第八次

package com.example.myapplication;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

import com.example.myapplication.ui.frist.FristFragment;
import com.example.myapplication.ui.frist.FristViewModel;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        FristFragment fragment=new FristFragment();
        
    }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/frist"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".ui.frist.FristFragment">

    <TextView
        android:id="@+id/message"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="FristFragment"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <fragment
        android:name="com.example.myapplication.ui.frist.FristFragment"
        android:id="@+id/b_1"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Frist" />