会在ListView中选择错误的项目位置吗

Question

我正试图通过以下示例实现一个搜索函数，通过关键字在SQLite数据库中进行搜索。这是我的代码：

AndroidManifest.xml

<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:roundIcon="@mipmap/ic_launcher_round"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
<action android:name="android.intent.action.SEARCH"/>
</intent-filter>
<meta-data
android:name="android.app.searchable"
android:resource="@xml/searchable"/>
</activity>
<activity android:name=".AddCarActivity">
</activity>
<activity android:name=".ViewActivity">
</activity>
</application>

主活动.kt

class MainActivity : AppCompatActivity() {
lateinit var cars: ListView
lateinit var car_adapter: CarAdapter
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
cars = findViewById(R.id.cars)
val add: FloatingActionButton = findViewById(R.id.add)
add.setOnClickListener {
startActivityForResult(Intent(this, AddCarActivity::class.java), 1000)
}
cars.onItemClickListener = AdapterView.OnItemClickListener { _, _, i, _ ->
val cursor = CarDatabase(this).getCarList()
cursor.moveToPosition(i)
val intent = Intent(this, ViewActivity::class.java)
intent.putExtra("car", cursor.getString(1))
startActivity(intent)
}
getCars()
}
fun getCars() {
car_adapter = CarAdapter(this, CarDatabase(this).getCarList())
cars.adapter = car_adapter
}
override fun onCreateOptionsMenu(menu: Menu?): Boolean {
menuInflater.inflate(R.menu.menu, menu)
val manager: SearchManager = getSystemService(Context.SEARCH_SERVICE) as SearchManager
val search = menu!!.findItem(R.id.search).actionView as SearchView
search.setSearchableInfo(manager.getSearchableInfo(componentName))
val context: Context = this
search.setOnQueryTextListener(object : SearchView.OnQueryTextListener {
override fun onQueryTextSubmit(query: String?): Boolean {
if (query!!.isNotEmpty()) {
val cursor: Cursor = CarDatabase(context).getCarListByKeyword(query)!!
Toast.makeText(context, "${cursor.count} record(s) found!", Toast.LENGTH_LONG).show()
car_adapter.swapCursor(cursor)
}
return false
}
override fun onQueryTextChange(newText: String?): Boolean {
if (newText!!.isNotEmpty()) {
val cursor: Cursor = CarDatabase(context).getCarListByKeyword(newText)!!
car_adapter.swapCursor(cursor)
} else
getCars()
return false
}
})
return true
}
}

AddCarActivity.kt

class AddCarActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_add_car)
val add: ImageButton = findViewById(R.id.add_car)
add.setOnClickListener {
val car: EditText = findViewById(R.id.car_et)
if (CarDatabase(this).addCar(car.text.toString())) {
Toast.makeText(this, "Car added!", Toast.LENGTH_SHORT).show()
setResult(1000)
finish()
} else
Toast.makeText(this, "Please try again!", Toast.LENGTH_SHORT).show()
}
}
}

ViewActivity.kt

class ViewActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_view)
val car: TextView = findViewById(R.id.car_v)
car.text = intent.getStringExtra("car")
}
}

车载适配器.kt

class CarAdapter(context: Context, cursor: Cursor?) :
CursorAdapter(context, cursor, 0) {
private var mInflater: LayoutInflater? = null
override fun newView(context: Context, cursor: Cursor, parent: ViewGroup): View {
val view = mInflater!!.inflate(R.layout.cars_list, parent, false)
val holder = ViewHolder()
holder.car = view.findViewById(R.id.car)
view.tag = holder
return view
}
override fun bindView(view: View, context: Context, cursor: Cursor) {
val holder = view.tag as ViewHolder
holder.car!!.text = cursor.getString(cursor.getColumnIndex(CarDatabase.CAR))
}
internal class ViewHolder {
var car: TextView? = null
}
init {
mInflater = context.getSystemService(Context.LAYOUT_INFLATER_SERVICE) as LayoutInflater?
}
}

CarDatabase.kt

class CarDatabase(context: Context) : SQLiteOpenHelper(context, NAME, null, VERSION) {
companion object {
const val NAME = "Cars.db"
const val VERSION = 1
const val TABLE = "Cars"
const val ID = "_id"
const val CAR = "Car"
}
private var db: SQLiteDatabase = this.writableDatabase
override fun onCreate(db: SQLiteDatabase) {
db.execSQL("CREATE TABLE $TABLE ($ID INTEGER PRIMARY KEY AUTOINCREMENT, $CAR TEXT);")
}
override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
db.execSQL("DROP TABLE IF EXISTS $TABLE")
onCreate(db)
}
fun getCarList(): Cursor {
val cursor = db.rawQuery("SELECT * FROM $TABLE", null)
if (!cursor.moveToFirst())
cursor.close()
return cursor
}
fun addCar(car: String): Boolean {
val values = ContentValues()
values.put(CAR, car)
return db.insert(TABLE, null, values) > 0
}
fun getCarListByKeyword(search: String): Cursor? {
val cursor = db.rawQuery("SELECT rowid as $ID, $CAR FROM $TABLE WHERE $CAR LIKE '%$search%'", null)
if (cursor == null) {
return null
} else if (!cursor.moveToFirst()) {
cursor.close()
return null
}
return cursor
}
}

以下是我在测试设备上执行应用程序后创建的示例列表像这样。此示例应用程序执行以下操作：通过单击项目打开"查看"活动，并显示所选项目，如下所示。例如，通过选择奥迪，您将看到奥迪。

问题出现在搜索功能中。例如，如果我搜索梅赛德斯-奔驰，然后单击它，则在ViewActivity中会显示奥迪如下。或者丰田->梅赛德斯-奔驰或奥迪Q5>雷克萨斯等。搜索后，似乎会在列表视图中选择错误的位置。我该如何解决这个问题？如果我不能解释一些可以理解的事情，请告诉我。

Answer 1

看起来，即使您将DB光标交换为适配器中的搜索视图，也不会使用它从数据库中实际获取项目：(在您的onItemClickListener中(

val cursor = CarDatabase(this).getCarList()
cursor.moveToPosition(i)

您应该从适配器而不是CarDatabase(this(.getCarList((获取当前光标，然后使用它，即

val cursor = car_adapter.cursor
cursor.moveToPosition(i)

希望能有所帮助。干杯