Java 片段中的NullPointerException初始化视图

我使用Fragment在TabLayout中保存我的内容。 里面有一个按钮。当我尝试在Fragment类中实例化时，出现以下错误：

com.example.fanjavaid.tablayout E/AndroidRuntime: FATAL EXCEPTION: main
      java.lang.NullPointerException
          at com.example.fanjavaid.tablayout.fragment.AccountFragment.onCreateView(AccountFragment.java:27)
          at android.support.v4.app.Fragment.performCreateView(Fragment.java:2080)
          at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1108)
          at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1290)
          at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:801)
          at android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:1638)
          at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:679)
          at android.support.v4.app.FragmentStatePagerAdapter.finishUpdate(FragmentStatePagerAdapter.java:166)
          at android.support.v4.view.ViewPager.populate(ViewPager.java:1240)
          at android.support.v4.view.ViewPager.populate(ViewPager.java:1088)
          at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1614)

这是我在onCreateView（…）中的代码

下面是我的片段XML布局：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/fragment_account"
    android:padding="@dimen/activity_horizontal_margin"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true"
        android:text="Hello Android!"/>

    <Button
        android:id="@+id/add_person"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:gravity="center"
        android:text="Add People"/>

</RelativeLayout>

我错过了什么

---

谢谢

看起来您正在尝试在充气之前查找视图。 首先膨胀视图，然后访问其子对象

请试试这个

public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View mFragmentAccount = inflater.inflate(R.layout.fragment_account, container,true);

    mBtnAddPerson = (Button) mFragmentAccount.findViewById(R.id.add_person);
    Typeface font = Typeface.createFromAsset(mFragmentAccount.getContext().getAssets(), "/fonts/Rubik-Regular.ttf");
    mBtnAddPerson.setTypeface(font);

    return mFragmentAccount;
}

---

您正试图从您的活动中获取视图。你必须把你的碎片充气

View rootView = inflater.inflate(R.id.fragment_account, container, false);

---

正如Slapmer和Victor所指出的，NP错误是因为您在创建（膨胀的）

视图之前试图访问
视图

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup viewGroup, Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_account, mFragmentAccount,true);
    }

最好在
onViewCreated（…）
中添加访问
View
的代码，如下所示：

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    RelativeLayout mFragmentAccount = (RelativeLayout) getActivity().findViewById(R.id.fragment_account);
    mBtnAddPerson = (Button) mFragmentAccount.findViewById(R.id.add_person);
    Typeface font = Typeface.createFromAsset(mFragmentAccount.getContext().getAssets(), "/fonts/Rubik-Regular.ttf");
    mBtnAddPerson.setTypeface(font);

}

快乐编码
 你忘了添加stacktrace。请将其添加到您的问题中。是的，请添加日志。问题已更新，谢谢Victor和Slamper回答了您的问题。快乐编码！另外，最好将访问视图的代码放在
onViewCreated（..）
中，您能告诉我NP出现在我建议的代码的哪一行吗？在这一行：
mBtnAddPerson=（按钮）MFFragmentAccount.findViewById（R.id.add\u person）实例化按钮时
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    RelativeLayout mFragmentAccount = (RelativeLayout) getActivity().findViewById(R.id.fragment_account);
    mBtnAddPerson = (Button) mFragmentAccount.findViewById(R.id.add_person);
    Typeface font = Typeface.createFromAsset(mFragmentAccount.getContext().getAssets(), "/fonts/Rubik-Regular.ttf");
    mBtnAddPerson.setTypeface(font);