onValueChange

smartAC.addValueEventListener(new ValueEventListener() {
boolean firstTime=true;
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
// This method is called once with the initial value and again
// whenever data at this location is updated.
String value = dataSnapshot.getValue(String.class);
textView1.setText("smartAC " + value);
if(firstTime) {
if (value.equals( "ON")) {
s4.setChecked(true);                
s1.setChecked(true);
firstTime = false;
} else {
s1.setChecked(false);
firstTime = false;
    }
   }
}

@Override
public void onCancelled(DatabaseError error) {
// Failed to read value
Log.w("file", "Failed to read value.", error.toException());
}
});