Fully functional

Added the String Calculator to Github

StringCalculator/src/session1/StringCalculator.java

@@ -0,0 +1,46 @@
+package session1;
+
+public class StringCalculator {
+	public int add(String numbers) throws CalculateException {
+		// Did we get some input? Good! Lets calculate!
+		if (numbers != "") {
+			
+			// Look for negative numbers
+			if (numbers.contains("-")) {
+				throw new CalculateException("Negatives not allowed");
+			}
+
+			// Do we need another delimiter?
+			if (numbers.contains("//")) {
+				numbers = numbers.replace("\n", "");
+				String delimiter = String.valueOf(numbers.charAt(2));
+				String[] split = numbers.split(delimiter);
+				return Integer.parseInt(split[1]) + Integer.parseInt(split[2]);
+			}
+
+			// Replace all those \n with the standard delimiter
+			numbers = numbers.replace("\n", ",");
+
+			// Two delimiters? We can't have that
+			if (numbers.contains(",,")) {
+				throw new CalculateException("Two separators found.");
+			}
+
+			// A standard delimiter? Go ahead and calculate
+			if (numbers.contains(",")) {
+				String[] split = numbers.split(",");
+				return Integer.parseInt(split[0]) + Integer.parseInt(split[1]);
+			}
+			
+			// No delimiters? OK, you can have your number back them
+			else {
+				return Integer.parseInt(numbers);
+			}
+		}
+
+		// No input? Then I got nothing to do.
+		else {
+			return 0;
+		}
+	}
+}