String Calculator

Project Description

The String Calculator is a simple terminal-based Java program that can evaluate mathematical expressions provided as strings. It supports various features such as custom delimiters, handling new lines, and ignoring numbers larger than 1000. This project is a great exercise for beginners to practice string manipulation, exception handling, and test-driven development (TDD) in Java. This project also includes comprehensive tests to validate the functionality and ensure the requirements are met.

Features

Programming language: Java;

1. Basic Addition: The add method can add numbers separated by commas.
   • Example: "1,2,5" will return 8.
2. Handling New Lines: The add method can handle new lines in the input.
   • Example: "1\n,2,3" will return 6.
3. Custom Delimiters: The add method supports custom delimiters specified at the beginning of the string.
   • Format: "//[delimiter]\n[numbers]"
   • Example: "//;\n1;3;4" will return 8.
4. Negative Numbers: Calling add with a negative number will throw an exception with a message listing the negative numbers.
   • Example: "1,-2,3" will throw an exception: "Negatives not allowed: [-2]".
5. Ignoring Large Numbers: Numbers larger than 1000 are ignored.
   • Example: "2,1001" will return 2.
6. Arbitrary Length Delimiters: Custom delimiters can be of arbitrary length.
   • Example: "//***\n1***2***3" will return 6.
7. Multiple Delimiters: The add method supports multiple delimiters.
   • Example: "//$,@\n1$2@3" will return 6.

The goal of the program:

1. Create a simple String calculator with a method "int Add(string numbers)": a. The numbers in the string are separated by a comma. b. Empty strings should return 0. c. The return type should be an integer. d. Example input: “1,2,5”—expected result: “8.” e. Write tests to prove your input validates.

2. Change the Add method to handle new lines in the input format: a. Example: “1\n,2,3” - Result: “6” b. Example 2: “1,\n2,4”—Result: “7”

3. Support a custom delimiter: a. The beginning of your string will now contain a small control code that lets you set a custom delimiter. b. Format: “//[delimiter]\n[delimiter separated numbers]” c. Example: “//;\n1;3;4” - Result: 8 d. In the above you can see that following the double forward slash we set a semicolon, followed by a new line. We then use that delimiter to split our numbers. e. e. Other examples i. “//$\n1$2$3” - Result: 6 ii. “//@\n2@3@8” - Result: 13

4. Calling add with a negative number should throw an exception: “Negatives not allowed.” The exception should list the number(s) that caused the exception

   Bonus:

5. Numbers larger than 1000 should be ignored. a. Example “2,1001”—Result: 2

6. Delimiters can be arbitrary length a. “//***\n1***2***3” - Result 6

7. Allow for multiple delimiters a. “//$,@\n1$2@3” - Result 6

8. Combine 2 and 3 bonus questions. Allow multiple delimiters of arbitrary length.

Tests

The String Calculator project includes comprehensive tests to validate the functionality and ensure the requirements are met. These tests cover various scenarios such as handling empty strings, custom delimiters, negative numbers, and more. To run the tests, use your preferred Java IDE or a build tool like Maven or Gradle.

Example Test

public class StringCalculatorTest {

   @Test
   public final void whenEmptyStringIsUsedThenReturnValueIs0() {
      assertEquals (0, StringCalculator.add (""));
   }
}

Usage

To use the String Calculator, call the add method with a string containing the numbers you want to add. The method will return the sum of the numbers. You can specify custom delimiters and handle new lines as described in the features section.

Educational Value: It can serve as a good example for learning and practicing TDD, string parsing, and basic arithmetic operations in Java.

Code Reuse: The code can be reused or extended for other projects that require string-based calculations.

Example Code

public class Main {
   public static void main(String[] args) {
      final int result = StringCalculator.add ("//$,@\n1$2@3");
      System.out.println ("Result: " + result); // Output: Result: 6
   }
}

Installation Instructions

1. Download the project.
2. Open the project in your preferred Java IDE (e.g., IntelliJ IDEA, Eclipse).
3. Compile and run the Main class to see the String Calculator in action.
4. Compile and run the StringCalculatorTest class to see the tests in action and validate the functionality.