Question

我刚刚开始学习Android并尝试编写一个简单的应用程序。点击按钮后，MP开始播放。

以下代码运行正常但我无法弄清楚如何显示祝酒词当媒体播放器尝试捕获语句发生异常时。

我想将播放器线程保持在单独的类中以进行进一步的实验。

public class MainActivity extends Activity {
static String url="http://stream001.radio.hu:8080/mr3.mp3";
static Activity context;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
        context=this;
        //set button listener
        Button btn=(Button) findViewById(R.id.button1);
        btn.setOnClickListener(
            new OnClickListener(){
                public void onClick(View v){
                    myMediaPlayerClass.startMediaPlayer(url, context);
                }
            }
        );
    }
  ...   
}


public class myMediaPlayerClass {
    static MediaPlayer mp=new MediaPlayer();

    public static void startMediaPlayer(  final String myUrl, final Activity myContext){

        new Thread(new Runnable(){

            public void run(){
            string url=myUrl;
                Context context=myContext;
            //***********************************************
            // trying to Toast from here results in crash
        //Toast.makeText(context, "Thread running", Toast.LENGTH_LONG).show();
                //*********************************************************************
            mp.setAudioStreamType(AudioManager.STREAM_MUSIC);

            try {mp.setDataSource(url);} 
            catch (IllegalArgumentException e) {}
            catch (SecurityException e) {} 
            catch (IllegalStateException e) {} 
            catch (IOException e) {}

            mp.setOnPreparedListener(new OnPreparedListener() {
            @Override
                public void onPrepared(MediaPlayer paramMediaPlayer){}
                    });

            mp.setOnBufferingUpdateListener(new OnBufferingUpdateListener() {
                @Override
                public void onBufferingUpdate(MediaPlayer mp, int percent) {}
                });

        try {mp.prepare();} 
        catch (IllegalStateException e) {} 
        catch (IOException e) {}

        mp.setVolume(1, 1);
        mp.start();
            }   
    }).start();

    }
 }

Answer 1

您无法直接从非UI线程显示吐司。是的，你可以通过实施runOnUiThread来实现。

runOnUiThread(new Runnable() {
                            public void run() {
                                Toast.makeText(getApplicationContext(), "Your message", Toast.LENGTH_LONG).show();
                                }
                            });

在不同的线程上显示Toast消息......

Answer 2

在run（）方法中使用它

Toast.makeText(getApplicationContext(),"toast msg here",Toast.LENGTH_SHORT).show();

显示来自与MainActivity不同的类中的线程的Toast消息

2 个答案: