【发布时间】：2015-03-27 04:20:57
【问题描述】：
我有一个名为HelperActivity.class 的活动，我还有另一个扩展SherlockFragment 的类。 SherlockFragment 有三个方法playAudio(),pauseAudio(),stopAudio();
像这样;
public void playAudio() {
mediaPlayer.start();
btn_play.setEnabled(false);
pDialog.dismiss();
btn_pause.setEnabled(true);
btn_stop.setEnabled(true);
}
我想从HelperActivty.class 调用这个方法。我尝试了很多方法，但每次都得到NullPointerException。我尝试发送上下文并尝试将我的方法更改为静态但结果相同。请帮助。
头等舱
public class HelperActivity extends Activity
二等;
public class RadioStream extends SherlockFragment implements OnClickListener, OnTouchListener, OnCompletionListener, OnBufferingUpdateListener
错误；
FATAL EXCEPTION: main
01-28 02:40:50.390: E/AndroidRuntime(2915): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.fedorvlasov.mostban/com.fedorvlasov.mostban.HelperActivity}: java.lang.NullPointerException
01-28 02:40:50.390: E/AndroidRuntime(2915): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2262)
01-28 02:40:50.390: E/AndroidRuntime(2915): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2316)
01-28 02:40:50.390: E/AndroidRuntime(2915): at android.app.ActivityThread.access$700(ActivityThread.java:158)
01-28 02:40:50.390: E/AndroidRuntime(2915): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1296)
01-28 02:40:50.390: E/AndroidRuntime(2915): at android.os.Handler.dispatchMessage(Handler.java:99)
01-28 02:40:50.390: E/AndroidRuntime(2915): at android.os.Looper.loop(Looper.java:176)
01-28 02:40:50.390: E/AndroidRuntime(2915): at android.app.ActivityThread.main(ActivityThread.java:5365)
01-28 02:40:50.390: E/AndroidRuntime(2915): at java.lang.reflect.Method.invokeNative(Native Method)
01-28 02:40:50.390: E/AndroidRuntime(2915): at java.lang.reflect.Method.invoke(Method.java:511)
01-28 02:40:50.390: E/AndroidRuntime(2915): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1102)
01-28 02:40:50.390: E/AndroidRuntime(2915): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:869)
01-28 02:40:50.390: E/AndroidRuntime(2915): at dalvik.system.NativeStart.main(Native Method)
01-28 02:40:50.390: E/AndroidRuntime(2915): Caused by: java.lang.NullPointerException
01-28 02:40:50.390: E/AndroidRuntime(2915): at com.fedorvlasov.mostban.RadioStream.playAudio(RadioStream.java:310)
01-28 02:40:50.390: E/AndroidRuntime(2915): at com.fedorvlasov.mostban.HelperActivity.onCreate(HelperActivity.java:52)
01-28 02:40:50.390: E/AndroidRuntime(2915): at android.app.Activity.performCreate(Activity.java:5326)
01-28 02:40:50.390: E/AndroidRuntime(2915): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1097)
01-28 02:40:50.390: E/AndroidRuntime(2915): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2225)
01-28 02:40:50.390: E/AndroidRuntime(2915): ... 11 more
01-28 02:40:52.054: I/Process(2915): Sending signal. PID: 2915 SIG: 9
【问题讨论】：
-
你知道 ActionBarSherlock 已被弃用，对吧？
-
是的@MD 是对的...您的 mediaPlayer 变量为空...您必须先处理 mediaPlayer 的空值。
-
你是如何从
RadioStream调用playAudio()方法的？ -
@ρяσѕρєя K 正常通话。案例 R.id.btn_play: playAudio();休息;
-
@M D 其实媒体播放器正在运行，为什么会为空？
标签： java android class methods nullpointerexception