我正在尝试创建列表项的房间数据库。我在这里遵循这个例子:https://medium.com/mindorks/room-kotlin-android-architecture-components-71cad5a1bb35 https://medium.com/mindorks/room-kotlin-android-architecture-components-71cad5a1bb35
这是我的数据类:
@Entity(tableName = "itemData")
data class ItemData(@PrimaryKey(autoGenerate = true) var id: Long? = null,
@ColumnInfo(name = "text") var text: String,
@ColumnInfo(name = "checked") var checked: Boolean
)
The DAO:
@Dao
interface ItemDataDAO {
@Insert(onConflict = REPLACE)
fun insert(itemData: ItemData) : Long
}
数据库:
@Database(entities = arrayOf(ItemData::class), version = 1)
abstract class ItemDatabase() : RoomDatabase() {
abstract fun itemDataDao(): ItemDataDAO
companion object {
private var INSTANCE: ItemDatabase? = null
fun getInstance(context: Context): ItemDatabase? {
if (INSTANCE == null) {
synchronized(ItemDatabase::class) {
INSTANCE = Room.databaseBuilder(context.getApplicationContext(),
ItemDatabase::class.java, "items.db")
.build()
}
}
return INSTANCE
}
fun destroyInstance() {
INSTANCE = null
}
}
}
工作线程:
class DbWorkerThread(threadName: String) : HandlerThread(threadName) {
private lateinit var mWorkerHandler: Handler
override fun onLooperPrepared() {
super.onLooperPrepared()
mWorkerHandler = Handler(looper)
}
fun postTask(task: Runnable) {
mWorkerHandler.post(task)
}
}
这是调用插入函数的监听器:
editText.setOnEditorActionListener { v, actionId, event ->
return@setOnEditorActionListener when (actionId) {
EditorInfo.IME_ACTION_DONE -> {
createItem(editText)
true
}
else -> false
}
}
这是被调用以插入项目的函数:
fun createItem(editText: EditText) {
var text = editText.text.toString().trim()
var itemData = ItemData(text = text, checked = false)
var id : Long? = 0
val task = Runnable {
id = mDb?.itemDataDao()?.insert(itemData)
println("inserted $id")
}
mDbWorkerThread.postTask(task)
}
但 ID 始终为 0,因此只会插入一项。任何人都可以看到问题吗?
我也尝试过删除默认的null
的值id
,但它给出了相同的结果。