这是我的堆栈跟踪：

FATAL EXCEPTION: main
java.lang.NullPointerException
at com.example.test.fragments.LoadingFragment$1.run(LoadingFragment.java:66)
at android.os.Handler.handleCallback(Handler.java:725)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:5041)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
at dalvik.system.NativeStart.main(Native Method)

我的片段的第66行：

Line 66 of my Fragment:

FragmentTransaction ft = fm.beginTransaction();

FM是得到这样的：

fm is gotten like this:

android.support.v4.app.FragmentManager fm = getFragmentManager();

我的片段延伸 android.support.v4.app.Fragment ，这些都是我的进口：

My Fragment extends android.support.v4.app.Fragment, these are my imports:

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentTransaction;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

我从来没有见过，我得到空的FragmentManager任何人有一个想法？

i never had seen that i got null for a FragmentManager anybody got an Idea?

推荐答案

在清洗和藏汉重建我的项目，因为重新启动我的测试设备，这又莫名其妙地工作。

After cleaning and rebuilding my project aswell as restarting my testing device, this worked again somehow.