我在使用 Android 媒体播放器时遇到问题,我正在做一些小测验,并且我有方法 correctAnswer(),我在其中创建带有一些声音的 MediaPlayer,然后准备它,然后启动它,但是我得到了这个 NullPointerException 错误。
我正在尝试播放 mp3 声音。
这是该方法正确答案():
private void correctAnswer() {
MediaPlayer correctSound = MediaPlayer.create(this, R.raw.correct);
try {
correctSound.prepare();
} catch (IllegalStateException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
correctSound.start();
Toast.makeText(getApplicationContext(), "Correct answer +1",
Toast.LENGTH_SHORT).show();
progressBar.incrementProgressBy(1);
tvProgress.setText(progressBar.getProgress() + "/20");
generateQuestion();
endGame();
}
这是LogCat:
09-04 21:21:30.546: E/AndroidRuntime(513): Uncaught handler: thread main exiting due to uncaught exception
09-04 21:21:30.567: E/AndroidRuntime(513): java.lang.NullPointerException
09-04 21:21:30.567: E/AndroidRuntime(513): at com.example.americansportsquiz.PlayStageActivity.correctAnswer(PlayStageActivity.java:121)
09-04 21:21:30.567: E/AndroidRuntime(513): at com.example.americansportsquiz.PlayStageActivity.onClick(PlayStageActivity.java:75)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.view.View.performClick(View.java:2364)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.view.View.onTouchEvent(View.java:4179)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.widget.TextView.onTouchEvent(TextView.java:6541)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.view.View.dispatchTouchEvent(View.java:3709)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
09-04 21:21:30.567: E/AndroidRuntime(513): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1659)
09-04 21:21:30.567: E/AndroidRuntime(513): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.app.Activity.dispatchTouchEvent(Activity.java:2061)
09-04 21:21:30.567: E/AndroidRuntime(513): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1643)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.view.ViewRoot.handleMessage(ViewRoot.java:1691)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.os.Handler.dispatchMessage(Handler.java:99)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.os.Looper.loop(Looper.java:123)
09-04 21:21:30.567: E/AndroidRuntime(513): at android.app.ActivityThread.main(ActivityThread.java:4363)
09-04 21:21:30.567: E/AndroidRuntime(513): at java.lang.reflect.Method.invokeNative(Native Method)
09-04 21:21:30.567: E/AndroidRuntime(513): at java.lang.reflect.Method.invoke(Method.java:521)
09-04 21:21:30.567: E/AndroidRuntime(513): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
09-04 21:21:30.567: E/AndroidRuntime(513): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
09-04 21:21:30.567: E/AndroidRuntime(513): at dalvik.system.NativeStart.main(Native Method)
编辑正如我所说,这是测验应用程序,它会为 7 个正确答案播放声音,但它在 8 个时失败,并给我这个空指针异常。在它以 8 个正确答案失败之前,它一直给我这个警告。
09-04 21:41:33.086: W/MediaPlayer(598): info/warning (1, 44)