I'm new to Android and Firebase environment but I'm working on it !
I'm working on an Android app and I need to read some values related to a child within a Firebase database. After this initial read, I need to modify / update these values and write them to the same child.
public class MainActivity extends Activity {
public static class Shoe extends JSONObject {
private String name;
private int size;
Shoe(){
// Default constructor required for calls to
// DataSnapshot.getValue(Shoe.class)
}
Shoe( String nm, int sz) { this.name = nm; this.size = sz; }
public int getSize() { return this.size; }
public void setSize(int sz) { this.size = sz; }
public String getName() { return this.name;}
public void setName(String nm) {this.name = nm; }
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.d(TAG, "onCreate");
// Write a message to the database
FirebaseDatabase database = FirebaseDatabase.getInstance();
database.setPersistenceEnabled(true);
DatabaseReference myRefTarget = database.getReference("target");
Shoe obj1 = new Shoe("item ID 1", 99);
Shoe obj2 = new Shoe("item ID 2", 1000);
final Shoe obj_old = new Shoe();
Shoe obj_new = new Shoe();
DatabaseReference myRefDeviceA = myRefTarget.child("deviceA").getRef();
myRefDeviceA.keepSynced(true);
myRefDeviceA.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot)
{
obj_old.setName( dataSnapshot.getValue(Shoe.class).getName());
obj_old.setSize( dataSnapshot.getValue(Shoe.class).getSize());
Log.d(TAG_CLOUD, "from onDataChange: deviceA = " + obj_old.getName() + ", " + obj_old.getSize());
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
// HERE
Log.d(TAG_CLOUD, "Name = " + obj_old.getName() + ", Size = " + obj_old.getSize());
}
the issue I got is that the read operation is asynchronously done..
D/FROM CLOUD: Name = null, Size = 0
D/FROM CLOUD: from onDataChange: deviceA = item ID 1, 99
how can adapt / modify the source code in such way that first "read" to give me values different than null and '0' ? "HERE" line eg.
Name = item ID 1 Size = 99
Thank you.
