| import java.util.ArrayList; |
| import java.util.List; |
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| public class StringCalculator { |
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| public int add(String input) { |
| if (input == null || input.isEmpty()) { |
| return 0; |
| } |
| String delimiters = ",|\n"; |
| String body = input; |
| if (input.startsWith("//")) { |
| int nl = input.indexOf('\n'); |
| if (nl < 0) { |
| throw new IllegalArgumentException("missing newline after delimiter"); |
| } |
| String custom = input.substring(2, nl); |
| delimiters = java.util.regex.Pattern.quote(custom); |
| body = input.substring(nl + 1); |
| } |
| int sum = 0; |
| List<Integer> negatives = new ArrayList<>(); |
| for (String token : body.split(delimiters)) { |
| if (token.isBlank()) { |
| throw new IllegalArgumentException("empty number"); |
| } |
| int value = Integer.parseInt(token.trim()); |
| if (value < 0) { |
| negatives.add(value); |
| } else if (value <= 1000) { |
| sum += value; |
| } |
| } |
| if (!negatives.isEmpty()) { |
| StringBuilder sb = new StringBuilder("negatives not allowed: "); |
| for (int i = 0; i < negatives.size(); i++) { |
| if (i > 0) { |
| sb.append(", "); |
| } |
| sb.append(negatives.get(i)); |
| } |
| throw new IllegalArgumentException(sb.toString()); |
| } |
| return sum; |
| } |
| } |
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