我得到一个 Int 值应该去的字符串

Question

我正在编写一个程序，将任何基数转换为任何基数，似乎很多代码都随用户输入传递，但突然发生了一些意想不到的事情，其中 decimalNumber 中的值试图添加一个空字符串，当它不能这样做时。这是代码：

package converter
import kotlin.system.exitProcess
import java.math.BigInteger
import java.util.Scanner
var alphabet = listOf("A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z")

fun convertNumberToDecimal(numberToConvert: String, sourceBase: Int): BigInteger { // fix this formula!
  var finalValue = ""
  var elementHolder = (numberToConvert).toMutableList()
  var i = elementHolder.size - 1
  var j = 0
  var decimalNumber = 0.toBigInteger()
  while (j != elementHolder.size) {
    if (elementHolder[j].toString().toUpperCase() in alphabet) {
      elementHolder[j] = (10 + alphabet.indexOf(elementHolder[j].toString())).toChar()
      println(elementHolder[j])
    }
    decimalNumber += (elementHolder[j].toString().toBigInteger() * Math.pow(sourceBase.toDouble(), i.toDouble()).toInt().toBigInteger())
    j++
    i--
  }
  return decimalNumber
}

fun convertDecimalToNewBase(numberToConvert: String, targetBase: Int): Any {
  var checker = 0
  var i = 0
  var power = targetBase
  var sumOfNumbers = 0
  var decimalNumber = numberToConvert.toInt()
  var quotient: String = ""
  var remainder = 0
  var listOfNumbers: MutableList<String> = mutableListOf()
  var finalValue = ""
  var denominator = 0
  
  while (checker < numberToConvert.toInt()) {
    checker = Math.pow(targetBase.toDouble(), i.toDouble()).toInt()
    i++
    if (checker > numberToConvert.toInt()) {
      i -= 2
      checker = Math.pow(targetBase.toDouble(), i.toDouble()).toInt()
      break
    }
  }
  
  while (i != -1) {
    denominator = Math.pow(targetBase.toDouble(), i.toDouble()).toInt()
    remainder = (decimalNumber % denominator)
    quotient = (decimalNumber / denominator).toString()
    if (quotient.toInt() >= 10 && quotient.toInt() <= 36 && targetBase > 10) {
      quotient = alphabet[(quotient.toInt() - 10)]
    }
    listOfNumbers.add(quotient)
    decimalNumber = remainder
    i--
  }
    
  for (each in listOfNumbers) {
    finalValue += each.toString()
  }
  for (each in alphabet) {
    if (each in finalValue) {
      return finalValue
    }
  }
  return finalValue.toBigInteger()
}

fun main() {
  var scanner = Scanner(System.`in`)
  println("Enter two numbers in format: {source base} {target base} (To quit type /exit) ")
  var choice = readLine()!!.toString()
  var splitter = listOf<String>()
  var sourceBase: Int
  var targetBase: Int
  var numberInSourceBase: Any
  var newDecimalNumber: Any
  if (choice == "/exit") {
    exitProcess(0)
  } else {
    splitter = choice.split(" ")
    sourceBase = splitter[0].toInt()
    targetBase = splitter[1].toInt()
  }
  do {
    println("Enter number in base " + sourceBase + " to convert to base " + targetBase + " (To go back type /back) ")
    numberInSourceBase = readLine()!!.toString()
    if (numberInSourceBase == "/back") {
      main()
    }
    if (sourceBase != 10) {
      newDecimalNumber = convertNumberToDecimal(numberInSourceBase.toString(), sourceBase)
      newDecimalNumber = (convertDecimalToNewBase(newDecimalNumber.toString(), targetBase)).toString()
    } else {
      newDecimalNumber = (convertDecimalToNewBase(numberInSourceBase.toString(), targetBase)).toString()
    }
    println("Conversion result: " + newDecimalNumber)
  } while (numberInSourceBase != "/back")
}

这是我收到的错误消息（错误消息下方是用户输入）：

Exception in test #4

java.lang.NumberFormatException: For input string: "    "
    at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:67)
    at java.base/java.lang.Integer.parseInt(Integer.java:654)
    at java.base/java.math.BigInteger.<init>(BigInteger.java:536)
    at java.base/java.math.BigInteger.<init>(BigInteger.java:674)
    at converter.MainKt.convertNumberToDecimal(Main.kt:18)
    at converter.MainKt.main(Main.kt:93)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt:90)
    at converter.MainKt.main(Main.kt)

Please find below the output of your program during this failed test.
Note that the '>' character indicates the beginning of the input line.

---

[last 250 lines of output are shown, 56 skipped]
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 2 29
Enter number in base 2 to convert to base 29 (To go back type /back) 
> 1010011110
Conversion result: N3
Enter number in base 2 to convert to base 29 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 2 32
Enter number in base 2 to convert to base 32 (To go back type /back) 
> 1111000101
Conversion result: U5
Enter number in base 2 to convert to base 32 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 2 35
Enter number in base 2 to convert to base 35 (To go back type /back) 
> 1010010111
Conversion result: IX
Enter number in base 2 to convert to base 35 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 5 2
Enter number in base 5 to convert to base 2 (To go back type /back) 
> 11243
Conversion result: 1100110111
Enter number in base 5 to convert to base 2 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 5 8
Enter number in base 5 to convert to base 8 (To go back type /back) 
> 3021
Conversion result: 602
Enter number in base 5 to convert to base 8 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 5 11
Enter number in base 5 to convert to base 11 (To go back type /back) 
> 1213
Conversion result: 157
Enter number in base 5 to convert to base 11 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 5 14
Enter number in base 5 to convert to base 14 (To go back type /back) 
> 4310
Conversion result: 2D6
Enter number in base 5 to convert to base 14 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 5 17
Enter number in base 5 to convert to base 17 (To go back type /back) 
> 3242
Conversion result: 195
Enter number in base 5 to convert to base 17 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 5 20
Enter number in base 5 to convert to base 20 (To go back type /back) 
> 10130
Conversion result: 1D5
Enter number in base 5 to convert to base 20 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 5 23
Enter number in base 5 to convert to base 23 (To go back type /back) 
> 3213
Conversion result: IJ
Enter number in base 5 to convert to base 23 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 5 26
Enter number in base 5 to convert to base 26 (To go back type /back) 
> 4214
Conversion result: LD
Enter number in base 5 to convert to base 26 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 5 29
Enter number in base 5 to convert to base 29 (To go back type /back) 
> 3403
Conversion result: GE
Enter number in base 5 to convert to base 29 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 5 32
Enter number in base 5 to convert to base 32 (To go back type /back) 
> 3143
Conversion result: D7
Enter number in base 5 to convert to base 32 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 5 35
Enter number in base 5 to convert to base 35 (To go back type /back) 
> 1403
Conversion result: 6I
Enter number in base 5 to convert to base 35 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 8 2
Enter number in base 8 to convert to base 2 (To go back type /back) 
> 637
Conversion result: 110011111
Enter number in base 8 to convert to base 2 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 8 5
Enter number in base 8 to convert to base 5 (To go back type /back) 
> 701
Conversion result: 3244
Enter number in base 8 to convert to base 5 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 8 11
Enter number in base 8 to convert to base 11 (To go back type /back) 
> 773
Conversion result: 421
Enter number in base 8 to convert to base 11 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 8 14
Enter number in base 8 to convert to base 14 (To go back type /back) 
> 1623
Conversion result: 495
Enter number in base 8 to convert to base 14 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 8 17
Enter number in base 8 to convert to base 17 (To go back type /back) 
> 267
Conversion result: AD
Enter number in base 8 to convert to base 17 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 8 20
Enter number in base 8 to convert to base 20 (To go back type /back) 
> 500
Conversion result: G0
Enter number in base 8 to convert to base 20 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 8 23
Enter number in base 8 to convert to base 23 (To go back type /back) 
> 1063
Conversion result: 11B
Enter number in base 8 to convert to base 23 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 8 26
Enter number in base 8 to convert to base 26 (To go back type /back) 
> 57
Conversion result: 1L
Enter number in base 8 to convert to base 26 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 8 29
Enter number in base 8 to convert to base 29 (To go back type /back) 
> 705
Conversion result: FI
Enter number in base 8 to convert to base 29 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 8 32
Enter number in base 8 to convert to base 32 (To go back type /back) 
> 254
Conversion result: 5C
Enter number in base 8 to convert to base 32 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 8 35
Enter number in base 8 to convert to base 35 (To go back type /back) 
> 455
Conversion result: 8L
Enter number in base 8 to convert to base 35 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 11 2
Enter number in base 11 to convert to base 2 (To go back type /back) 
> 143
Conversion result: 10101000
Enter number in base 11 to convert to base 2 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 11 5
Enter number in base 11 to convert to base 5 (To go back type /back) 
> 123
Conversion result: 1041
Enter number in base 11 to convert to base 5 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 11 8
Enter number in base 11 to convert to base 8 (To go back type /back) 
> 451
Conversion result: 1034
Enter number in base 11 to convert to base 8 (To go back type /back) 
> /back
Enter two numbers in format: {source base} {target base} (To quit type /exit) 
> 11 14
Enter number in base 11 to convert to base 14 (To go back type /back) 
> 272
Conversion result: 18D
Enter number in base 11 to convert to base 14 (To go back type /back) 
> /back
Enter two numbers in forma

数字格式异常来自这行代码：

decimalNumber += (elementHolder[j].toString().toBigInteger() * Math.pow(sourceBase.toDouble(), i.toDouble()).toInt().toBigInteger())

Answer 1

您可以通过 try-catch 字符串转换来避免 convertNumberToDecimal 函数中的错误：

fun convertNumberToDecimal(numberToConvert: String, sourceBase: Int): BigInteger { 
    var finalValue = ""
    var elementHolder = (numberToConvert).toMutableList()
    var i = elementHolder.size - 1
    var j = 0
    var decimalNumber = 0.toBigInteger()
    while (j != elementHolder.size) {
        try {
          if (elementHolder[j].toString().toUpperCase() in alphabet) {
            elementHolder[j] = (10 + alphabet.indexOf(elementHolder[j].toString())).toChar()
            println(elementHolder[j])
          }
          decimalNumber += (elementHolder[j].toString().toBigInteger() * Math.pow(sourceBase.toDouble(), i.toDouble()).toInt().toBigInteger())
        } catch (e: NumberFormatException) { }
      j++
      i--
    }
    return decimalNumber
  }

但是，鉴于您的程序结构，我认为该错误可能与输入错误有关。
通过拆分输入字符串（第 splitter = choice.split(" ") 行），您没有考虑包含多个空格的字符串。
在这种情况下，将向函数传递一个空字符串，这将引发异常。
您可以通过过滤输入的字符串来防止错误：

splitter = choice.split(" ").filter { it != "" }
if (splitter.size != 2) {
    // Malformed string
    exitProcess(0)
}
sourceBase = splitter[0].toInt()
targetBase = splitter[1].toInt()

我得到一个 Int 值应该去的字符串

I am getting a String where an Int value should go

error-handling

android

data-conversion

kotlin