Issue
Activity code. After entering the Activity, I get an error that:
Can't convert an object of type java.lang.String to type com.test.nmfestdemo.Info
I tried to write differently, but then either nothing happened at all, or there was an error with null.
public class Account extends AppCompatActivity {
private Button button1;
private TextView textview1;
private Intent i =new Intent();
private String User_KEY ="User";
private DatabaseReference mDataBase;
private FirebaseAuth mAuth;
private DatabaseReference mDataBaseInfo;
private String Info_KEY ="Info";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_account);
button1 = findViewById(R.id.button1);
textview1 = (TextView) findViewById(R.id.textview1);
mDataBase = FirebaseDatabase.getInstance().getReference(User_KEY);
mDataBaseInfo = FirebaseDatabase.getInstance().getReference(Info_KEY);
getDataFromDB();
button1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
mAuth.signOut();
i.setClass(getApplicationContext(),MainActivity.class);
startActivity(i);
}
});
}
public void getDataFromDB(){
ValueEventListener vListener = new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot postSnapshot) {
for (DataSnapshot ds : postSnapshot.getChildren()) {
Info info = ds.getValue(Info.class);
textview1.setText(String.valueOf(info));
}
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
}
};
mDataBaseInfo.addValueEventListener(vListener);
}
}
Class code
public class Info {
public String day;
public Info(String day) {
this.day = day;
}
public String getDay() {
return day;
}
}
Error code and FireBase structure
Solution
If Info_KEY variable contains a String which value that is equal to "Info", then that expected behavior, to get the following error:
Can't convert object of type java.lang.String to type com.test.nmfestdemo.Info
And this is because, under the "Info" node, there are no Info objects. There is only a single field called day, which contains the String value of "1". So there is no way you can convert a String object into an object of type Info. If you want to read the value of day field, then you should remove the loop:
public void getDataFromDB(){
ValueEventListener vListener = new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot postSnapshot) {
Info info = postSnapshot.getValue(Info.class);
textview1.setText(info.getDay());
}
@Override
public void onCancelled(@NonNull DatabaseError error) {
Log.d("TAG", error.getMessage()); //Never ignore potential errors!
}
};
mDataBaseInfo.addValueEventListener(vListener);
}
Answered By - Alex Mamo
Answer Checked By - David Marino (JavaFixing Volunteer)
