scala2.11知识总结 1

最新推荐文章于 2023-08-06 23:03:53 发布

shadowsama

最新推荐文章于 2023-08-06 23:03:53 发布

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分类专栏： scala 文章标签： scala

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这篇博客总结了Scala 2.11版本中关于Tuple的重大变化，指出在Scala 2.10.4中由于限制，最多只能有22个属性，而在Scala 2.11中这一限制被放宽，允许处理更多列的数据，特别是在Spark中可以直接从数据库读取超过22列的数据。博主强调了这个改进对于大数据处理的重要性，并建议做相关笔记。

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object _22 {


  def main(args: Array[String]): Unit = {

    val _22 = new Tuple22(1, 2, 3, 4, 5, 6, 7, 8, 9, 10
      , 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)

    print(_22)


//    Error:(19, 16) Implementation restriction: case classes cannot have more than 22 parameters.
//    case class Tuple23(i1: Int, i2: Int, i3: Int, i4: Int, i5: Int, i6: Int, i7: Int, i8: Int, i9: Int, i10: Int, i11: Int, i12: Int, i13: Int, i14: Int, i15: Int, i16: Int, i17: Int, i18: Int, i19: Int, i20: Int, i21: Int, i22: Int, i23: Int) {
    case class Tuple23(i1: Int, i2: Int, i3: Int, i4: Int, i5: Int, i6: Int, i7: Int, i8: Int, i9: Int, i10: Int, i11: Int, i12: Int, i13: Int, i14: Int, i15: Int, i16: Int, i17: Int, i18: Int, i19: Int, i20: Int, i21: Int, i22: Int, i23: Int) {
    }

    val _23 = new Tuple23(1, 2, 3, 4, 5, 6, 7, 8, 9, 10
      , 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
    print(_23)



  }

}

如上程序在scala2.10.4下会报错，因为版本原因，scala限制对象的属性最多为22个，也可自定义对象 extends Product23

在scala2.11 中貌似取消了1~22的限定 现在spark可以直接重数据库中读取大于22列的数据了，做下笔记！！