scala循环将日期字符串添加到seq中

Question

我正在尝试将字符串中的日期从数组添加到序列中，同时确定今天是否是周末。

import java.text.SimpleDateFormat
import java.util.{Calendar, Date, GregorianCalendar}
import org.apache.spark.sql.SparkSession

val arrDateEsti=dtfBaseNonLong.select("AAA").distinct().collect.map(_(0).toString);
    
var dtfDateCate = Seq(
      ("0000", "0")
    );
    
for (a<-0 to arrDateEsti.length-1){
      val dayDate:Date = dateFormat.parse(arrDateEsti(a));
      val cal=new GregorianCalendar
      cal.setTime(dayDate);
    
  if (cal.get(Calendar.DAY_OF_WEEK)==1 || cal.get(Calendar.DAY_OF_WEEK)==7){
    dtfDateCate:+(arrDateEsti(a),"1")
  }else{
    dtfDateCate:+(arrDateEsti(a),"0")
  }
};

scala> dtfDateCate
res20: Seq[(String, String)] = List((0000,0))

它returns相同的初始序列。但是，如果我运行一个单一的元素，它就可以工作。出了什么问题？

scala>   val dayDate:Date = dateFormat.parse(arrDateEsti(0));
dayDate: java.util.Date = Thu Oct 15 00:00:00 CST 2020

scala>   cal.setTime(dayDate);

scala>   if (cal.get(Calendar.DAY_OF_WEEK)==1 || cal.get(Calendar.DAY_OF_WEEK)==7){
     |     dtfDateCate:+(arrDateEsti(0),"1")
     |   }else{
     |     dtfDateCate:+(arrDateEsti(0),"0")
     |   };
res14: Seq[(String, String)] = List((0000,0), (20201015,0))

Answer 1

我想这就是你想要做的事情。

import java.time.LocalDate
import java.time.DayOfWeek.{SATURDAY, SUNDAY}
import java.time.format.DateTimeFormatter

                  //replace with dtfBaseNonLong.select(... code
val arrDateEsti = Seq("20201015", "20201017")  //place holder

val dtFormat = DateTimeFormatter.ofPattern("yyyyMMdd")
val dtfDateCate = ("0000", "0") +:
                  arrDateEsti.map { dt =>
                    val day = LocalDate.parse(dt,dtFormat).getDayOfWeek()
                    if (day == SATURDAY || day == SUNDAY) (dt, "1")
                    else                                  (dt, "0")
                  }
//dtfDateCate = Seq((0000,0), (20201015,0), (20201017,1))

Answer 2

对，应该是seqDateCate=seqDateCate:+(arrDateEsti(a),"1")

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