Android studio 在kotlin中关闭应用程序时，如何使用room database deleteAll（）？

我已经为historyactivity设置了roomdatabase，并且可以使用insert方法。 现在，当我单击我的historyactivity时，数据仍然显示为RecyclerViewItems。 但我想在关闭构建应用程序时重置数据。我怎么做？有人能帮忙吗？ 在我的DAO中，你可以看到所有的乐趣，所以当我关闭我的应用程序时，我如何使用它？？ 历史.kt

@Entity(tableName = "history")

class History(@PrimaryKey(autoGenerate = true) var id: Long?,
              @ColumnInfo(name= "item") var item:String?,
              @ColumnInfo(name = "title") var title:String?,
              @ColumnInfo(name = "price") var price:Int?,
              @ColumnInfo(name = "Image") var Image:String?

) {
    constructor(): this(null,"","",0,"")
}

@Dao
interface HistoryDao {
    @Query("SELECT * FROM history")
    fun getAll(): List<History>

    @Insert(onConflict = REPLACE )
    fun insert(history: History)

    @Query("DELETE from history")
    fun deleteAll(): List<History>
}

历史活动

class HistoryActivity : AppCompatActivity(), SwipeRefreshLayout.OnRefreshListener {




    private var historyDb: HistoryDB? = null
    private var historyList = listOf<History>()
    lateinit var adapter: HistoryitemReclycerViewAdapter


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_history)

        historyDb = HistoryDB.getInstance(this)
        adapter = HistoryitemReclycerViewAdapter(this, historyList)

        val r = Runnable {

            try {
                historyList = historyDb?.HistoryDB()?.getAll()!!
                adapter = HistoryitemReclycerViewAdapter(this, historyList)
                adapter.notifyDataSetChanged()

                swipeRefreshLo.setOnRefreshListener(this)
                recyclerview.adapter = adapter
                recyclerview.layoutManager = LinearLayoutManager(this)
            } catch (e: Exception) {

            }

        }

        val thread = Thread(r)
        thread.start()

    }
    override fun onRefresh() {
        swipeRefreshLo.isRefreshing = false
    }

    override fun onDestroy() {
        HistoryDB.destoryInstance()
        historyDb =null
        super.onDestroy()
    }


}

---

似乎您需要一个内存中的数据库。您可以使用而不是Room.databaseBuilder。这是此生成器的文档：

为内存中的数据库创建RoomDatabase.Builder。存储在内存中的信息 进程终止时，数据库将消失。 一旦建立了数据库，就应该保留对它的引用并重新使用它

---

你核对我的答案了吗？如果它对你有用，请接受它

class HistoryActivity : AppCompatActivity(), SwipeRefreshLayout.OnRefreshListener {




    private var historyDb: HistoryDB? = null
    private var historyList = listOf<History>()
    lateinit var adapter: HistoryitemReclycerViewAdapter


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_history)

        historyDb = HistoryDB.getInstance(this)
        adapter = HistoryitemReclycerViewAdapter(this, historyList)

        val r = Runnable {

            try {
                historyList = historyDb?.HistoryDB()?.getAll()!!
                adapter = HistoryitemReclycerViewAdapter(this, historyList)
                adapter.notifyDataSetChanged()

                swipeRefreshLo.setOnRefreshListener(this)
                recyclerview.adapter = adapter
                recyclerview.layoutManager = LinearLayoutManager(this)
            } catch (e: Exception) {

            }

        }

        val thread = Thread(r)
        thread.start()

    }
    override fun onRefresh() {
        swipeRefreshLo.isRefreshing = false
    }

    override fun onDestroy() {
        HistoryDB.destoryInstance()
        historyDb =null
        super.onDestroy()
    }


}