Android FragmentManager BackStackRecord.run throwing NullPointerException

错误：
java.lang.NullPointerException
11-15 09:04:21.023: E/AndroidRuntime(4057):     at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:591)
11-15 09:04:21.023: E/AndroidRuntime(4057):     at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1416

if (mCurTransaction != null) {
mCurTransaction.commitAllowingStateLoss();
//            if (manager != null)
//                manager.executePendingTransactions();

原因：当FragmentManager add，attach，remove，dettach时如果fragment为null，如add(null)
则容易mCurTransaction.commitAllowingStateLoss（） 方法可能出现这个错误。

解决方法：在执行这些方法时判断fragment是否为null。 如if(fragment != null) add(fragment);