目錄
description bug_report

獲取文字框的輸入值

目錄

這個章節講解的是如何獲取文字框的輸入值。

  1. 建立一個 TextEditingController

  2. 把 TextEditingController 應用到 TextField 上

  3. 展示文字框當前值

1. 建立 TextEditingController

為了獲取文字框輸入值，需要建立一個 TextEditingController。在後續步驟中，這個 TextEditingController 將會被應用到 TextField 上。

TextEditingController 被應用於 TextField 或者 TextFormField 後，就可以使用它來獲取文字框輸入值。

// Define a custom Form widget.
class MyCustomForm extends StatefulWidget {
  const MyCustomForm({super.key});

  @override
  State<MyCustomForm> createState() => _MyCustomFormState();
}

// Define a corresponding State class.
// This class holds the data related to the Form.
class _MyCustomFormState extends State<MyCustomForm> {
  // Create a text controller and use it to retrieve the current value
  // of the TextField.
  final myController = TextEditingController();

  @override
  void dispose() {
    // Clean up the controller when the widget is disposed.
    myController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    // Fill this out in the next step.
  }
}

2. 把 TextEditingController 應用到 TextField 上

建立完 TextEditingController，就可以使用 controller 屬性完成 text field 繫結。

return TextField(
  controller: myController,
);

3. 展示文字框當前值

在 TextEditingController 作用於文字框後，就可以開始取值了。透過 TextEditingController 提供的 text() 方法，就能夠獲取到文字框輸入值了。

在下面的範例中，使用者點選浮層按鈕，將會觸發彈出一個對話框，對話框獲取並顯示文字框的當前值。

FloatingActionButton(
  // When the user presses the button, show an alert dialog containing
  // the text that the user has entered into the text field.
  onPressed: () {
    showDialog(
      context: context,
      builder: (context) {
        return AlertDialog(
          // Retrieve the text that the user has entered by using the
          // TextEditingController.
          content: Text(myController.text),
        );
      },
    );
  },
  tooltip: 'Show me the value!',
  child: const Icon(Icons.text_fields),
),

互動式範例

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: 'Retrieve Text Input',
      home: MyCustomForm(),
    );
  }
}

// Define a custom Form widget.
class MyCustomForm extends StatefulWidget {
  const MyCustomForm({super.key});

  @override
  State<MyCustomForm> createState() => _MyCustomFormState();
}

// Define a corresponding State class.
// This class holds the data related to the Form.
class _MyCustomFormState extends State<MyCustomForm> {
  // Create a text controller and use it to retrieve the current value
  // of the TextField.
  final myController = TextEditingController();

  @override
  void dispose() {
    // Clean up the controller when the widget is disposed.
    myController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Retrieve Text Input'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16),
        child: TextField(
          controller: myController,
        ),
      ),
      floatingActionButton: FloatingActionButton(
        // When the user presses the button, show an alert dialog containing
        // the text that the user has entered into the text field.
        onPressed: () {
          showDialog(
            context: context,
            builder: (context) {
              return AlertDialog(
                // Retrieve the text the that user has entered by using the
                // TextEditingController.
                content: Text(myController.text),
              );
            },
          );
        },
        tooltip: 'Show me the value!',
        child: const Icon(Icons.text_fields),
      ),
    );
  }
}