Android：无法添加/替换片段

Question

我正在尝试向我的应用添加新片段。
但是此片段为空。

我究竟做错了什么？

片段启动：

ConvertOptions fragment = (ConvertOptions) getSupportFragmentManager()
                    .findFragmentByTag(Utils.CONVERT_FRAGMENT_TAG);

            if (fragment != null)
            {
                getSupportFragmentManager()
                        .beginTransaction()
                        .add(R.id.container, fragment, Utils.CONVERT_FRAGMENT_TAG)
                        .commit();
            }

片段类的代码：

    public class ConvertOptions extends Fragment
{
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.convert_options_fragment, null);

        return view;
    }
}

XML：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/options_convert_fragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:weightSum="1">


<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="New Button"
    android:id="@+id/button2"
    android:layout_gravity="center_horizontal" />

Answer 1

//首先初始化新片段

 ConvertOptions fragment = new ConvertOptions();

        if (fragment != null)
        {
            getSupportFragmentManager()
                    .beginTransaction()
                    .add(R.id.container, fragment, Utils.CONVERT_FRAGMENT_TAG)
                    .commit();
        }

Answer 2

只要这样做：

ConvertOptions mConvertOptions = new ConvertOptions();
FragmentManager fragmentManager = getFragmentManager();
FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.replace(R.id.content_frame, mConvertOptions);
fragmentTransaction.commit();