獲取文字欄位的值

在本篇指南中，你將學習如何透過以下步驟獲取使用者輸入到文字框中的文字：

1. 建立一個 TextEditingController。
2. 將 TextEditingController 提供給 TextField。
3. 顯示文字框的當前值。

要獲取使用者輸入到文字框中的文字，請建立一個 TextEditingController 並將其提供給 TextField 或 TextFormField。

// 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.
  }
}

現在你已經擁有了一個 TextEditingController，請使用 controller 屬性將其連線到文字框。

return TextField(controller: myController);

將 TextEditingController 提供給文字框後，即可開始讀取值。使用 TextEditingController 提供的 text 屬性，即可獲取使用者在文字框中輸入的字串。

以下程式碼演示了當使用者點選懸浮操作按鈕時，顯示一個包含文字框當前值的提醒對話方塊。

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),
),

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),
      ),
    );
  }
}