refactor!: reorganize project into separate modules for independent testing

- Convert single-module project to multi-module Maven structure
- Create exception-handling module for practical exception handling exercises
- Create custom-exceptions module for custom exception creation tasks
- Move existing tests and source files to appropriate modules
- Update README with module-specific instructions and testing commands
- Update parent pom.xml to use pom packaging with module declarations

BREAKING CHANGE: Project structure changed from single module to multi-module, requiring updated build and test commands

Author: Genyus

README.md

@@ -5,83 +5,146 @@
 [![Maven Dependency Manager](https://img.shields.io/badge/dependency%20manager-Maven-AA215A.svg?style=for-the-badge)][3]
 
 The goal of this exercise is to practise:
-- Creating custom exceptions
 - Handling exceptions
+- Creating custom exceptions
 
-For the exercises below, we've provided the starter project above.
+This project is organized into two modules that can be compiled and tested independently:
 
-## :pushpin: Exceptions
+- **exception-handling**: Practical exception handling exercises
+- **custom-exceptions**: Custom exception creation and file processing exercises
 
-### Question 1
+### Running Tests
 
-Is the following code legal?
+To run all tests across both modules:
 
-```java
-try {
+```shell
+./mvnw clean test
+```
 
-} finally {
+To test a specific module:
 
-}
+```shell
+./mvnw clean test -pl exception-handling
+./mvnw clean test -pl custom-exceptions
 ```
 
-### Question 2
+## :pushpin: Exception Handling
+
+Create a class called `ExceptionExercises` in the `exception-handling/src/main/java/com/cbfacademy` directory with the following methods that demonstrate proper exception handling techniques. Each method should handle specific exceptions gracefully and return appropriate values.
+
+Using the [Java Exception Handling documentation][4] as a guide, implement the methods described below. In each method, replace `throw new RuntimeException("Not implemented")` with your code.
+
+### Safe Division
+
+Create a method that performs division while handling potential arithmetic exceptions:
 
-What exception types can be caught by the following handler?
 ```java
-catch (Exception e) {
-    
+public Double divide(Double numerator, Double denominator) {
+    // TODO: Implement this method to divide the numerator by the denominator
+    // - return the result of the division
+    // - if the denominator is 0, catch the ArithmeticException and return null
+    // - if either parameter is null, return null
+    throw new RuntimeException("Not implemented");
 }
 ```
 
-What is wrong with using this type of exception handler?
+### Safe List Access
 
-### Question 3
+Create a method that safely accesses list elements:
 
-Is there anything wrong with the following exception handler as written? Will this code compile?
+```java
+public Integer getListElement(List<Integer> list, int index) {
+    // TODO: Implement this method to return the element at the specified index
+    // - return the element at the given index
+    // - if the index is out of bounds, catch IndexOutOfBoundsException and return -1
+    // - if the list is null, return -1
+    throw new RuntimeException("Not implemented");
+}
+```
+
+### Safe String to Integer Conversion
+
+Create a method that safely converts strings to integers:
 
 ```java
-try {
+public Integer convertToInteger(String numberString) {
+    // TODO: Implement this method to convert a string to an integer
+    // - return the integer value of the string
+    // - if the string cannot be converted, catch NumberFormatException and return 0
+    // - if the string is null, return null
+    throw new RuntimeException("Not implemented");
+}
+```
 
-} catch (Exception e) {
+### Safe String Processing
 
-} catch (ArithmeticException a) {
+Create a method that safely processes strings:
 
+```java
+public String getStringLength(String input) {
+    // TODO: Implement this method to return a formatted string with the length
+    // - return "Length: [length]" where [length] is the length of the input string
+    // - if the input is null, catch NullPointerException and return "Length: 0"
+    throw new RuntimeException("Not implemented");
 }
 ```
 
-### Question 4
+### Multiple Exception Handling
+
+Create a method that demonstrates handling multiple types of exceptions:
 
 ```java
-int[] A; 
-A[0] = 0;
+public String processData(List<String> data, int index) {
+    // TODO: Implement this method to process list data
+    // - get the string at the specified index from the list
+    // - convert that string to an integer
+    // - return "Processed: [integer_value]"
+    // - if index is out of bounds, return "Index out of bounds"
+    // - if string conversion fails, return "Invalid number format"
+    // - if the list is null, return "List is null"
+    throw new RuntimeException("Not implemented");
+}
+```
+
+**Example Usage:**
+```java
+ExceptionExercises exercises = new ExceptionExercises();
+
+// Safe division
+Double result1 = exercises.divide(10.0, 2.0);    // Returns 5.0
+Double result2 = exercises.divide(10.0, 0.0);    // Returns null (handles ArithmeticException)
+
+// Safe list access
+List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
+Integer element1 = exercises.getListElement(numbers, 2);    // Returns 3
+Integer element2 = exercises.getListElement(numbers, 10);   // Returns -1 (handles IndexOutOfBoundsException)
+
+// Safe string conversion
+Integer num1 = exercises.convertToInteger("123");     // Returns 123
+Integer num2 = exercises.convertToInteger("abc");     // Returns 0 (handles NumberFormatException)
 ```
 
-The above code produces (choose 1):
+#### :white_check_mark: Verify Your Implementation
 
-- [ ] an error
-- [ ] a checked exception
-- [ ] an unchecked exception
-- [ ] a compile error
-- [ ] no exception
+To verify that your code works as expected, run the provided unit tests.
 
-### Question 5
+In your terminal, ensure that you are in the root directory of this repo, then run the following command:
 
-The JVM starts running your program, but the JVM can't find the Java platform classes. 
-(The Java platform classes reside in classes.zip or rt.jar.)
+```shell
+./mvnw clean test -pl exception-handling
+```
 
-What happens (choose 1):
+Or to run only the ExceptionExercises tests:
 
-- [ ] an error
-- [ ] a checked exception
-- [ ] an unchecked exception
-- [ ] a compile error
-- [ ] no exception
+```shell
+./mvnw clean test -pl exception-handling -Dtest=ExceptionExercisesTest
+```
 
 ## :pushpin: Custom Exceptions
 
-Create a custom (checked) exception class called `FilenameException`.
+Create a custom (checked) exception class called `FilenameException` in the `custom-exceptions/src/main/java/com/cbfacademy` directory.
 
-Create a class called `FileExtension` with the following methods:
+Create a class called `FileExtension` in the same directory with the following methods:
 
 - `boolean check(String filename)`
 - `Map<String, int> map(List<String> filenames)`
@@ -110,16 +173,16 @@ For the following list of file names: `Arrays.asList("App.java", "App.txt", null
 
 To verify that your code works as expected, run the provided unit tests.
 
-In your terminal, ensure that you are in the `java-exceptions` folder, then run the following command:
+In your terminal, ensure that you are in the root directory of this repo, then run the following command:
 
 ```shell
-./mvnw clean test
+./mvnw clean test -pl custom-exceptions
 ```
 
-If you are on Windows, run this command instead:
+Or to run only the FileExtension tests:
 
-```bat
-mvnw clean test
+```shell
+./mvnw clean test -pl custom-exceptions -Dtest=FileExtensionTest
 ```
 
 Your implementation is correct when all tests pass.
@@ -140,4 +203,5 @@ mvnw -q clean compile exec:java
 
 [1]: https://docs.oracle.com/javase/21/docs/api/index.html
 [2]: https://junit.org/junit5/
-[3]: https://maven.apache.org/
+[3]: https://maven.apache.org/
+[4]: https://docs.oracle.com/javase/tutorial/essential/exceptions/

custom-exceptions/pom.xml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <artifactId>java-exceptions</artifactId>
+    <groupId>com.cbfacademy</groupId>
+    <version>1.0.0</version>
+  </parent>
+
+  <groupId>com.cbfacademy</groupId>
+  <artifactId>custom-exceptions</artifactId>
+  <version>1.0.0</version>
+
+  <name>custom-exceptions</name>
+
+  <build>
+    <pluginManagement>
+      <plugins>
+        <plugin>
+          <groupId>org.apache.maven.plugins</groupId>
+          <artifactId>maven-compiler-plugin</artifactId>
+          <configuration>
+            <testExcludes>
+              <!-- <testExclude>**/FileExtensionTest.java</testExclude> -->
+              <!-- <testExclude>**/FilenameExceptionTest.java</testExclude> -->
+            </testExcludes>
+          </configuration>
+        </plugin>
+      </plugins>
+    </pluginManagement>
+  </build>
+</project> 

src/main/java/com/cbfacademy/App.java renamed to custom-exceptions/src/main/java/com/cbfacademy/App.java

@@ -0,0 +1,31 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+  <parent>
+    <artifactId>java-exceptions</artifactId>
+    <groupId>com.cbfacademy</groupId>
+    <version>1.0.0</version>
+  </parent>
+
+  <groupId>com.cbfacademy</groupId>
+  <artifactId>exception-handling</artifactId>
+  <version>1.0.0</version>
+
+  <name>exception-handling</name>
+
+  <build>
+    <pluginManagement>
+      <plugins>
+        <plugin>
+          <groupId>org.apache.maven.plugins</groupId>
+          <artifactId>maven-compiler-plugin</artifactId>
+          <configuration>
+            <testExcludes>
+              <!-- <testExclude>**/ExceptionExercisesTest.java</testExclude> -->
+            </testExcludes>
+          </configuration>
+        </plugin>
+      </plugins>
+    </pluginManagement>
+  </build>
+</project>