Setting text value based on slider value
Change your onChangeEnd method , you don't need a return value, just call to setState after your conditions:
onChangeEnd: (double value) { print('Finish value is ' + value.toString()); if (value.toString() == '0.0') { _emotionalStatus = 'Happy'; } if (value.toString() == '1.0') { _emotionalStatus = 'Optimistic'; } if (value.toString() == '2.0') { _emotionalStatus = 'Neutral'; } if (value.toString() == '3.0') { _emotionalStatus = 'Pessimistic'; } if (value.toString() == '4.0') { _emotionalStatus = 'Sad'; } setState(() { }); },