kotlin - 在 Kotlin 中将变量传递到父级的构造函数中

Question

我正在尝试将变量从子类传递到父类的构造函数。

父类的构造函数由(Context!, String!, SQLiteDatabase.CursorFactory!, Int)组成。

我可以轻松做到

class TodoListDBHandler(context: Context, databaseName: String, factory: SQLiteDatabase.CursorFactory, databaseVersion: Int): 
    SQLiteOpenHelper(context, databaseName, factory, databaseVersion)

但我想直接在类中指定数据库名称和版本，而不是每次调用构造函数时都指定它，因为我可能会犯错误。

我当前的代码:

class TodoListDBHandler(context: Context, databaseName: String, factory: SQLiteDatabase.CursorFactory, databaseVersion: Int): 
    SQLiteOpenHelper(context, databaseName, factory, databaseVersion) {

    val databaseFileName = "todoList.db"
    val databaseVersion = 1

    override fun onCreate(db: SQLiteDatabase?) {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

    override fun onUpgrade(db: SQLiteDatabase?, oldVersion: Int, newVersion: Int) {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }
}

如上所述，我希望能够将我指定的变量传递给父级的构造函数。

编辑:这是所需的代码，但在 Java 中

public TodoListDBHandler(Context context, SQLiteDatabase.CursorFactory factory) {
    // databaseFileName and databaseVersion are already specified inside the class
    super(context, databaseFileName, factory, databaseVersion)
}

Answer 1

您可以直接在父类(super class)构造函数中传递常量参数。

class TodoListDBHandler(context: Context, factory: SQLiteDatabase.CursorFactory)
        : SQLiteOpenHelper(context, "todoList.db", factory, 1) {

        override fun onCreate(db: SQLiteDatabase) {
        }

        override fun onUpgrade(db: SQLiteDatabase, oldVersion: Int, newVersion: Int) {
        }
}