Answers for "textfield shapes in flutter"

textfield border flutter

decoration: new InputDecoration(
                border: new OutlineInputBorder(
                    borderSide: new BorderSide(color: Colors.teal)),
                hintText: 'Tell us about yourself',
                helperText: 'Keep it short, this is just a demo.',
                labelText: 'Life story',
                prefixIcon: const Icon(
                  Icons.person,
                  color: Colors.green,
                ),
                prefixText: ' ',
                suffixText: 'USD',
                suffixStyle: const TextStyle(color: Colors.green)),
          ),

squared text field flutter

new TextFormField(
                      decoration: new InputDecoration(
                        labelText: "Enter Email",
                        fillColor: Colors.white,
                        border: new OutlineInputBorder(
                          borderRadius: new BorderRadius.circular(25.0),
                          borderSide: new BorderSide(
                          ),
                        ),
                        //fillColor: Colors.green
                      ),
                      validator: (val) {
                        if(val.length==0) {
                          return "Email cannot be empty";
                        }else{
                          return null;
                        }
                      },
                      keyboardType: TextInputType.emailAddress,
                    ),