私は、nullポインタ例外iはのAndroidメディアプレーヤーNULLポインタ例外
MediaPlayer mp = new MediaPlayer();
と
public int check()
{
if(mp!=null)
{
return 1;
}
else
{
return 2;
}
}
を助けていない使用して試してみましたが何であるかを知っています。活性 ComponentInfo {com.openaisearch.www.musicplayer/com.openaisearch.www.musicplayer.MainActivity}を開始できません: れるjava.langこれはエラーイムgetting-
java.lang.RuntimeExceptionあります.NullPointerException:ヌル オブジェクト参照に仮想メソッドを呼び出す試み 'ブールcom.openaisearch.www.musicplayer.Music.check()'
public class MainActivity extends AppCompatActivity {
ArrayList<String> mSongsList = new ArrayList<>() ;
ArrayList<Long> SongsPath = new ArrayList<>() ;
Button btnPlay;
Music mService;
SeekBar seekBar;
ListView lv;
boolean mBound = false;
private ServiceConnection mConnection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName className,
IBinder service) {
Music.LocalBinder binder = (Music.LocalBinder) service;
mService = binder.getService();
mBound = true;
}
@Override
public void onServiceDisconnected(ComponentName arg0) {
mBound = false;
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Intent intent = new Intent(this, Music.class);
bindService(intent, mConnection, Context.BIND_AUTO_CREATE);
startService(intent);
btnPlay = (Button) findViewById(R.id.buttonPlay);
seekBar = (SeekBar) findViewById(R.id.seekBar);
lv = (ListView) findViewById(R.id.list);
getAudioList();
ArrayAdapter arrayAdapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1,mSongsList);
lv.setAdapter(arrayAdapter);
onSongClick();
setSeekBar();
check();
}
@Override
protected void onStop() {
super.onStop();
if (mBound) {
unbindService(mConnection);
mBound = false;
}
}
public void getAudioList() {
String orderBy = MediaStore.Audio.Media.TITLE ;
String selection = MediaStore.Audio.Media.IS_MUSIC + " != 0";
Cursor mCursor = getContentResolver().query(
MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,
new String[] { MediaStore.Audio.Media.TITLE,
MediaStore.Audio.Media._ID }, selection, null, orderBy);
int count = mCursor.getCount();
while (mCursor.moveToNext()) {
mSongsList.add(mCursor.getString(mCursor
.getColumnIndexOrThrow(MediaStore.Audio.Media.TITLE)));
SongsPath.add(mCursor.getLong(mCursor
.getColumnIndexOrThrow(MediaStore.Audio.Media._ID)));
}
mCursor.close();
}
public void onSongClick()
{
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
mService.playSong(SongsPath.get(position));
if(btnPlay.getText() == "Play")
{
btnPlay.setText("Pause");
}
}
});
}
public void onButtonClick(View view) {
int a = mService.stopMusic();
if(a == 1)
{
btnPlay.setText("Play");
}
else if (a ==2)
{
btnPlay.setText("Pause");
}
}
public void check()
{
boolean check = mService.check();
}
public void setSeekBar()
{
seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
if (fromUser)
{
mService.setProg(progress*1000);
}
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
}
});
}
}
Service-
public class Music extends Service {
Long b;
MediaPlayer mp;
private final IBinder mBinder = new LocalBinder();
public class LocalBinder extends Binder {
Music getService() {
return Music.this;
}
}
public void playSong(Long a) {
if (a!= b)
{ if(mp!=null)
{
mp.stop();
mp.release();
mp=null;
}
b =a;
Uri contentUri = ContentUris.withAppendedId(
android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, a);
mp = new MediaPlayer();
mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
try {
mp.setDataSource(getApplicationContext(), contentUri);
mp.prepare();
mp.setLooping(true);
mp.start();
} catch (IOException e) {
e.printStackTrace();
}
}
}
public int stopMusic()
{
if(mp.isPlaying())
{
mp.pause();
return 1;
}
else if (mp!=null)
{
mp.start();
return 2;
}
else
{
return 0;
}
}
public void setProg(int a)
{ if(mp!=null)
{
mp.seekTo(a);
}
}
public boolean check()
{
if(mp!=null)
{
return true;
}
else
{
return false;
}
}
@Override
public IBinder onBind(Intent intent) {
return mBinder;
}
}
iは1と2のリターンで代わりにブールのint型を使用して疲れていはまだ –
に動作しないと、正確にNPEがで指している行、[OK]を同じエラーに –
を与えますか? –