Question

我使用Fragment在TabLayout中保存我的内容。在里面，我有Button。当我尝试在Fragment类中实例化时，我得到以下错误：

var idx = sheet
    .Cells["1:1"]
    .First(c => c.Value.ToString() == "Birthdate")
    .Start
    .Column;

sheet.Column(idx).Style.Numberformat.Format = "mm-dd-yy";

以下是 onCreateView（...）

中的代码

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)

这是我的Fragment XML布局：

public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle 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);

        return inflater.inflate(R.layout.fragment_account, mFragmentAccount,true);
    }

我错过了什么？

谢谢

Answer 1

看起来你试图在充气之前找到它们。首先给视图充气，然后访问它的孩子。

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;
}

Answer 2

您正试图从您的活动中获取您的视图。你必须给你的片段充气。

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

Answer 3

正如Slapmer和Victor指出的那样，NP错误是因为您在创建（膨胀）View之前尝试访问View。

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

最好在View中添加访问onViewCreated(...)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);

}

快乐的编码！

NullPointerException初始化片段中的视图

3 个答案: