Java Firebase如何从数据库中正确检索数据和显示数据
我试图从firebase中提取数据并显示用户的名称和状态。我目前遇到一个空点异常Java Firebase如何从数据库中正确检索数据和显示数据,java,android,firebase,firebase-realtime-database,Java,Android,Firebase,Firebase Realtime Database,我试图从firebase中提取数据并显示用户的名称和状态。我目前遇到一个空点异常 public class ProfileFragment extends Fragment { private DatabaseReference mUserDatabase; private FirebaseUser mCurrentUser; @Nullable @Override public View onCreateView(@NonNull LayoutInflater inflater, @Nul
public class ProfileFragment extends Fragment {
private DatabaseReference mUserDatabase;
private FirebaseUser mCurrentUser;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_profile, container, false);
CircleImageView displayProfilePicture = view.findViewById(R.id.settings_profile_picture);
final TextView mName = view.findViewById(R.id.settings_user_name);
final TextView mStatus = view.findViewById(R.id.settings_user_status);
mCurrentUser = FirebaseAuth.getInstance().getCurrentUser();
String current_uid = Objects.requireNonNull(mCurrentUser).getUid();
mUserDatabase = FirebaseDatabase.getInstance().getReference().child("Users").child(current_uid);
mUserDatabase.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
String name = (Objects.requireNonNull(dataSnapshot.child("name").getValue())).toString();
String status = Objects.requireNonNull(dataSnapshot.child("status").getValue()).toString();
String image = Objects.requireNonNull(dataSnapshot.child("image").getValue()).toString();
String thumb_image = Objects.requireNonNull(dataSnapshot.child("thumb image ").getValue()).toString();
mName.setText(name);
mStatus.setText(status);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
return view;
}}
我也尝试过用不同的方式实现这一点,但是我仍然无法显示数据
public class ProfileFragment extends Fragment {
private DatabaseReference mUserDatabase;
private FirebaseUser mCurrentUser;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_profile, container, false);
CircleImageView displayProfilePicture = view.findViewById(R.id.settings_profile_picture);
final TextView mName = view.findViewById(R.id.settings_user_name);
final TextView mStatus = view.findViewById(R.id.settings_user_status);
mCurrentUser = FirebaseAuth.getInstance().getCurrentUser();
String current_uid = Objects.requireNonNull(mCurrentUser).getUid();
mUserDatabase = FirebaseDatabase.getInstance().getReference().child("Users").child(current_uid);
mUserDatabase.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
for(DataSnapshot datas: dataSnapshot.getChildren()){
String keys=datas.getKey();
String displayname=datas.child("name").getValue().toString();
mName.setText(displayname);
}}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
return view;
}}
我的数据库结构如下:
由于您已经拥有
用户ID
,因此不需要循环即可访问直接子项
请尝试以下操作:
mUserDatabase = FirebaseDatabase.getInstance().getReference().child("Users").child(current_uid);
mUserDatabase.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
String keys=dataSnapshot.getKey();
String displayname=dataSnapshot.child("name").getValue().toString();
mName.setText(displayname);
}}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
将logcat张贴到您获得的代码行
NullPointerException
?请回复@。