Question

我是Scala的新手，因为它是我在学校为入门CS课程所教授的。我不确定为什么我会收到此错误：

/home/ubuntu/Documents/Scala/Self/timeConvertIf.scala:12: error: type mismatch;
 found   : String
 required: Int
    val finalString = displayHours+":"("0"*(2-min.length))+min+":"+("0"*(2-sec.length))+sec
                                              ^
one error found

代码：

import io.StdIn._
print("Enter the number of seconds. ")
val totalSeconds = readInt()

if (totalSeconds > 0) {
    val displaySeconds = totalSeconds%60
    val totalMinutes = totalSeconds/60
    val displayMinutes = totalMinutes%60
    val displayHours = totalMinutes/60
    val sec = displaySeconds.toString
    val min = displayMinutes.toString
    val finalString = displayHours+":"("0"*(2-min.length))+min+":"+("0"*(2-sec.length))+sec
    println(finalString)
}
else {
    println("This only works for a positive number of seconds.")
}

我了解类型不匹配错误是什么，但我不知道为什么我会收到错误显示错误的原因。非常感谢任何帮助！

Answer 1

您在第一个+和":"之间缺少一个("0" * (2 - min.length))：

val finalString = displayHours + ":" + ("0" * (2 - min.length)) + min + ":" + ("0" * (2 - sec.length)) + sec

Answer 2

您错过+前面的("0"*(2-min.length))：

val finalString = displayHours + ":" + ("0"*(2-min.length)) + min + 
                                 ":" + ("0"*(2-sec.length)) + sec

您还可以使用f"$num%02d"数字格式，如下所示：

val finalString = f"${displayHours}:${displayMinutes}%02d:${displaySeconds}%02d"

Answer 3

我想解释一下为什么你会得到这个＆＃34;怪异的＆＃34;错误信息。

如果你缩进一点，留一些空间在令牌之间，你可以看得更清楚：

import io.StdIn._
print("Enter the number of seconds. ")
val totalSeconds = 3600 // readInt()

if (totalSeconds > 0) {
  val displaySeconds = totalSeconds % 60
  val totalMinutes = totalSeconds / 60
  val displayMinutes = totalMinutes % 60
  val displayHours = totalMinutes / 60
  val sec = displaySeconds.toString
  val min = displayMinutes.toString
  val finalString = 
    displayHours + ":" + // <---- you missed this '+'
    ("0" * (2 - min.length)) + min + ":" + 
    ("0" * (2 - sec.length)) + sec
  println(finalString)
} else {
  println("This only works for a positive number of seconds.")
}

发生的事情是：您忘记了+，而是写下了":" (foo)，其中foo的类型为String。现在，编译器将它置于方法应用程序":".apply(foo)中（如果你写下来，它总是这样做）类似于f(x)，其中f不是方法。方法apply在String上不存在，但存在于＆＃34; pimped＆＃34; RichString，字符串":"自动转换为apply(i: Int)。方法RichString on i期望一个整数i，并返回该字符串的library(cowplot) A <- vare.dist.long %>% ggplot(aes(x = Var1, y = Var2, fill = value)) + geom_tile() + scale_fill_viridis(direction = 1) + theme(axis.text.x = element_blank(), axis.title.x = element_blank(), plot.margin = unit(c(1,1,-1.5,1), "cm") ## Note the -1.5, it tells the grob to print itself 1.5 cm below its normal position. ) #/theme B <- vare.data %>% dplyr::select(-c(Var2, value)) %>% unique %>% arrange(Var1_Annotated) %>% mutate(highN = medcode_chr(N, 0, 1), highP = medcode_chr(P, 0, 1), highK = medcode_chr(K, 0, 1)) %>% dplyr::select(-c(N,P,K, Var1, Var1_Annotated)) %>% gather(key, value, -Var1_chr) %>% filter(value == 1) %>% ggplot(aes(x = Var1_chr, y = key, color = key)) + geom_point() + theme(axis.text.x = element_text(angle = 270, hjust = 0, vjust = 0.5), axis.text.y = element_blank(), axis.title.y = element_blank(), plot.margin = unit(c(0,1,1,1), "cm")) + coord_fixed(ratio = 0.3) cowplot::plot_grid(A,B, nrow = 2, align = "v")个字符。这就是您收到错误消息的原因 ＆＃34;需要Int但找到String＆＃34; 。

Scala类型不匹配错误时间转换程序

3 个答案: