如何解决android中的Nullpoint问题

Question

这是MainActivity中的代码 MainActivity.java:541

@Override
public void onSaveInstanceState (Bundle savedInstanceState) {
    super.onSaveInstanceState(savedInstanceState);
    savedInstanceState.putInt("mCurrentChapter", mCurrentChapter);
    savedInstanceState.putInt("index", mPager.getCurrentItem());
    ////Log.e("SaveInstance", mCurrentChapter + " " + mPager.getCurrentItem());
}

我没有看到任何问题。

java.lang.NullPointerException
            at com.techexpert4u.duaaadhkaar.MainActivity.onSaveInstanceState(MainActivity.java:541)
            at android.app.Activity.performSaveInstanceState(Activity.java:1153)
            at android.app.Instrumentation.callActivityOnSaveInstanceState(Instrumentation.java:1223)
            at android.app.ActivityThread.performStopActivityInner(ActivityThread.java:3175)
            at android.app.ActivityThread.handleStopActivity(ActivityThread.java:3234)
            at android.app.ActivityThread.access$1100(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1223)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)

        at dalvik.system.NativeStart.main(Native Method)