Question

public class MainActivity extends Activity implements Runnable,OnSeekBarChangeListener,OnClickListener{


    private Button startMedia,pauseMedia;
    private SeekBar seekBar;
     private MediaPlayer mp;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);
        AudioControl(); 
    }


    private void AudioControl() {
        // TODO Auto-generated method stub
        seekBar = (SeekBar) findViewById(R.id.seekBar1);
        startMedia = (Button) findViewById(R.id.button1);
        pauseMedia = (Button) findViewById(R.id.button2);
        startMedia.setOnClickListener(this);
        pauseMedia.setOnClickListener(this); 
    }


    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
         if (v.equals(startMedia)) {
                if (mp != null && mp.isPlaying()) return;
                if(seekBar.getProgress() > 0) {
                    mp.start();
                    return;
                }
                try {
                    mp.setDataSource("http://videos.oneindia.in/temp/sitaram.mp3");
                } catch (IllegalArgumentException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (SecurityException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (IllegalStateException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                mp.start();                     
                seekBar.setProgress(0);
                seekBar.setMax(mp.getDuration());
                new Thread(this).start();
            }

            if (v.equals(pauseMedia) && mp!=null) {
                mp.pause();
            }       
    }


    @Override
    public void onProgressChanged(SeekBar seekBar, int progress,
            boolean fromUser) {
        // TODO Auto-generated method stub
        if(fromUser) mp.seekTo(progress);

    }


    @Override
    public void onStartTrackingTouch(SeekBar seekBar) {
        // TODO Auto-generated method stub

    }


    @Override
    public void onStopTrackingTouch(SeekBar seekBar) {
        // TODO Auto-generated method stub

    }


    @Override
    public void run() {
        // TODO Auto-generated method stub
        int currentPosition= 0;
        int total = mp.getDuration();
        while (mp!=null && currentPosition<total) {
            try {
                Thread.sleep(1000);
                currentPosition= mp.getCurrentPosition();
            } catch (InterruptedException e) {
                return;
            } catch (Exception e) {
                return;
            }            
            seekBar.setProgress(currentPosition);
        }
    }

}

我想使用seekbar选项从url播放mp3。以下例外即将来临......有人请帮助我

04-02 03:20:24.498: E/AndroidRuntime(1879): FATAL EXCEPTION: main
04-02 03:20:24.498: E/AndroidRuntime(1879): Process: com.example.mediaplayerdemo, PID: 1879
04-02 03:20:24.498: E/AndroidRuntime(1879): java.lang.NullPointerException
04-02 03:20:24.498: E/AndroidRuntime(1879):     at com.example.mediaplayerdemo.MainActivity.onClick(MainActivity.java:52)
04-02 03:20:24.498: E/AndroidRuntime(1879):     at android.view.View.performClick(View.java:4438)
04-02 03:20:24.498: E/AndroidRuntime(1879):     at android.view.View$PerformClick.run(View.java:18422)
04-02 03:20:24.498: E/AndroidRuntime(1879):     at android.os.Handler.handleCallback(Handler.java:733)
04-02 03:20:24.498: E/AndroidRuntime(1879):     at android.os.Handler.dispatchMessage(Handler.java:95)
04-02 03:20:24.498: E/AndroidRuntime(1879):     at android.os.Looper.loop(Looper.java:136)
04-02 03:20:24.498: E/AndroidRuntime(1879):     at android.app.ActivityThread.main(ActivityThread.java:5017)
04-02 03:20:24.498: E/AndroidRuntime(1879):     at java.lang.reflect.Method.invokeNative(Native Method)
04-02 03:20:24.498: E/AndroidRuntime(1879):     at java.lang.reflect.Method.invoke(Method.java:515)
04-02 03:20:24.498: E/AndroidRuntime(1879):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-02 03:20:24.498: E/AndroidRuntime(1879):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-02 03:20:24.498: E/AndroidRuntime(1879):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

试试这个..

您尚未初始化MediaPlayer（mp）尝试初始化并尝试。

mp = new MediaPlayer();

http://typicaljava.blogspot.in/2013/03/streaming-media-player-with-song-url.html

http://android.programmerguru.com/android-mediaplayer-example-play-from-internet/

修改

if (v.equals(startMedia)) { mp = new MediaPlayer(); mp.setAudioStreamType(AudioManager.STREAM_MUSIC); try { mp.setDataSource(url); } catch (IllegalArgumentException e) { e.printStackTrace(); } catch (SecurityException e) { e.printStackTrace(); } catch (IllegalStateException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { mp.prepare(); } catch (IllegalStateException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } mp.start(); seekBar.setMax(mp.getDuration()); new Thread(this).start(); }

媒体播放器不从网址播放mp3

1 个答案: