Question 128188 in Android Studio Question posted in
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Android Studio – I wanna limit value of a quantity that user put on the text field (Flutter)

I want a user can input no more than 100 in my textfield.
If a user put more than 100 –let’s say 123–, the text will show 100 instead of 123.

here is my code

TextField(
                                  controller: qtyController,
                                  keyboardType: TextInputType.number,
                                  onTap: () => qtyController.text = '',
                                  inputFormatters: [FilteringTextInputFormatter. digitsOnly,
                                    LengthLimitingTextInputFormatter(3),
                                  ],
                                  textAlign: TextAlign.center,
                                  style: TextStyle(color: Colors.white),
                                )
Tags:

3

Answers


  1. 0

    You can use the onChanged callback to listen to the changes

        TextField(
      controller: qtyController,
      keyboardType: TextInputType.number,
      onTap: () => qtyController.text = '',
      onChanged: (val){
       if (val.isNotEmpty) {
        if(int.parse(val)>=100) {
          qtyController.text = "100";
        }
       }
      },
      inputFormatters: [
        FilteringTextInputFormatter.digitsOnly,
        LengthLimitingTextInputFormatter(3),
      ],
      textAlign: TextAlign.center,
      style: TextStyle(color: Colors.white),
    )
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  2. 0

    You can use the maxLength property to set the maximum characters allowed in the TextField. Read more about it here.

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  3. 0

    The simplest approach is to supply an onChanged() callback to a TextField or a TextFormField. Whenever the text changes, the callback is invoked.

    A more powerful, but more elaborate approach, is to supply a TextEditingController as the controller property of the TextField or a TextFormField.

    Details on here:https://docs.flutter.dev/cookbook/forms/text-field-changes

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