Android Studio FragmentManager

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:id="@+id/ll"
    android:orientation="vertical"
    >
  <FrameLayout
      android:layout_weight="1"
      android:layout_gravity="top"
      android:layout_width="match_parent"
      android:layout_height="match_parent"></FrameLayout>
  <RadioGroup
      android:id="@+id/rg"
      android:background="#88A29D9D"
      android:orientation="horizontal"
      android:layout_gravity="bottom"
      android:layout_width="match_parent"
      android:layout_height="50dp">
    <RadioButton
        android:id="@+id/rd1"
        android:drawableTop="@drawable/tp"
        android:layout_weight="1"
        android:text="联系人"
        android:textColor="@drawable/text"
        android:button="@null"
        android:gravity="center"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        ></RadioButton>
    <RadioButton
        android:id="@+id/rd2"
        android:textColor="@drawable/text"
        android:drawableTop="@drawable/tp1"
        android:layout_weight="1"
        android:text="信息"
        android:gravity="center"
        android:button="@null"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        ></RadioButton>
  </RadioGroup>


</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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".BlankFragment">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="11111111111" />

</FrameLayout>

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".BlankFragment2">

    <!-- TODO: Update blank fragment layout -->
    <TextView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:text="2222222222" />

</FrameLayout>

package com.example.day4;

import android.os.Bundle;
import android.widget.LinearLayout;
import android.widget.RadioGroup;

import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;

import java.io.BufferedReader;

public class MainActivity extends AppCompatActivity implements RadioGroup.OnCheckedChangeListener{
    
    

    private LinearLayout ll;
    private RadioGroup rg;
    private FragmentManager manager;
    private BlankFragment2 blankFragment2;
    private   BlankFragment blankFragment;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
    
    
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ll = findViewById(R.id.ll);
        rg = (RadioGroup) findViewById(R.id.rg);

        rg.setOnCheckedChangeListener(this);

         manager=getSupportFragmentManager();

        final  FragmentTransaction fragmentTransaction=manager.beginTransaction();

         blankFragment=new BlankFragment();
         fragmentTransaction.add(R.id.ll,blankFragment);

         blankFragment2=new BlankFragment2();
         fragmentTransaction.add(R.id.ll,blankFragment2);

         fragmentTransaction.hide(blankFragment2);
             fragmentTransaction.commit();

    }
    @Override
    public void onCheckedChanged(RadioGroup radioGroup, int i) {
    
    
        switch (i){
    
    
            case R.id.rd1:
          FragmentTransaction fragmentTransaction1=manager.beginTransaction();
          fragmentTransaction1.hide(blankFragment2);
          fragmentTransaction1.show(blankFragment);
          fragmentTransaction1.commit();
                break;
            case R.id.rd2:
                FragmentTransaction fragmentTransaction2=manager.beginTransaction();
                fragmentTransaction2.hide(blankFragment);
                fragmentTransaction2.show(blankFragment2);
                fragmentTransaction2.commit();
                break;
        }
    }


}

 FragmentManager两个都一样

package com.example.day4;


import android.os.Bundle;

import androidx.fragment.app.Fragment;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;


/**
 * A simple {@link Fragment} subclass.
 */
public class BlankFragment extends Fragment {
    
    


    public BlankFragment() {
    
    
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
    
    
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_blank, container, false);
    }

}