Nếu chúng ta sử dụng Kotlin thì nó ngắn hơn. Ví dụ về lớp phản hồi để cung cấp nhật ký cuộc gọi:
import android.content.Context
import android.database.Cursor
import android.provider.CallLog.Calls.*
class CallsLoader {
fun getCallLogs(context: Context): List<List<String?>> {
val c = context.applicationContext
val projection = arrayOf(CACHED_NAME, NUMBER, TYPE, DATE, DURATION)
val cursor = c.contentResolver.query(
CONTENT_URI,
projection,
null,
null,
null,
null
)
return cursorToMatrix(cursor)
}
private fun cursorToMatrix(cursor: Cursor?): List<List<String?>> {
val matrix = mutableListOf<List<String?>>()
cursor?.use {
while (it.moveToNext()) {
val list = listOf(
it.getStringFromColumn(CACHED_NAME),
it.getStringFromColumn(NUMBER),
it.getStringFromColumn(TYPE),
it.getStringFromColumn(DATE),
it.getStringFromColumn(DURATION)
)
matrix.add(list.toList())
}
}
return matrix
}
private fun Cursor.getStringFromColumn(columnName: String) =
getString(getColumnIndex(columnName))
}
Chúng tôi cũng có thể chuyển đổi con trỏ sang bản đồ:
fun getCallLogs(context: Context): Map<String, Array<String?>> {
val c = context.applicationContext
val projection = arrayOf(CACHED_NAME, NUMBER, TYPE, DATE, DURATION)
val cursor = c.contentResolver.query(
CONTENT_URI,
projection,
null,
null,
null,
null
)
return cursorToMap(cursor)
}
private fun cursorToMap(cursor: Cursor?): Map<String, Array<String?>> {
val arraySize = cursor?.count ?: 0
val map = mapOf(
CACHED_NAME to Array<String?>(arraySize) { "" },
NUMBER to Array<String?>(arraySize) { "" },
TYPE to Array<String?>(arraySize) { "" },
DATE to Array<String?>(arraySize) { "" },
DURATION to Array<String?>(arraySize) { "" }
)
cursor?.use {
for (i in 0 until arraySize) {
it.moveToNext()
map[CACHED_NAME]?.set(i, it.getStringFromColumn(CACHED_NAME))
map[NUMBER]?.set(i, it.getStringFromColumn(NUMBER))
map[TYPE]?.set(i, it.getStringFromColumn(TYPE))
map[DATE]?.set(i, it.getStringFromColumn(DATE))
map[DURATION]?.set(i, it.getStringFromColumn(DURATION))
}
}
return map
}
