Enable/ disable a raisebutton according to the textform field in flutter

Question

I want to enable a button when the textformfield is not empty and disable a button when the textformfield is empty.

bool isEnabled = false;
  TextEditingController _textEditingController = TextEditingController();
RaisedButton(
                // disabledColor: Colors.grey,
                child: Text("Click"),
                onPressed: () {
                  setState(() {
                    if (_textEditingController.text.isNotEmpty) {
                      isEnabled = true;
                    } else
                      isEnabled = false;
                  });
                })

Answer 1

Right now, what you are doing is wrong, because you can not enable a disabled button using onPressed.

It should be done like, Inside TextFormField, set value of isEnabled to true is input text length is greater than zero, false otherwise.

        TextFormField(
            onChanged: (text) {
                setState(() {
                  if(text.length>0)
                     isEnabled=ture;
                  else
                     isEnabled=false;
                  });
            }

and then disable/enable button like this,

onPressed: isEnabled?
    (){
     //do something
   } 
: null;// or pass blank (){}