【Debug-Fragment】..v4.app.FragmentActivity.getSupportFragmentManager()' on a null object reference

错误：

java.lang.NullPointerException: Attempt to invoke virtual method 'android.support.v4.app.FragmentManager android.support.v4.app.FragmentActivity.getSupportFragmentManager()' on a null object reference
        at xxx.assistant.fragment.xxxxxx.replaceFragment(xxxxxxxx.java:148)
        at xxx.assistant.fragment.xxxxxx.access$200(xxxxxx.java:41)
        at xxx.assistant.fragment.xxxxxx$2.onRequestKnightSuccess(xxxxxx.java:119)
        at vertu.assistant.request.xxxx$1.onResponse(xxxx.java:209)

用在自定义的Fragment中，该Fragment继承自“android.support.v4.app.Fragment;”

代码：

    private void replaceFragment(Fragment fragment) {
        FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.replace(R.id.fl_homepage_follow_fragment_content, fragment);
        fragmentTransaction.commit();
    }

参考：https://blog.csdn.net/suyan_why/article/details/52574197

感觉用“getActivity()”不太妥，想换成在Fragment中适用的方式

参考：https://www.cnblogs.com/earl-yongchang/p/5747860.html

感觉使用【getFragmentManager()】更方便一下，所以把

FragmentManager fragmentManager = getActivity().getSupportFragmentManager();

替换成：

FragmentManager fragmentManager = getFragmentManager();

暂时不报错，再看看吧~