android - 如何在 MainActivity 的框架布局中加载默认 fragment ？

Question

我在 mainActivity 中有 2 个 fragment 和 frameLayout。每当我运行我的应用程序时，我都希望将我的 Fragment1 加载到位于 mainActivity 中的 frameLayout default 中。

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.prank.fragmentbackstack.MainActivity">

<FrameLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/frame"
    >

</FrameLayout>
</RelativeLayout>

fragment 类

import android.widget.Button;
    import android.widget.TextView;
    public class Frag extends Fragment {
        String Tag1="frag1";

        Button b;

        public View onCreateView(LayoutInflater inflater, ViewGroup viewGroup, Bundle saveInstanceState)
        {View view = inflater.inflate(R.layout.fragment, viewGroup, false);
            b=(Button)view.findViewById(R.id.button);

            return view;
        }
    }

Answer 1

使用此代码动态添加您的 fragment

// Create new fragment and transaction
Fragment newFragment = new ExampleFragment();
FragmentTransaction transaction = getFragmentManager().beginTransaction();

// Replace whatever is in the fragment_container view with this fragment,
// and add the transaction to the back stack if needed
transaction.replace(R.id.fragment_container, newFragment);
transaction.addToBackStack(null);

// Commit the transaction
transaction.commit();