if（url！= null）不起作用

Question

因为如果“url”有信息，我可以有所作为。因为我做得不好而创造。它不起作用

        Bundle bundle = getIntent().getExtras();
    String url = bundle.getString("url");

    if (url != null) {
        emVideoView = (EMVideoView)findViewById(R.id.video_play_activity_video_view);
        emVideoView.setOnPreparedListener(this);
        //For now we just picked an arbitrary item to play.  More can be found at
        //https://archive.org/details/more_animation
        emVideoView.setVideoURI(Uri.parse(url));
    } else{
        Toast.makeText(getBaseContext(), "Not url found!", Toast.LENGTH_SHORT).show();
        MainActivity.this.finish();
    }

Answer 1

尝试：

if (!String.IsNullOrEmpty(url)) 

这将确保String.Empty值也不存在，这与字符串为null不同。换句话说：

String s = null;

与：

不同

String s = String.Empty;

Answer 2

if(url != null)
  if(!url.isEmpty())

此外，当从捆绑中检索项目时，简单的if(bundle.getString("url") != null)也会有所帮助。