Question

private fun copyDatabase(context: Context): Boolean {
    try {

        val inputStream = context.assets.open(DatabaseHelper.DBNAME)
        val outFileName = DatabaseHelper.DBLOCATION + DatabaseHelper.DBNAME
        val outputStream = FileOutputStream(outFileName)
        val buff = ByteArray(1024)
        var length = 0

        while((length = inputStream.read(buff)) > 0) {
            outputStream.write(buff , 0 , length)
        }

        outputStream.flush()
        outputStream.close()
        Log.w("MainActivity" , "DB copied")
        return true
    } catch (e: Exception) {
        e.printStackTrace()
        return false
    }

}

此代码中的“虽然”无法正常工作，我需要帮助

Answer 1

您似乎正在尝试将InputStream内容复制到OutputStream。为此，您可以在Kotlin中使用InputStream.copyTo扩展功能：

select * from my_table m
inner join  (
  select  column1, max(column3) col3
  from my_table 
  group by column1 
  ) t on t. column1 = m.column1 and t.col3 = m.column3

Answer 2

您可以这样解决：

    ...
    var length = inputStream.read(buff)

    while(length  > 0) {
        outputStream.write(buff , 0 , length)
        length = inputStream.read(buff)
    }
    ...

但是@Ilya是对的，您在Kotlin的土地上，最好使用Kotlin提供的工具

分配不是表达式，并且在此上下文中仅允许表达式

2 个答案: