无法按动按钮才能正常工作 [英] Can't get button press to work in flutter

问题描述

好吧，我是扑扑/飞镖的新手，所以对我轻松一点。我只是在尝试制作一个非常简单的应用，在该应用中，当您按下按钮时，会有一些文本更新告诉您按下按钮的次数。我不知道为什么这段代码不起作用。出现该按钮，但按此按钮无任何反应。

Ok I'm pretty new to flutter/ dart so go easy on me. I'm just trying to make a very simple app where when you press a button some text updates telling you how many times you have pressed the button. I have no idea why this code doesn't work. The button appears but nothing happens when you press it.

import 'package:flutter/material.dart';

class Homepage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Column(
      children: <Widget>[],
    );
  }
}

class Buttonz extends StatefulWidget {
  @override
  _ButtonBeingPressed createState() => new _ButtonBeingPressed();
}

class _ButtonBeingPressed extends State<Buttonz> {
  int _timesPressed = 0;
  _buttonWasPressed() {
    setState(() {
      _timesPressed++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return new Column(children: <Widget>[
     new Center(
          child: new Row(
        children: <Widget>[
          new Text(
              'The button was pressed ' + _timesPressed.toString() + "         
 times"),
          new RaisedButton(
            onPressed: _buttonWasPressed(),
           child: new Row(
              children: <Widget>[new Text("Press meh")],
            ),
          ),
        ],
      ))
    ]);
  }
}

推荐答案

您的问题是您没有将回调传递给 RaisedButton ，而是调用了回调。

Your problem is that you didn't pass a callback to RaisedButton, you invoked your callback.

new RaisedButton(
  onPressed: _buttonWasPressed(), // invokes function
  child: new Row(children: <Widget>[new Text("Press meh")]),
);

要将回调传递给另一个小部件，您有两种选择：

To pass a callback to another widget you have two choices:

 new RaisedButton(
   onPressed: _buttonWasPressed, // no `()`,
   child: ...
 )

通过闭包

Pass a closure

 new RaisedButton(
   onPressed: () {
     // do something.
   },
   ..
 )

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