fragment的动态加载

class MainActivity2 : AppCompatActivity() {
    private val mainfragment by lazy {
        MainActivity2Fragment()
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.main_activity2_activity)
        for (i in 1..8){
            Log.i("tag-->","mainfragment$i")
            //动态加载fragment
            supportFragmentManager.beginTransaction()
                .replace(R.id.container, mainfragment)
                .commitNow()
        }
    }

}