What Is The Best Way To Check The Existence Of Every Child In One Node?

FirebaseDatabase.getInstance().getReference('Block').addListenerForSingleValueEvent(new ValueEventListener() { @Override public void onDataChange(DataSnapshot dataSnapshot

Solution 1:

Just traverse to the path specified using child. You will get no data if the path doesn't exist.

FirebaseDatabase.getInstance().getReference("Block")
    .child("MyUUID")
    .child("specificUUID")
    .addValueEventListener(new ValueEventListener() {

        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            if(dataSnapshot.exists()) {
                // ... Do something
            } else {
                call_method();
            }
       // ... Other code
}

Solution 2:

Try this:

Firebaseuser user=FirebaseAuth.getInstance().getCurrentUser();
DatabaseReference ref = FirebaseDatabase.getInstance().getReference().child("Block");
ref.child(user.getUid()).addListenerForSingleValueEvent(newValueEventListener() {
@OverridepublicvoidonDataChange(DataSnapshot dataSnapshot) {
       if(dataSnapshot.exist()){
          //checks first uidif(dataSnapshot.hasChild(seconduid){
               //checks if seconduid is therefor(DataSnapshotdatas:dataSnapshot.getChildren()){
                      String blocks=datas.child("block").getValue().toString();

          }
      }

   }  

}

@OverridepublicvoidonCancelled(DatabaseError databaseError) {
  }
});

This will check the first uid if(dataSnapshot.exist()) after that it will check if that uid node has the second uid that you provide if(dataSnapshot.hasChild(seconduid){ then you will iterate and get the node block