我有两个片段，首先（start_fragment）应显示应用程序何时启动，并具有2个按钮，1个按钮用于关闭应用程序（declineButton），第二个隐藏此片段并显示主片段（webview_fragment）.如果用户按同意按钮，应用程序下次启动时间已在主片段中（webview_fragment）.我如何保存该用户按下同意按钮？我试图创建布尔变量，但不能'I don“我无法想象如何将fragment中button的新值放到mainactivity中的变量中。
MainActivity.kt

package com.example.webviewapp

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle

class MainActivity : AppCompatActivity() {
    var firstlauch: Boolean = true
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        if (firstlauch == true) {
            supportFragmentManager
                .beginTransaction()
                .replace(R.id.fullcreen_holder, start_fragment())
                .commit()
        } else {
            supportFragmentManager
                .beginTransaction()
                .replace(R.id.webview_holder, webview_fragment())
        }
    }
}

起始片段.kt

package com.example.webviewapp

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button

class start_fragment : Fragment() {

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?

    ): View? {
        val view = inflater.inflate(R.layout.layout_start_fragment, container, false)
        val agreeButton: Button = view.findViewById(R.id.privacy_agree)
        val declineButton: Button = view.findViewById(R.id.privacy_decline)
        agreeButton.setOnClickListener {
            val fragment = webview_fragment()
            val transaction = fragmentManager?.beginTransaction()
            transaction?.remove(this)?.replace(R.id.webview_holder, fragment)?.commit()
        }
        declineButton.setOnClickListener {
            requireActivity().finishAndRemoveTask()
        }
        return view
    }
}