Kotlin Android 如何将Fragment下拉列表选中值传递到另一个Activity

实现方案 #

你之前的尝试逻辑错位了：不需要提前监听下拉框选中事件，点击预约按钮时直接读取三个下拉控件的当前选中值即可，具体修改如下：

第一步 修改CalendarFragment.kt的按钮点击逻辑 #

直接在bookADateButton的点击回调中读取三个下拉框的当前文本，封装到Intent中传递到确认页：

package com.example.mydoctor

import ...

class CalendarFragment : Fragment() {
    private lateinit var binding: FragmentCalendarBinding1

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setHasOptionsMenu(true)
    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        binding = FragmentCalendarBinding1.inflate(layoutInflater)

        // 日期下拉适配
        val itemsDates = resources.getStringArray(R.array.dates)
        val adapterDate = ArrayAdapter(requireContext(), list_dates, itemsDates)
        binding.autocompleteTextViewDateDropdown.setAdapter(adapterDate)

        // 时间下拉适配
        val itemsTimes = resources.getStringArray(R.array.times)
        val adapterTime = ArrayAdapter(requireContext(), list_times, itemsTimes)
        binding.autocompleteTextViewTimeDropdown.setAdapter(adapterTime)

        // 补充你缺失的医生下拉适配，可根据你实际的控件ID调整
        val itemsDoctors = resources.getStringArray(R.array.doctors)
        val adapterDoctor = ArrayAdapter(requireContext(), list_doctors, itemsDoctors)
        binding.autocompleteTextViewDoctorDropdown.setAdapter(adapterDoctor)

        binding.bookADateButton.setOnClickListener {
            // 直接读取三个下拉当前选中值
            val selectedDate = binding.autocompleteTextViewDateDropdown.text.toString()
            val selectedTime = binding.autocompleteTextViewTimeDropdown.text.toString()
            val selectedDoctor = binding.autocompleteTextViewDoctorDropdown.text.toString()

            // 可选加非空校验，避免用户漏选
            if (selectedDate.isEmpty() || selectedTime.isEmpty() || selectedDoctor.isEmpty()) {
                Toast.makeText(requireContext(), "请完善所有预约信息", Toast.LENGTH_SHORT).show()
                return@setOnClickListener
            }

            // 封装参数传递到确认页
            val intent = Intent(requireContext(), ConfirmationActivity::class.java).apply {
                putExtra("SELECTED_DATE", selectedDate)
                putExtra("SELECTED_TIME", selectedTime)
                putExtra("SELECTED_DOCTOR", selectedDoctor)
            }
            startActivity(intent)
        }

        return binding.root
    }
}

第二步 修改ConfirmationActivity.kt接收参数并展示 #

接收传递过来的三个参数，设置到确认页对应文本控件上即可，假设确认页的展示文本控件ID为tvConfirmation：

package com.example.mydoctor

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.widget.TextView

class ConfirmationActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_confirmation)

        // 接收参数
        val selectedDate = intent.getStringExtra("SELECTED_DATE") ?: ""
        val selectedTime = intent.getStringExtra("SELECTED_TIME") ?: ""
        val selectedDoctor = intent.getStringExtra("SELECTED_DOCTOR") ?: ""

        // 拼接展示文本，可根据你的UI需求调整格式
        val confirmText = "预约信息确认：\n出诊医生：$selectedDoctor\n预约日期：$selectedDate\n预约时间：$selectedTime"
        // 设置到确认页文本控件
        findViewById<TextView>(R.id.tvConfirmation).text = confirmText

        Log.d("conf", "预约信息：$confirmText")
    }
}

之前代码的问题说明 #

你把下拉框的OnItemClickListener设置逻辑放在了按钮点击回调中，只有点击按钮时才会给下拉框绑定选中监听，逻辑完全错位；且就算触发了选中回调，你定义的selectedValue是回调内部的局部变量，外部无法访问，自然拿不到选中值。

内容的提问来源于stack exchange，提问作者Dimitris Sidiropoulos