[Whether] flutter dynamic control button to click

Demand is: Before you add information to determine textfiled there is no input information, otherwise the button is grayed out and can not be clicked.

Listener : textfiled which set the onchange attribute, and refresh setstate

TextField(
                      onChanged: (value) {
                        setState(() {
                          this.phone = value;
                          if (value.length >= 11)
                            this.phoneEnough = true;
                          else
                            this.phoneEnough = false;
                        });
                      },

Whether control buttons can click on : When the method onpressed button to null when you can not click, and then modify disabledcolor property, you can control the color.
Write a small case.

MaterialButton(
                  height: 50,
                  minWidth: double.infinity,
                  color: Color(0xff0096ff),
                  disabledColor: HitchColor.gray_999999,
                  onPressed: this._buttonClickListener(),
                  shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(6)),
                  child: Text("确认", textAlign: TextAlign.center, style: TextStyle(color: Colors.white, fontSize: 16)),
                )


//点击事件，不能点击则返回null
  _buttonClickListener() {
  	if(this.canBeClicked){
  		return (){//业务代码}
  	}else{
  		return null;
  	}
  }