思路

使用Bundle来进行通信
Bundle类用作携带数据，它类似于Map，用于存放key-value名值对形式的值。相对于Map，它提供了各种常用类型的putXxx()/getXxx()方法，如:putString(/getString()和putInt()/getInt(),putXxx()用于往Bundle对象放入数据，getXxx()方法用于从Bundle对象里获取数据。Bundle的内部实际上是使用了HashMap类型的变量来存放putXxx(方法放入的值:

一、示例

1.1、MainActivity.java

package com.example.fragmentmanagers;

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

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

import java.io.BufferedOutputStream;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Button button = findViewById(R.id.btn);
        button.setOnClickListener(this);
        Button button2 = findViewById(R.id.btn_2);
        button2.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.btn:
            //通信
                Bundle bundle = new Bundle();
                bundle.putString("message", " love you");
                BlankFragment1 bf = new BlankFragment1();
                bf.setArguments(bundle);

                replaceFragment(bf);
                break;
            case R.id.btn_2:
                replaceFragment(new ItemFragment() );

        }
    }

    // 动态切换fragment
    private void replaceFragment(Fragment fragment) {
        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction transation = fragmentManager.beginTransaction();
        transation.replace(R.id.framelayout, fragment);
        //添加这个表示用了栈
        transation.addToBackStack(null);
        transation.commit();
    }
}

1.2、activity_main.xml

<?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"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/btn"
        android:text="@string/change"></Button>
    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/btn_2"
        android:text="@string/replace"></Button>

    <FrameLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/framelayout"
        android:background="@color/colorAccent"></FrameLayout>

</LinearLayout>

1.3、创建Fragement

这里是BlankFragment1.java,随便创建一个就好
修改生命周期函数onCreate()

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Bundle bundle = this.getArguments();
        String string = bundle.getString("message");
        Log.d(TAG, "onCreate: " + string);

    }

二、测试

点击CHANGE按钮