weird problem:
This code:
xNames[index] = String.valueOf(currentAttendance.getXName());
OUTPUT: "null"
but this code works fine:
xValues[index] = currentAttendance.getxValues();
OUTPUT: 7
any help thank you guys,,,, thank you , I LOVE YOU
this is my snippet code:
ref.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
int count = (int) dataSnapshot.getChildrenCount();
int[] xValues = new int[count];
int[] yValues = new int[count];
String[] xNames = new String[count];
int index = 0;
for (DataSnapshot myDatabases : dataSnapshot.getChildren()) {
CurrentAttendance cA = myDatabases.getValue(CurrentAttendance.class);
if (cA != null) {
xNames[index] = String.valueOf(cA.getXName());
xValues[index] = cA.getUserCount();
}
if (cA != null) {
yValues[index] = cA.getCurrentAttendance();
}
index++
}
}
}
Database structure:
To solve this, please use the following lines of code:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = rootRef.child("Attendance").child(uid);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String xname = dataSnapshot.child("xname").getValue(String.class);
Log.d(TAG, xname);
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
}
};
uidRef.addListenerForSingleValueEvent(valueEventListener);
The output in your logcat will be:
Vaianaa
To get all the user names, please use the following lines of code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference attendanceRef = rootRef.child("Attendance");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String xname = ds.child("xname").getValue(String.class);
Log.d(TAG, xname);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
}
};
attendanceRef.addListenerForSingleValueEvent(valueEventListener);
The output will be:
Vaianaa
Newton
Related
I want to read some specific child from the parent-child, by getchild() function but this will not work properly.
FirebaseUser FUser = mAuth.getCurrentUser();
String userid = FUser.getUid();
DatabaseReference DR;
DR = FirebaseDatabase.getInstance().getReference().child("HistoryTable").child(userid);
DR.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
// Iterable<DataSnapshot> root = dataSnapshot.getChildren();
// Toast.makeText(getApplicationContext(), "ds "+dataSnapshot.getChildren(),Toast.LENGTH_LONG).show();
for (DataSnapshot ds: dataSnapshot.getChildren()) {
// Toast.makeText(getApplicationContext(), "ds "+ds,Toast.LENGTH_LONG).show();
for (DataSnapshot d: ds.getChildren()) {
String Height = d.getKey() + d.getValue() + "\n".toString();
String ch = d.child("1Height:").getValue(String.class);
// tv.append(Height);
tv.append(ch);
}
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
I want to get this four child from every key.
you have to add your push id in reference :-
DR = FirebaseDatabase.getInstance().getReference().child("HistoryTable").child(userid).child("push id");
DR.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
// Iterable<DataSnapshot> root = dataSnapshot.getChildren();
// Toast.makeText(getApplicationContext(), "ds "+dataSnapshot.getChildren(),Toast.LENGTH_LONG).show();
for (DataSnapshot ds: dataSnapshot.getChildren()) {
// Toast.makeText(getApplicationContext(), "ds "+ds,Toast.LENGTH_LONG).show();
for (DataSnapshot d: ds.getChildren()) {
String Height = d.getKey() + d.getValue() + "\n".toString();
String ch = d.child("1Height:").getValue(String.class);
// tv.append(Height);
tv.append(ch);
}
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
Try like this if you just want to read the value. if you want to read data only once use addListenerForSingleValueEvent()
*Try to read values by object stucture https://firebase.google.com/docs/database/android/read-and-write#basic_write
DR.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(#NonNull DataSnapshot dataSnapshot) {
for (DataSnapshot d: ds.getChildren()) {
//below line may cause null pointer Exception
String Height = d.getKey() + d.getValue() + "\n".toString();
if(d.child("1Height:").getValue()!=null){
String ch = d.child("1Height:").getValue(String.class);
//tv.append(Height);
tv.append(ch);}
}
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
}
});
To get the value of your 4UserId property, simply use the following lines of code:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = rootRef.child("HistoryTable").child(uid);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String userId = ds.child("4UserId").getValue(String.class);
Log.d(TAG, userId);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!
}
};
uidRef.addListenerForSingleValueEvent(valueEventListener);
The result in your logcat will be:
2Wwrjx...P2obFO83
I have the following database. What I need is to get the total count of comments per post when posting UID equal to current_user_uid.
Any suggestion on how to do this?
To solve this, please use the following code:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
Query query = rootRef.child("Posts").orderByChild("uid").equalTo(current_user_uid);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
long count = ds.child("comments").getChildrenCount();
Log.d("TAG", "Count: " + count);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {
Log.d(TAG, databaseError.getMessage());
}
};
query.addListenerForSingleValueEvent(valueEventListener);
I did't want to make it key and value , I have tried a lot to find a solution, but I can't
And this my code when I tried to get it by key and value
mFriendID = (DatabaseReference) FirebaseDatabase.getInstance().getReference().child("friends").child(current_user).addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
fri_id = dataSnapshot.child("fri_id").getValue().toString();
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
To get the highlighted key, please use the following code:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference uidRef = rootRef.child("friends").child(uid);
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String key = ds.getKey();
Log.d("TAG", key);
}
}
#Override
public void onCancelled(#NonNull DatabaseError databaseError) {}
};
uidRef.addListenerForSingleValueEvent(valueEventListener);
This is my Firebase realtime database structure:
How to get these data in a List to pass the data to the Model Class.
When I tried by generation data like below and it works.
listCourse = new ArrayList<>();
listCourse.add(new CourseModel("UserID", "CourseCode", "CourseName"));
listCourse.add(new CourseModel("122345", "TMN1234","System Programming"));
I just want get the data from firebase in this format..
You can retrieve list by this method.
Firebase ref = new Firebase(FIREBASE_URL);
ref.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot snapshot) {
Log.i("Count " ,""+snapshot.getChildrenCount());
for (DataSnapshot postSnapshot: snapshot.getChildren()) {
CourseModel course = postSnapshot.getValue(CourseModel.class);
}
}
#Override
public void onCancelled(FirebaseError firebaseError) {
Log.e("The read failed: " ,firebaseError.getMessage());
}
});
Please refer this documentation: https://firebase.google.com/docs/database/android/lists-of-data
if (dataSnapshot.exists()) {
int i = 1;
for (DataSnapshot dataSnapshot1 : dataSnapshot.child(userID).child("Course").getChildren()) {
coursecode[i]= dataSnapshot1.getKey();
coursename[i]=dataSnapshot.child(userID).child("Course").child(coursecode[i]).child("CourseName").getValue(String.class);
listCourse.add(new CourseModel(userID,coursecode[i],coursename[i]));
i++;
}
}
I figured it out.. this is working for me..
To Access Child you can to create reference.!
DatabaseReference userRef= FirebaseDatabase.getInstance().getReference("users");
DatabaseReference userChildRef= userRef.child(childId);
DatabaseReference userCourseRef= userChildRef.child("courses");
DatabaseReference userCourseIdRef= userCourseRef.child(courseId);
userCourseIdRef.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
Log.i(TAG, dataSnapshot.getValue(String.class);
}
#Override
public void onCancelled(DatabaseError databaseError) {
Log.w(TAG, "onCancelled", databaseError.toException());
}
});
Tol solve this, there are to ways. First would be to get the data as objects of CourseModel class like this:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference coursesRef = rootRef.child("Users").child(uid).child("Courses");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
List<CourseModel> list = new ArrayList<>();
for(DataSnapshot ds : dataSnapshot.getChildren()) {
CourseModel courseModel = ds.getValue(CourseModel.class);
list.add(courseModel);
}
//Do what you need to do with the list of CourseModel objects
Log.d("TAG", list.ToString);
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
coursesRef.addListenerForSingleValueEvent(valueEventListener);
The second one, would be to get the courseName as a String like this:
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference coursesRef = rootRef.child("Users").child(uid).child("Courses");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
List<String> list = new ArrayList<>();
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String courseName = ds.child("CourseName").getValue(String.class);
list.add(courseName);
}
//Do what you need to do with the list of strings
Log.d("TAG", list.ToString);
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
coursesRef.addListenerForSingleValueEvent(valueEventListener);
public void RetreiveNewQuestions(){
Random random = new Random();
int questionInt1;
questionInt1 = random.nextInt(2-1) + 1;
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
FirebaseDatabase.getInstance().getReference().child("questions").child("animal").child("1").child("question").addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String question1 = dataSnapshot.getValue(String.class);
question[0] = question1;
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
This method is supposed to read questions randomly, but first for testing purposes I tried to see if it can read one question, but did not work.
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game);
questionRef = FirebaseDatabase.getInstance().getReference("questions");
category = "animal";
RetreiveNewQuestions();
String quizData[][] = {
//Format, {Question, right answer, option1, option2, option3}
{question[0], "Log", "Tree", "Knee"," Bee"},
{ "Potato", "Rar", "Laugh", "Test","Minute"}
};
What my data looks like in Firebase
If you want to get only the first question, then please use the following code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference ref = rootRef.child("questions").child("animal").child("1");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
String question = dataSnapshot.child("questions").getValue(String.class);
Log.d("TAG", question);
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
ref.addListenerForSingleValueEvent(valueEventListener);
If you want to get all the questions, please use the following code:
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference animalRef = rootRef.child("question").child("animal");
ValueEventListener valueEventListener = new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()) {
String question = ds.child("question").getValue(String.class);
Log.d("TAG", question);
}
}
#Override
public void onCancelled(DatabaseError databaseError) {}
};
animalRef.addListenerForSingleValueEvent(valueEventListener);