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どのコンテキストで使用する必要がありMediaPlayer.create()ますか?

私はActivity.thisすべてのMediaPlayerオブジェクトで使用しています。しかし、ヌルポインタ例外が発生していると思います。

コンテキストは、アンドロイドまたはその他で強制終了の理由になる可能性がありますか?

ここで " com.bhavin.panara.kbc" はパッケージ名です。そして108行目はmediaplayer.start().

コードは次のとおりです。

MediaPlayer mp;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    .
    .
    .
    mp = MediaPlayer.create(PlayScreen.this, R.raw.sound);
    .
    .
    mp.start(); // 108th line.

    }

これが私の丸太猫レポートです。

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.bhavin.panara.kbc/com.bhavin.panara.kbc.PlayScreen}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1999)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2026)
at android.app.ActivityThread.access$600(ActivityThread.java:127)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1174)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4506)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:809)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:576)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.bhavin.panara.kbc.PlayScreen.onCreate(PlayScreen.java:108)
at android.app.Activity.performCreate(Activity.java:4479)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1050)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1963)
... 11 more
4

3 に答える 3

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

    //set the layout of the Activity
    setContentView(R.layout.activity_songs);

    //initialize views
    initializeViews();
}

public void initializeViews(){
    songName = (TextView) findViewById(R.id.songName);
    songName.setText("khmosia.mp3");
    mediaPlayer = MediaPlayer.create(this, Uri.parse("android.resource://" + getPackageName() + "/" + R.raw.khmosia));
    mediaPlayer.start();
    timeElapsed = mediaPlayer.getCurrentPosition();


    finalTime = mediaPlayer.getDuration();
    duration = (TextView) findViewById(R.id.songDuration);
    timeElapsed = mediaPlayer.getCurrentPosition();

    seekbar = (SeekBar) findViewById(R.id.seekBar);
    seekbar.setProgress((int) timeElapsed);

    durationHandler.postDelayed(updateSeekBarTime, 100);
    seekbar.setMax((int) finalTime);
    seekbar.setClickable(false);
    Runnable updateSeekBarTime = new Runnable() {
        public void run() {
            //get current position
            timeElapsed = mediaPlayer.getCurrentPosition();
            //set seekbar progress
            seekbar.setProgress((int) timeElapsed);
            //set time remaing
            double timeRemaining = finalTime - timeElapsed;
            duration.setText(String.format("%d min, %d sec", TimeUnit.MILLISECONDS.toMinutes((long) timeRemaining), TimeUnit.MILLISECONDS.toSeconds((long) timeRemaining) - TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes((long) timeRemaining))));

            //repeat yourself that again in 100 miliseconds
            durationHandler.postDelayed(this, 100);
            mediaPlayer.pause();

        }
    };
于 2015-03-05T09:11:01.620 に答える