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android - 问题用房间数据库填充微调器 android kotlin

问题描述

我想在 kotlin 中使用房间数据库填充微调器，但微调器中的项目不同。项目的数量是真实的。正是我想在类别类中制作标题的 ArrayList并在片段中的微调器中显示它们

@Entity(tableName = "cat_table")

class Category(val title: String,
               val fulType: Int,
               val SaleP: Long,
               val BuyP: Long,
               var created: Date = Date()
            ) {

    @PrimaryKey(autoGenerate = true)
    var id: Int = 0
}`

通过这个想要在 ArrayList 中显示所有标题并设置为 spinner

private fun initData() {
        val packageTypesAdapter = context?.let {ArrayAdapter<Any>(it,android.R.layout.simple_spinner_item)}
        catViewModel!!.allCats.observe(viewLifecycleOwner, Observer { packageTypes ->
            packageTypes?.forEach {packageTypesAdapter!!.add(it)}
        })
        spinner2.adapter = packageTypesAdapter

        spinner2.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
            override fun onItemSelected(adapterView: AdapterView<*>, view: View, i: Int, l: Long) {
                Toast.makeText(context, "$packageTypesAdapter", Toast.LENGTH_SHORT).show()

                //if (i == 0) {
                //    loadAllTodos()
                //} else {
                //   val string: String = parent.getItemAtPosition(position).toString()
                //   loadFilteredTodos(string)
                //}
            }
            override fun onNothingSelected(adapterView: AdapterView<*>) {
            }
        }
}`

如果使用此查询

@get:Query("SELECT * FROM cat_table WHERE title ")
 val allCatTitle: LiveData<List<Category>>

spinner 没有什么可显示的，下面的查询就像这张图片

@get:Query("SELECT * FROM cat_table ORDER BY created DESC")
val allCatByDate: LiveData<List<Category>>

请检查照片

标签： androidkotlin

解决方案

以防其他人遇到同样的问题。这是我前一段时间的做法（Kotlin）。

道

@Query("SELECT deviceName FROM device_table WHERE deviceType = :deviceType")
fun getDevice(deviceType: String): LiveData<List<String>>

存储库

fun getDevice(deviceType: String): LiveData<List<String>> {
    return deviceDao.getDevice(deviceType)
}

视图模型

fun getDevice(deviceType: String): LiveData<List<String>> {
  return repository.getDevice(deviceType)
}

最后在我的片段中：

private fun initSpinnerData() {
    val spinner3 = view?.findViewById<Spinner>(R.id.spinnerRecord_devices)

    if (spinner3 != null) {
        val allDevices = context?.let {
            ArrayAdapter<Any>(it, R.layout.spinner_text)
        }
        mDevicesViewModel.getDevice("Appliance")
            .observe(viewLifecycleOwner, { devices ->
                devices?.forEach {
                    allDevices?.add(it)
                }
            })
        spinner3.adapter = allDevices

        spinner3.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
            override fun onItemSelected(
                parent: AdapterView<*>?,
                view: View?,
                position: Int,
                id: Long
            ) {
                Toast.makeText(requireContext(), "$allDevices", Toast.LENGTH_LONG).show()
            }

            override fun onNothingSelected(parent: AdapterView<*>?) {
                TODO("Not yet implemented")
            }
        }
    }
}

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