java - 当我回到 kotlin 时，如何将微调器值设置为我在离开页面之前选择的最后一个值

Question

我想确保当我从下拉微调器中选择一个项目并在每次返回页面时离开页面时，最后选择的项目应该是下拉列表的当前值

当我返回页面时，下拉列表中的第一个值是微调器中显示的值，我需要它是微调器中最后选择的值

override fun initialize() {
        val customerLocation = ParentActivity.getCustomerLocation()
        stateItem = ""
        areaItem = ""
        backBtn= PageView?.findViewById(R.id.backBtn)!!
        backBtn.setOnClickListener {
            ParentActivity.removeFragment()
        }

        submitLocationBtn = PageView?.findViewById(R.id.submitLocationBtn)!!
        userLocation = PageView?.findViewById(R.id.userLocation)!!
        stateSpinner = PageView?.findViewById(R.id.stateSpinner)!!
        areaSpinner = PageView?.findViewById(R.id.areaSpinner)!!

        if (customerLocation == null) {
            userLocation.text = ""
        } else {
            userLocation.text = customerLocation!!.Area + ", " + customerLocation!!.State
        }

        stateSpinner.setOnItemSelectedListener(ParentActivity)
        areaSpinner.setOnItemSelectedListener(ParentActivity)

        areaSpinnerAdapter = AreaDropDownAdapter(areaList, ParentActivity)
        areaSpinner?.adapter = areaSpinnerAdapter

        stateSpinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
            override fun onItemSelected(p0: AdapterView<*>?, p1: View?, p2: Int, p3: Long) {
                stateItem = stateList[p2].Name
                getArea(stateItem)
            }

            override fun onNothingSelected(p0: AdapterView<*>?) {

            }

        }

        areaSpinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
            override fun onItemSelected(p0: AdapterView<*>?, p1: View?, p2: Int, p3: Long) {

                areaItem = areaList[p2].Name


            override fun onNothingSelected(p0: AdapterView<*>?) {

            }

        }

        submitLocationBtn.setOnClickListener {
            customerLocation!!.State = stateItem
            customerLocation.Area = areaItem
            var location = customerLocation!!.Area + ", " + customerLocation!!.State
            ParentActivity.getInAppDB().saveCustomerLocation(customerLocation!!)
            userLocation.text = location
            replaceFragment(Home(), removeFragment = false, showBottom = false)
        }

    }

Answer 1

您可以通过以下代码在 Spinner 中选择一个项目

spinner.setSelection(index)

根据您的情况，您可以做的是:

1. 保存所选项目，也许您可​​以使用 SharedPreferences(您的情况:位置名称)

2. 当返回同一 View 时，从 SharedPreferences 中获取所选项目

3. 查找该项目的索引(您的情况:从 stateList 中)

4. 通过spinner.setSelection(index)将找到的索引设置为spinner

应该是这样的

        stateInt = preference.getInt(customerLocation!!.State, 0)
        stateSpinner.setSelection(stateInt)

        stateSpinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
            override fun onItemSelected(p0: AdapterView<*>?, p1: View?, p2: Int, p3: Long) {
                stateItem = stateList[p2].Name
                getArea(stateItem)
                preference.edit {
                    putInt(customerLocation!!.State, stateInt)
                }
            }

            override fun onNothingSelected(p0: AdapterView<*>?) {

            }
        }