Use the Calculation Inside the App

Import the Calculation into the main source code by adding, at the top of main.dart, the following:

​ ​import​ ​"calculator.dart"​;

You need to define a Calculation object for the _CalculatorHomePageState so, below:

layout/calculator/lib/main.dart
​ ​String​ _str = ​"0"​;

You need to add:

layout/calculator/lib/main.dart
​ ​var​ _calculation = Calculation();

You will also need to properly implement the _CalculatorHomePageState’s add, deleteOne, and deleteAll methods, which will have to be calls to setState and the Calculation methods, like this:

layout/calculator/lib/main.dart
​ ​void​ ​add​(​String​ a) {
​  setState((){
​  _calculation.add(a);
​  _str = _calculation.getString();
​  });
​ }
​ 
​ ​void​ ​deleteAll​() {
​  setState(() {
​  _calculation.deleteAll();
​  _str = _calculation.getString();
​  });
​ }
​ 
​ ​void​ ​deleteOne​() {
​  setState(() {
​  _calculation.deleteOne();
​  _str = _calculation.getString();
​  });
​ }
​ 
​ ​void​ ​getResult​() {
​  setState(() {
​  _str = _calculation.getResult().toString();
​  });
​  _calculation = ​new​ Calculation();
​ }
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