使用Kotlin中的datepicker比较Firestore时间戳和Date

Question

我正在firestore工作，但时间戳出现了一些问题。我想使用android studio中的datepicker根据日期进行过滤。我只想比较月份和月份的日期。我认为会很好，但是时间问题了，

示例：

firestore：Sat May 18 23:21:20 GMT+07:00 2019
datepicker：Sat May 18 05:46:27 GMT+07:00 2019

下面是一些用于选择时间戳记的代码：

fun initClasses(date: Date, onComplete: () -> Unit){
        currentUserDocRef.get()
            .addOnSuccessListener {
                currentUserDocRefAddClasses.get().addOnSuccessListener { documentSnapshot ->
                    //      Log.d("test", "name: " + it.get("name") + " id: " + it.id)
                    val newClasses = Classes(it.id,"",it.get("name").toString(),"", date)
                    currentUserDocRefAddClasses.document().set(newClasses).addOnSuccessListener {
                        onComplete()
                        Log.d("success1","success")

                    }
                }

            }
    }

日期选择器的代码：

floatingActionButtonClass.setOnClickListener {
            var date = DatePickerDialog
                .OnDateSetListener { view, year, month, dayOfMonth ->
                calendar.set(Calendar.YEAR, year)
                calendar.set(Calendar.MONTH, month)
                calendar.set(Calendar.DAY_OF_MONTH, dayOfMonth)
                    Log.d("tag261", calendar.time.toString())
                    FirestoreUtil.initClasses(calendar.time as Date){
                        toast("berhasil input")
                    }
                }


            DatePickerDialog(
                this, date,
                calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH),
                calendar.get(Calendar.DAY_OF_MONTH)
            ).show()
        }

谢谢