相关疑难解决方法(0)

我想在按下图标后更改它的颜色，但似乎以下代码不起作用。

  void actionClickRow(String key) {
    Navigator.of(context).push(
      new MaterialPageRoute(builder: (context) {
        return new Scaffold(
            appBar: new AppBar(
              title: new Text(key),
              actions: <Widget>[
                new IconButton(
                  icon: new Icon(
                    Icons.favorite, 
                    color: isSaved(key)  ? Colors.red : null,  //<--- if key is already saved, then set it to red
                    ), 
                  onPressed: ()
                  {
                    setState(() //<--whenever icon is pressed, force redraw the widget
                    {
                      pressFavorite(key);
                    });                    
                  }
                ),
              ],
            ),
            backgroundColor: Colors.teal,
            body: _showContent(key));
      }),
    );
  }


 void pressFavorite(String key)
  {
    if (isSaved(key))
      saved_.remove(key);
    else
      saved_.add(key); …