView) {
super(itemView);
mView=itemView;
Appriciate=(Button) mView.findViewById(R.id.appriciate);
Disgrace=(Button) mView.findViewById(R.id.disgraceful);
Share=(Button) mView.findViewById(R.id.share);
mDatabaseAppriciate=FirebaseDatabase.getInstance().getReference().child("Appriciate");
mDatabaseDisgrace=FirebaseDatabase.getInstance().getReference().child("Disgrace");
mAuth=FirebaseAuth.getInstance();
mDatabaseAppriciate.keepSynced(true);
mDatabaseDisgrace.keepSynced(true);
}
public void setAppriciateButton(final String post_key){
mDatabaseAppriciate.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if(dataSnapshot.child(post_key).hasChild(mAuth.getCurrentUser().getUid())){
Appriciate.setBackgroundColor(Color.GRAY);
Appriciate.setText("Appriciated");
}else{
Appriciate.setBackgroundColor(Color.GREEN);
Appriciate.setText("APPRICIATE");
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
//SET DISGRACE BUTTON CODE BELOW
public void setDisgraceButton(final String post_key){
mDatabaseDisgrace.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if(dataSnapshot.child(post_key).hasChild(mAuth.getCurrentUser().getUid())){
Disgrace.setBackgroundColor(Color.GRAY);
Disgrace.setText("Disgraced");
}else{
Disgrace.setBackgroundColor(Color.RED);
Disgrace.setText("DISGRACE");
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
//SET DISGRACE BUTTON CODE ENDS
//Setting the title to the AllActivity
public void setTitle(String title){
TextView postTitle=(TextView) mView.findViewById(R.id.allPostTitle);
postTitle.setText(title);
}
public void setDescription(String description){
TextView postDescription=(TextView) mView.findViewById(R.id.allPostDescription);
postDescription.setText(description);
}
//PROFILE NAME EXPERIMENT
public void setProfileName(String profilename){
TextView postName=(TextView) mView.findViewById(R.id.profileName);
postName.setText(profilename);
}
public void setImage(final Context context, final String image) {
final ImageView postImage=(ImageView) mView.findViewById(R.id.allPostImage);
with(context).load(image).networkPolicy(NetworkPolicy.OFFLINE).into(postImage, new Callback() {
@Override
public void onSuccess() {
}
@Override
public void onError() {
Picasso.with(context).load(image).resize(500,700).into(postImage);
}
});
}
//THREADING EXPERIMENT CODE
}
}
公共类MyPosts扩展片段{
私人RecyclerView postList；
私有数据库参考数据库；
私有数据库引用mdatabaseappricate；
私有数据库引用mdatabaselume；
私人专线经理；布局经理；
私有FirebaseAuth mAuth=FirebaseAuth.getInstance（）；
私有数据库引用mDatabaseCurrentUser；
公共查询mQueryCurrentUser=null；
//私有静态最终字符串TAG=“MyActivity”；
私有布尔MPProcessAppricate=false；
私有布尔MProcess=false；
@凌驾
创建视图上的公共视图（布局、充气机、视图组容器、，
Bundle savedInstanceState）{
super.onSaveInstanceState（savedInstanceState）；
视图根视图=充气机。充气（R.layout.allpost，container，false）；
mDatabase=FirebaseDatabase.getInstance（）.getReference（）.child（“Posts”）；
mdatabaseappricate=FirebaseDatabase.getInstance（）.getReference（）.child（“appricate”）；
mdatabaseluce=FirebaseDatabase.getInstance（）.getReference（）.child（“耻辱”）；
mDatabase.keepSynced（true）；
mDatabaseAppriciate.keepSynced（true）；
mdatabase耻辱。保持同步（true）；
//开始使用LISTVIEW进行实验
postList=（RecyclerView）rootView.findviewbyd（R.id.postList）；
setHasFixedSize（true）；
layoutManager=新的LinearLayoutManager（getActivity（））；
layoutManager.setReverseLayout（true）；
setHasFixedSize（true）；
setLayoutManager（layoutManager）；
getRecycledViewPool（）.clear（）；
//使用LISTVIEW端点进行实验
返回rootView；
}
@凌驾
public void onStart（）{
super.onStart（）；
//EXP代码开始
FirebaseAuth.getInstance（）.addAuthStateListener（新的FirebaseAuth.AuthStateListener（）{
@凌驾
AuthStateChanged上的公共void（@NonNull FirebaseAuth FirebaseAuth）{
FirebaseUser=firebaseAuth.getCurrentUser（）；
如果（用户！=null）{
//用户已登录
mDatabaseCurrentUser=FirebaseDatabase.getInstance（）.getReference（）.child（“Posts”）；
字符串currentUserId=user.getUid（）；
mQueryCurrentUser=mDatabaseCurrentUser.orderByChild（“uid”）.equalTo（currentUserId）；
}否则{
}
}
});
//EXP代码结束
FirebaseRecyclerAdapter FirebaseRecyclerAdapter=新的FirebaseRecyclerAdapter(
Posts.class，
R.单柱布局图，
PostViewHolder.class，
mQueryCurrentUser
) {
@凌驾
受保护的void populateViewHolder（最终PostViewHolder、最终Posts模型、最终int位置）{
最后一个字符串post_key=getRef（位置）.getKey（）；
setTitle（model.getTitle（））；
viewHolder.setDescription（model.getDescription（））；
setProfileName（model.getProfilename（））；
setImage（getContext（），model.getImage（））；
getLayoutPosition（）；
viewHolder.SETAPPRECIATE按钮（post_键）；
viewHolder.SETU按钮（post_键）；
//分享下面的点击代码
viewHolder.Share.setOnClickListener（新视图.OnClickListener（）{
CallbackManager CallbackManager；
共享对话框共享对话框；
@凌驾
公共void onClick（视图v）{
sdkinInitialize（getApplicationContext（））；
callbackManager=callbackManager.Factory.create（）；
shareDialog=新建shareDialog（MyPosts.this）；
if（ShareDialog.canShow（ShareLinkContent.class））{
ShareLinkContent=新的ShareLinkContent.Builder（）
.setContentTitle（model.getTitle（））
.setContentDescription（model.getDescription（））
.setImageUrl（Uri.parse（model.getImage（）））
.setContentUrl（Uri.parse（“https://developers.facebook.com"))
.build（）；
显示（内容）；
registerCallback（callbackManager，newfacebookcallback（））{
@凌驾
成功时公开作废（共享结果）{
}
@凌驾
公开作废{
}
@凌驾
public void onError（facebook异常错误）{
}
});
}
}
});
//共享点击代码结束以上
//单击下面的“事件”上的“通知”按钮
viewHolder.appricate.setOnClickListener（新视图.OnClickListener（）{
@凌驾
公共void onClick（视图v）{
MPProcessAppricate=真；
mdatabaseAppricate.addValueEventListener（新的ValueEventListener（）{
@凌驾
公共void onDataChange（DataSnapshot DataSnapshot）{
如果（mProc