NullPointerException异常:需要的println中的邮件机器人 [英] NullPointerException : println needs a message in android
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问题描述
在我的媒体播放器,我从SD卡播放歌曲。它显示了错误的NullPointerException异常:需要的println消息E在机器人。我试过很长一段时间,但我不知道原因。请帮助我。
code:
尝试{
媒体播放器=新的MediaPlayer();
mediaPlayer.setDataSource(/ SD卡/ t1.mp3);
seek.setMax(mediaPlayer.getDuration());
媒体播放器prepare()。
mediaPlayer.start();
mediaPlayer.setOnCompletionListener(本);
}
赶上(例外前){
Log.e(SD卡-ERR2:,ex.getMessage()); //空指针异常:需要的println消息
}
登录猫:
05-16 19:27:54.491:ERROR / AndroidRuntime(6889):由:显示java.lang.NullPointerException:需要的println消息
05-16 19:27:54.491:ERROR / AndroidRuntime(6889):在android.util.Log.println(本机方法)
05-16 19:27:54.491:ERROR / AndroidRuntime(6889):在android.util.Log.e(Log.java:208)
05-16 19:27:54.491:ERROR / AndroidRuntime(6889):在com.seek.bar.media3.onCreate(media3.java:43)
05-16 19:27:54.491:ERROR / AndroidRuntime(6889):在android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-16 19:27:54.491:ERROR / AndroidRuntime(6889):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459)
05-16 19:27:54.491:ERROR / AndroidRuntime(6889):11 ...更多
解决方案
在捕捞,使用:
字符串ERR =(ex.getMessage()== NULL)SD卡失败:ex.getMessage();
Log.e(SD卡-ERR2:ERR);
in my media player i play a song from sdcard. it shows error as NullPointerException : println needs a message e in android. i tried long time but i do not know the reason .please assist me.
code:
try {
mediaPlayer = new MediaPlayer();
mediaPlayer.setDataSource("/sdcard/t1.mp3");
seek.setMax(mediaPlayer.getDuration());
mediaPlayer.prepare();
mediaPlayer.start();
mediaPlayer.setOnCompletionListener(this);
}
catch(Exception ex){
Log.e("sdcard-err2:",ex.getMessage()); // null pointer exception : println needs a message
}
Log cat:
05-16 19:27:54.491: ERROR/AndroidRuntime(6889): Caused by: java.lang.NullPointerException: println needs a message
05-16 19:27:54.491: ERROR/AndroidRuntime(6889): at android.util.Log.println(Native Method)
05-16 19:27:54.491: ERROR/AndroidRuntime(6889): at android.util.Log.e(Log.java:208)
05-16 19:27:54.491: ERROR/AndroidRuntime(6889): at com.seek.bar.media3.onCreate(media3.java:43)
05-16 19:27:54.491: ERROR/AndroidRuntime(6889): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-16 19:27:54.491: ERROR/AndroidRuntime(6889): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459)
05-16 19:27:54.491: ERROR/AndroidRuntime(6889): ... 11 more
解决方案
In the catch, use:
String err = (ex.getMessage()==null)?"SD Card failed":ex.getMessage();
Log.e("sdcard-err2:",err);
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