我正在准备一个小型音频播放器，并显示来自设备的音频歌曲列表，但每当我点击任何一首歌曲播放时，每次都会收到错误。
完整 Logcat ：
06-10 15:52:28.440: W/dalvikvm(3732): threadid=1: thread exiting with uncaught exception (group=0x41e0d2a0)
06-10 15:52:28.450: E/AndroidRuntime(3732): FATAL EXCEPTION: main
06-10 15:52:28.450: E/AndroidRuntime(3732): java.lang.IllegalStateException: Could not execute method of the activity
06-10 15:52:28.450: E/AndroidRuntime(3732): at android.view.View$1.onClick(View.java:3699)
06-10 15:52:28.450: E/AndroidRuntime(3732): at android.view.View.performClick(View.java:4223)
06-10 15:52:28.450: E/AndroidRuntime(3732): at android.view.View$PerformClick.run(View.java:17275)
06-10 15:52:28.450: E/AndroidRuntime(3732): at android.os.Handler.handleCallback(Handler.java:615)
06-10 15:52:28.450: E/AndroidRuntime(3732): at android.os.Handler.dispatchMessage(Handler.java:92)
06-10 15:52:28.450: E/AndroidRuntime(3732): at android.os.Looper.loop(Looper.java:137)
06-10 15:52:28.450: E/AndroidRuntime(3732): at android.app.ActivityThread.main(ActivityThread.java:4921)
06-10 15:52:28.450: E/AndroidRuntime(3732): at java.lang.reflect.Method.invokeNative(Native Method)
06-10 15:52:28.450: E/AndroidRuntime(3732): at java.lang.reflect.Method.invoke(Method.java:511)
06-10 15:52:28.450: E/AndroidRuntime(3732): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1036)
06-10 15:52:28.450: E/AndroidRuntime(3732): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:803)
06-10 15:52:28.450: E/AndroidRuntime(3732): at dalvik.system.NativeStart.main(Native Method)
06-10 15:52:28.450: E/AndroidRuntime(3732): Caused by: java.lang.reflect.InvocationTargetException
06-10 15:52:28.450: E/AndroidRuntime(3732): at java.lang.reflect.Method.invokeNative(Native Method)
06-10 15:52:28.450: E/AndroidRuntime(3732): at java.lang.reflect.Method.invoke(Method.java:511)
06-10 15:52:28.450: E/AndroidRuntime(3732): at android.view.View$1.onClick(View.java:3694)
06-10 15:52:28.450: E/AndroidRuntime(3732): ... 11 more
06-10 15:52:28.450: E/AndroidRuntime(3732): Caused by: java.lang.NullPointerException
06-10 15:52:28.450: E/AndroidRuntime(3732): at com.example.syncing.MainActivity.songPicked(MainActivity.java:98)
06-10 15:52:28.450: E/AndroidRuntime(3732): ... 14 more
06-10 15:52:38.065: I/Process(3732): Sending signal. PID: 3732 SIG: 9
检查我的完整源代码 MainActivity.java： -
public class MainActivity extends Activity implements MediaPlayerControl {
//song list variables
private ArrayList<Song> songList;
private ListView songView;
//service
private MusicService musicSrv;
private Intent playIntent;
//binding
private boolean musicBound=false;
//controller
private MusicController controller;
//activity and playback pause flags
private boolean paused=false, playbackPaused=false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//retrieve list view
songView = (ListView)findViewById(R.id.song_list);
//instantiate list
songList = new ArrayList<Song>();
//get songs from device
getSongList();
//sort alphabetically by title
Collections.sort(songList, new Comparator<Song>(){
public int compare(Song a, Song b){
return a.getTitle().compareTo(b.getTitle());
}
});
//create and set adapter
SongAdapter songAdt = new SongAdapter(this, songList);
songView.setAdapter(songAdt);
//setup controller
setController();
}
//connect to the service
private ServiceConnection musicConnection = new ServiceConnection(){
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
MusicBinder binder = (MusicBinder)service;
//get service
musicSrv = binder.getService();
//pass list
musicSrv.setList(songList);
musicBound = true;
}
@Override
public void onServiceDisconnected(ComponentName name) {
musicBound = false;
}
};
//start and bind the service when the activity starts
@Override
protected void onStart() {
super.onStart();
if(playIntent==null){
playIntent = new Intent(this, MusicService.class);
bindService(playIntent, musicConnection, Context.BIND_AUTO_CREATE);
startService(playIntent);
}
}
//user song select
public void songPicked(View view){
musicSrv.setSong(Integer.parseInt(view.getTag().toString()));
musicSrv.playSong();
if(playbackPaused){
setController();
playbackPaused=false;
}
controller.show(0);
}
//method to retrieve song info from device
public void getSongList(){
//query external audio
ContentResolver musicResolver = getContentResolver();
Uri musicUri = android.provider.MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
Cursor musicCursor = musicResolver.query(musicUri, null, null, null, null);
//iterate over results if valid
if(musicCursor!=null && musicCursor.moveToFirst()){
//get columns
int titleColumn = musicCursor.getColumnIndex
(android.provider.MediaStore.Audio.Media.TITLE);
int idColumn = musicCursor.getColumnIndex
(android.provider.MediaStore.Audio.Media._ID);
int artistColumn = musicCursor.getColumnIndex
(android.provider.MediaStore.Audio.Media.ARTIST);
//add songs to list
do {
long thisId = musicCursor.getLong(idColumn);
String thisTitle = musicCursor.getString(titleColumn);
String thisArtist = musicCursor.getString(artistColumn);
songList.add(new Song(thisId, thisTitle, thisArtist));
}
while (musicCursor.moveToNext());
}
}
@Override
public boolean canPause() {
return true;
}
@Override
public boolean canSeekBackward() {
return true;
}
@Override
public boolean canSeekForward() {
return true;
}
@Override
public int getAudioSessionId() {
return 0;
}
@Override
public int getBufferPercentage() {
return 0;
}
@Override
public int getCurrentPosition() {
if(musicSrv!=null && musicBound && musicSrv.isPng())
return musicSrv.getPosn();
else return 0;
}
@Override
public int getDuration() {
if(musicSrv!=null && musicBound && musicSrv.isPng())
return musicSrv.getDur();
else return 0;
}
@Override
public boolean isPlaying() {
if(musicSrv!=null && musicBound)
return musicSrv.isPng();
return false;
}
@Override
public void pause() {
playbackPaused=true;
musicSrv.pausePlayer();
}
@Override
public void seekTo(int pos) {
musicSrv.seek(pos);
}
@Override
public void start() {
musicSrv.go();
}
//set the controller up
private void setController(){
controller = new MusicController(this);
//set previous and next button listeners
controller.setPrevNextListeners(new View.OnClickListener() {
@Override
public void onClick(View v) {
playNext();
}
}, new View.OnClickListener() {
@Override
public void onClick(View v) {
playPrev();
}
});
//set and show
controller.setMediaPlayer(this);
controller.setAnchorView(findViewById(R.id.song_list));
controller.setEnabled(true);
}
private void playNext(){
musicSrv.playNext();
if(playbackPaused){
setController();
playbackPaused=false;
}
controller.show(0);
}
private void playPrev(){
musicSrv.playPrev();
if(playbackPaused){
setController();
playbackPaused=false;
}
controller.show(0);
}
@Override
protected void onPause(){
super.onPause();
paused=true;
}
@Override
protected void onResume(){
super.onResume();
if(paused){
setController();
paused=false;
}
}
@Override
protected void onStop() {
controller.hide();
super.onStop();
}
@Override
protected void onDestroy() {
stopService(playIntent);
musicSrv=null;
super.onDestroy();
}
}
答案 0 :(得分：0)
您没有设置标记，因此视图没有。您在view.getTag（）。toString（）
上获取null或者将setTag设置到该视图或在调用之前检查它是否为null：
if(view.getTag() != null) {
...
}