我有以下 Scala 代码(从 Java 移植而来):
import scala.util.control.Breaks._
object Main {
def pascal(col: Int, row: Int): Int = {
if(col > row) throw new Exception("Coloumn out of bound");
else if (col == 0 || col == row) 1;
else pascal(col - 1, row - 1) + pascal(col, row - 1);
}
def balance(chars: List[Char]): Boolean = {
val string: String = chars.toString()
if (string.length() == 0) true;
else if(stringContains(")", string) == false && stringContains("(", string) == false) true;
else if(stringContains(")", string) ^ stringContains("(", string)) false;
else if(getFirstPosition("(", string) > getFirstPosition(")", string)) false;
else if(getLastPosition("(", string) > getLastPosition(")", string)) false;
else if(getCount("(", string) != getCount(")", string)) false;
var positionOfFirstOpeningBracket = getFirstPosition("(", string);
var openingBracketOccurences = 1; //we already know that at the first position there is an opening bracket so we are incrementing it right away with 1 and skipping the firstPosition variable in the loop
var closingBracketOccurrences = 0;
var positionOfClosingBracket = 0;
breakable {
for(i <- positionOfFirstOpeningBracket + 1 until string.length()) {
if (string.charAt(i) == ("(".toCharArray())(0)) {
openingBracketOccurences += 1;
}
else if(string.charAt(i) == (")".toCharArray())(0) ) {
closingBracketOccurrences += 1;
}
if(openingBracketOccurences - closingBracketOccurrences == 0) { //this is an important part of the algorithm. if the string is balanced and at the current iteration opening=closing that means we know the bounds of our current brackets.
positionOfClosingBracket = i; // this is the position of the closing bracket
break;
}
}
}
val insideBrackets: String = string.substring(positionOfFirstOpeningBracket + 1, positionOfClosingBracket)
balance(insideBrackets.toList) && balance( string.substring(positionOfClosingBracket + 1, string.length()).toList)
def getFirstPosition(character: String, pool: String): Int =
{
for(i <- 0 until pool.length()) {
if (pool.charAt(i) == (character.toCharArray())(0)) {
i;
}
}
-1;
}
def getLastPosition(character: String, pool: String): Int =
{
for(i <- pool.length() - 1 to 0 by -1) {
if (pool.charAt(i) == (character.toCharArray())(0)) {
i;
}
}
-1;
}
//checks if a string contains a specific character
def stringContains(needle: String, pool: String): Boolean = {
for(i <- 0 until pool.length()) {
if(pool.charAt(i) == (needle.toCharArray())(0)) true;
}
false;
}
//gets the count of occurrences of a character in a string
def getCount(character: String, pool: String) = {
var count = 0;
for ( i <- 0 until pool.length()) {
if(pool.charAt(i) == (character.toCharArray())(0)) count += 1;
}
count;
}
}
}
问题是 Scala IDE(Scaal 2.10.1 的最新版本)在第 78 行(上面有一个闭合括号)给出了以下错误:“类型不匹配;找到单元,预期布尔值”。我真的无法理解实际问题是什么。警告没有给出错误可能在哪里的任何信息。