Question

我不想一直重复这段代码：

Button btnClicks = FindViewById<Button>(Resource.Id.MyButton);
Button btnWarning = FindViewById<Button>(Resource.Id.ButtonWarning);

如何改进此代码以使其看起来更干净？这个代码垃圾邮件真的会影响应用程序的性能吗？

 protected override void OnResume()
    {          
        base.OnResume();
        Button btnClicks = FindViewById<Button>(Resource.Id.MyButton);
        Button btnWarning = FindViewById<Button>(Resource.Id.ButtonWarning);

        btnWarning.Click += btnWarn;
    }

    protected override void OnPause()
    {
        base.OnPause();
        Button btnClicks = FindViewById<Button>(Resource.Id.MyButton);
        Button btnWarning = FindViewById<Button>(Resource.Id.ButtonWarning);

        btnWarning.Click -= btnWarn;

    }

    private void btnWarn(object sender, EventArgs e)
    {
        Button btnWarning = FindViewById<Button>(Resource.Id.ButtonWarning);
        btnWarning.Text = string.Format("Warning Test");
    }

Answer 1

使按钮类变量，然后在OnCreate：

Button btnClicks;
Button btnWarning; 

protected override void OnCreate(Bundle bundle)
{
   base.OnCreate(bundle);
   btnClicks = FindViewById<Button>(Resource.Id.MyButton);
   btnWarning = FindViewById<Button>(Resource.Id.ButtonWarning); 
   btnWarning.Click += btnWarn;
}

现在，

private void btnWarn(object sender, EventArgs e)
{
   btnWarning.Text = string.Format("Warning Test");
}

Answer 2

你真的需要在暂停时删除Click处理程序吗？

通常在OnCreate中初始化处理程序就足够了。

如果您确实需要多次访问视图，请在Activity类本身中保留对视图的引用：

class MyActivity : Activity
{
  Button myButton;

  protected override void OnCreate(Bundle bundle)
  {
     base.OnCreate(bundle);
     var myButton = FindViewById<Button>(Resource.Id.MyButton);
  }

  protected override void OnPause()
  {
    // do something with myButton
  }
}

Answer 3

每当您订阅某个活动时，您都应该取消订阅以释放附加到该活动的所有内存资源。如果您不取消订阅，最终可能会获得OutOfMemoryException。实际上，你正确地做了那个部分，但正如其他人提到的，你需要使用OnCreate来查找一次视图：

Button btnClicks;
Button btnWarning; 

protected override void OnCreate(Bundle bundle)
{
   base.OnCreate(bundle);

   btnClicks = FindViewById<Button>(Resource.Id.MyButton);
   btnWarning = FindViewById<Button>(Resource.Id.ButtonWarning); 
}

protected override void OnResume()
{          
    base.OnResume();

    btnWarning.Click += btnWarn;
}

protected override void OnPause()
{
    base.OnPause();

    btnWarning.Click -= btnWarn;
}

怎么做而不重复代码？ Xamarin - Android

3 个答案: