update java/ch00 - ch05 with README's and updated libraries.

bgruenba · bgruenba · commit 9bdd67532ac2 · 2025-09-21T12:54:07.000-07:00
diff --git a/cs/ch01/README.md b/cs/ch01/README.md
@@ -1,13 +1,13 @@
 # Test-Driven Development - C# - Chapter 01
 
-This solution contains a code for Chapter 1 of the book ["Test-Driven Development By Example" by 
+This solution contains code for Chapter 1 of the book ["Test-Driven Development By Example" by 
 Kent Beck](https://a.co/d/1sr05eT). The code is written in C# and uses the NUnit testing framework for the tests.
 
 For information on how to set up the repository, please see the [README in the ch00](../ch00/README.md) folder.
 
 ## Chapter 1 - The Multi-Currency Money Example
 Kent starts this chapter with the process you should follow for TDD:
-1. Quicky add a test.
+1. Quickly add a test.
 2. Run all tests and see the new one fail.
 3. Make a little change.
 4. Run all tests and see them all pass.
diff --git a/java/ch00/README.md b/java/ch00/README.md
@@ -1,7 +1,7 @@
 # Test-Driven Development - Java - Introduction and Base Solution
 
 This folder contains a base solution for the book ["Test-Driven Development By Example" by 
-Kent Beck](https://a.co/d/1sr05eT). The code is written in C# and uses the NUnit testing framework for the tests. 
+Kent Beck](https://a.co/d/1sr05eT). The code is written in Java and uses the JUnit testing framework for the tests. 
 I use this solution as the starting point for each chapter from the book.
 
 **To be clear:** The README's in these folders do not contain the content of the chapters. They just contain a summary 
diff --git a/java/ch01/README.md b/java/ch01/README.md
@@ -1,13 +1,13 @@
-# Test-Driven Development - C# - Chapter 01
+# Test-Driven Development - Java - Chapter 01
 
-This solution contains a code for Chapter 1 of the book ["Test-Driven Development By Example" by 
-Kent Beck](https://a.co/d/1sr05eT). The code is written in C# and uses the NUnit testing framework for the tests.
+This solution contains code for Chapter 1 of the book ["Test-Driven Development By Example" by 
+Kent Beck](https://a.co/d/1sr05eT). The code is written in Java and uses the JUnit testing framework for the tests.
 
 For information on how to set up the repository, please see the [README in the ch00](../ch00/README.md) folder.
 
 ## Chapter 1 - The Multi-Currency Money Example
 Kent starts this chapter with the process you should follow for TDD:
-1. Quicky add a test.
+1. Quickly add a test.
 2. Run all tests and see the new one fail.
 3. Make a little change.
 4. Run all tests and see them all pass.
@@ -17,7 +17,7 @@ He then starts out with a TODO list:
 - [ ] \$5 + 10 CHF = $10 if rate is 2:1
 - [ ] \$5 * 2 = $10
 
-These TODO's are then added into the Money.Tests DollarTest class and we write the tests from there.
+These TODO's are then added into the DollarTest class and we write the tests from there.
 By the end of the chapter, that list has grown to this, and only the second item has been completed:
 - [ ] \$5 + 10 CHF = $10 if rate is 2:1
 - [x] \$5 * 2 = $10
@@ -55,7 +55,7 @@ found that when I diverged from the book, large sections became unnecessary. I m
 as the concepts of TDD that each chapter introduces are more important than the implementation.
 
 ### A note about TODO comments in the code
-JetBrains Rider has a TODO window that shows all the TODO comments in the code and I use it extensively in real world 
+JetBrains IntelliJ has a TODO window that shows all the TODO comments in the code and I use it extensively in real world 
 code. I normally delete the TODO comments when I finish the task, but in this case I have left them in to show the
 progression of the chapter and I have marked them as "- DONE" when they are completed.
 
@@ -68,10 +68,11 @@ Another thing to note is that when I am working on a user story, the TODO commen
 tracking system (ADO or Jira) and I delete the TODO comments when I finish the task.
 
 ## Last Update
-I try and keep this code up to date with the latest versions. I generally wait until a new version of .NET SDK is 
-released and I only update it for Long Term Support (LTS)versions. .NET 8 is the latest LTS version as of this writing.
+I try and keep this code up to date with the latest versions. I generally wait until a new version of the JDK or Maven is 
+released and I only update it for major versions. JDK 25 is the latest version as of this writing, and the POM is set to
+use JDK 25 and JUnit 5.13.4.
 
 This repository was last updated in September 2025.
-- .NET SDK version 8
-- NUnit version 4.4.0
-- JetBrains Rider version 2025.2.2
+- Java JDK version 25
+- JUnit version 5.13.4
+- JetBrains IntelliJ IDEA Ultimate version 2025.2.2
diff --git a/java/ch01/src/main/java/com/thesoftwaregorilla/tdd/money/Dollar.java b/java/ch01/src/main/java/com/thesoftwaregorilla/tdd/money/Dollar.java
@@ -3,7 +3,7 @@
 public class Dollar {
     int amount;
 
-    public Dollar(int amount) {
+    Dollar(int amount) {
         this.amount = amount;
     }
 
diff --git a/java/ch01/src/test/java/com/thesoftwaregorilla/tdd/money/DollarTest.java b/java/ch01/src/test/java/com/thesoftwaregorilla/tdd/money/DollarTest.java
@@ -3,9 +3,14 @@
 import org.junit.jupiter.api.Test;
 import static org.junit.jupiter.api.Assertions.*;
 
+//TODO: $5 + 10 CHF = $10 if rate is 2:1
+//TODO: $5 * 2 = $10 - DONE 
+//TODO: Make "amount" private
+//TODO: Dollar side-effects?
+//TODO: Money rounding?
 
 public class DollarTest {
-
+    
     @Test
     public void testConstruction() {
         Dollar five = new Dollar(5);
diff --git a/java/ch02/README.md b/java/ch02/README.md
@@ -1,7 +1,7 @@
-# Test-Driven Development - C# - Chapter 02
+# Test-Driven Development - Java - Chapter 02
 
 This solution contains a code for Chapter 2 of the book ["Test-Driven Development By Example" by 
-Kent Beck](https://a.co/d/1sr05eT). The code is written in C# and uses the NUnit testing framework for the tests. 
+Kent Beck](https://a.co/d/1sr05eT). The code is written in Java and uses the JUnit testing framework for the tests. 
 
 For information on how to set up the repository, please see the [README in the ch00](../ch00/README.md) folder.
 
@@ -19,13 +19,13 @@ easily understood, maintained, and tested so that any changes can be made with c
 
 ### Key points from the chapter
 Kent introduces the concept of the Value Object pattern. In the Chapter 2 implementation, when the `times()` method is 
-called, the value of `Amount` is changed, hence the title of the chapter - Degenerate Objects. He walks us through how
+called, the value of `amount` is changed, hence the title of the chapter - Degenerate Objects. He walks us through how
 he fixes this by returning an immutable value object. The idea is that the `Dollar` object should never change its state. 
 Instead, a new object should be returned with the new state.
 
-There's a key issue with the implementation in Chapter 2, though. The `Amount` member is public and settable. As I
-explained in the [README for Chapter 1](../ch01/README.md), in C# I would normally implement this as a read-only 
-property (in Java, it would be a getter only) , but I have kept it as a public member to stay true to the book until 
+There's a key issue with the implementation in Chapter 2, though. The `amount` member is public and settable. As I
+explained in the [README for Chapter 1](../ch01/README.md), in Java I would normally implement this as a read-only 
+property with a getter only, but I have kept it as a public member to stay true to the book until 
 we make it private in Chapter 4.
 
 Kent also introduces the three strategies for getting to green:
@@ -42,10 +42,11 @@ By the end of the chapter, the TODO list looks like this:
 - [ ] Money rounding?
 
 ## Last Update
-I try and keep this code up to date with the latest versions. I generally wait until a new version of .NET SDK is 
-released and I only update it for Long Term Support (LTS)versions. .NET 8 is the latest LTS version as of this writing.
+I try and keep this code up to date with the latest versions. I generally wait until a new version of the JDK or Maven is 
+released and I only update it for major versions. JDK 25 is the latest version as of this writing, and the POM is set to
+use JDK 25 and JUnit 5.13.4.
 
 This repository was last updated in September 2025.
-- .NET SDK version 8
-- NUnit version 4.4.0
-- JetBrains Rider version 2025.2.2
+- Java JDK version 25
+- JUnit version 5.13.4
+- JetBrains IntelliJ IDEA Ultimate version 2025.2.2
diff --git a/java/ch02/src/main/java/com/thesoftwaregorilla/tdd/money/Dollar.java b/java/ch02/src/main/java/com/thesoftwaregorilla/tdd/money/Dollar.java
@@ -3,7 +3,7 @@
 public class Dollar {
     int amount;
 
-    public Dollar(int amount) {
+    Dollar(int amount) {
         this.amount = amount;
     }
 
diff --git a/java/ch02/src/test/java/com/thesoftwaregorilla/tdd/money/DollarTest.java b/java/ch02/src/test/java/com/thesoftwaregorilla/tdd/money/DollarTest.java
@@ -3,6 +3,11 @@
 import org.junit.jupiter.api.Test;
 import static org.junit.jupiter.api.Assertions.*;
 
+//TODO: $5 + 10 CHF = $10 if rate is 2:1
+//TODO: $5 * 2 = $10 - DONE 
+//TODO: Make "amount" private
+//TODO: Dollar side-effects? - DONE
+//TODO: Money rounding?
 
 public class DollarTest {
 
diff --git a/java/ch03/README.md b/java/ch03/README.md
@@ -1,7 +1,7 @@
-# Test-Driven Development - C# - Chapter 03
+# Test-Driven Development - Java - Chapter 03
 
 This solution contains a code for Chapter 3 of the book ["Test-Driven Development By Example" by 
-Kent Beck](https://a.co/d/1sr05eT). The code is written in C# and uses the NUnit testing framework for the tests. 
+Kent Beck](https://a.co/d/1sr05eT). The code is written in Java and uses the JUnit testing framework for the tests. 
 
 For information on how to set up the repository, please see the [README in the ch00](../ch00/README.md) folder.
 
@@ -11,8 +11,8 @@ Martin Fowler has a good article on the [Value Object pattern](https://martinfow
 worth reading that describes the pattern in more detail. He also has a book called [Patterns of Enterprise Application
 Architecture](https://a.co/d/bDrbiQw) that describes the pattern in more detail. There's also a reasonably good [Wikipedia
 article](https://en.wikipedia.org/wiki/Value_object) that gives examples in several languages, including C#, Java & Python.
-If I were implementing this in the real world, I would probably use a `record` in C# as they are immutable by default and
-implement value equality.
+If I were implementing this in the real world, I would probably use a `record` in Java as they are immutable by default 
+and implement value equality.
 
 ### Triangulation
 Kent introduces the concept of triangulation in this chapter. The idea is that you write three tests that cover the same 
@@ -36,10 +36,11 @@ By the end of the chapter, the TODO list looks like this:
 
 
 ## Last Update
-I try and keep this code up to date with the latest versions. I generally wait until a new version of .NET SDK is 
-released and I only update it for Long Term Support (LTS)versions. .NET 8 is the latest LTS version as of this writing.
+I try and keep this code up to date with the latest versions. I generally wait until a new version of the JDK or Maven is 
+released and I only update it for major versions. JDK 25 is the latest version as of this writing, and the POM is set to
+use JDK 25 and JUnit 5.13.4.
 
 This repository was last updated in September 2025.
-- .NET SDK version 8
-- NUnit version 4.4.0
-- JetBrains Rider version 2025.2.2
+- Java JDK version 25
+- JUnit version 5.13.4
+- JetBrains IntelliJ IDEA Ultimate version 2025.2.2
diff --git a/java/ch03/src/main/java/com/thesoftwaregorilla/tdd/money/Dollar.java b/java/ch03/src/main/java/com/thesoftwaregorilla/tdd/money/Dollar.java
@@ -3,7 +3,7 @@
 public class Dollar {
     int amount;
 
-    public Dollar(int amount) {
+    Dollar(int amount) {
         this.amount = amount;
     }
 
@@ -12,7 +12,6 @@ public Dollar times(int multiplier) {
     }
 
     public boolean equals(Object object) {
-        Dollar dollar = (Dollar) object;
-        return amount == dollar.amount;
+        return object instanceof Dollar dollar && this.amount == dollar.amount;
     }
 }
diff --git a/java/ch03/src/test/java/com/thesoftwaregorilla/tdd/money/DollarTest.java b/java/ch03/src/test/java/com/thesoftwaregorilla/tdd/money/DollarTest.java
@@ -3,6 +3,15 @@
 import org.junit.jupiter.api.Test;
 import static org.junit.jupiter.api.Assertions.*;
 
+//TODO: $5 + 10 CHF = $10 if rate is 2:1
+//TODO: $5 * 2 = $10 - DONE 
+//TODO: Make "amount" private
+//TODO: Dollar side-effects? - DONE
+//TODO: Money rounding?
+//TODO: equals() -DONE
+//TODO: hashCode()
+//TODO: Equal null
+//TODO: Equal object
 
 public class DollarTest {
 
diff --git a/java/ch04/README.md b/java/ch04/README.md
@@ -1,25 +1,30 @@
-# Test-Driven Development - C# - Chapter 04
+# Test-Driven Development - Java - Chapter 04
 
-This solution contains a code for Chapter 4 of the book ["Test-Driven Development By Example" by 
-Kent Beck](https://a.co/d/1sr05eT). The code is written in C# and uses the NUnit testing framework for the tests. 
+This solution contains code for Chapter 4 of the book ["Test-Driven Development By Example" by 
+Kent Beck](https://a.co/d/1sr05eT). The code is written in Java and uses the JUnit testing framework for the tests. 
 
 For information on how to set up the repository, please see the [README in the ch00](../ch00/README.md) folder.
 
 ## Chapter 4 - Privacy
 I think this chapter points out a key aspect of TDD that is often overlooked. Thge tests you write should read like you
 are describing the behavior of the system. In other words, the tests themselves are a form of documentation that 
-describes the intent of the code. The refactor of the `TestMultiplication` test leads to a more readable test
+describes the intent of the code. The refactor of the `testMultiplication` test leads to a more readable test
 that makes the intent much clearer. 
 
 Put another way, the tests are as important to write clearly as the production code is.
 
-The main change to the Dollar class in this chapter is to make the `Amount` member private. 
+The main change to the Dollar class in this chapter is to make the `amount` member private. 
 
-Something the book does not address about this change is that the `TestConstruction()` test no longer compiles as it is
-trying to access a private member. The solution is to either delete the equality test in the `TestConstruction()` test 
-or do an `Is.EqualTo(new Dollar(5))` comparison. I chose to do the latter because I always want my constructor to be
-tested for its values too. Again, I would probably have implemented this as a `record` in C# as it would have been
-immutable by default and implemented value equality, but I have stuck with the book's implementation.
+Something the book does not address about this change is that the `testConstruction()` test no longer compiles as it is
+trying to access a private member. The solution is to either delete the `assertEquals(5, five.getAmount())` equality test 
+in the `testConstruction()` test or do an `assertEquals(new Dollar(5))` comparison. I chose to do the former because 
+I always want my constructor to be tested for its values. 
+
+This is not the same as what I did in the C# version of this code. In C#, I made the `amount` member private and had
+the equality test in `testConstruction()` assert against a new `Dollar(5)` object.
+
+Again, I would probably have implemented this as a `record` in Java as it would have been immutable by default and 
+implemented value equality, but I have stuck with the book's implementation.
 
 ### TODO list at the end of the chapter
 By the end of the chapter, the TODO list looks like this:
@@ -35,10 +40,11 @@ By the end of the chapter, the TODO list looks like this:
 
 
 ## Last Update
-I try and keep this code up to date with the latest versions. I generally wait until a new version of .NET SDK is 
-released and I only update it for Long Term Support (LTS)versions. .NET 8 is the latest LTS version as of this writing.
+I try and keep this code up to date with the latest versions. I generally wait until a new version of the JDK or Maven is 
+released and I only update it for major versions. JDK 25 is the latest version as of this writing, and the POM is set to
+use JDK 25 and JUnit 5.13.4.
 
 This repository was last updated in September 2025.
-- .NET SDK version 8
-- NUnit version 4.4.0
-- JetBrains Rider version 2025.2.2
+- Java JDK version 25
+- JUnit version 5.13.4
+- JetBrains IntelliJ IDEA Ultimate version 2025.2.2
diff --git a/java/ch04/src/main/java/com/thesoftwaregorilla/tdd/money/Dollar.java b/java/ch04/src/main/java/com/thesoftwaregorilla/tdd/money/Dollar.java
@@ -3,7 +3,7 @@
 public class Dollar {
     private final int amount;
 
-    public Dollar(int amount) {
+    Dollar(int amount) {
         this.amount = amount;
     }
 
@@ -12,8 +12,7 @@ public Dollar times(int multiplier) {
     }
 
     public boolean equals(Object object) {
-        Dollar dollar = (Dollar) object;
-        return amount == dollar.amount;
+        return object instanceof Dollar dollar && this.amount == dollar.amount;
     }
 
     // See my note in the DollarTest class. I added a getter for amount because I had a constructor test.
diff --git a/java/ch04/src/test/java/com/thesoftwaregorilla/tdd/money/DollarTest.java b/java/ch04/src/test/java/com/thesoftwaregorilla/tdd/money/DollarTest.java
@@ -3,6 +3,15 @@
 import org.junit.jupiter.api.Test;
 import static org.junit.jupiter.api.Assertions.*;
 
+//TODO: $5 + 10 CHF = $10 if rate is 2:1
+//TODO: $5 * 2 = $10 - DONE 
+//TODO: Make "amount" private
+//TODO: Dollar side-effects? - DONE
+//TODO: Money rounding?
+//TODO: equals() -DONE
+//TODO: hashCode()
+//TODO: Equal null
+//TODO: Equal object
 
 public class DollarTest {
 
diff --git a/java/ch05/README.md b/java/ch05/README.md
@@ -1,7 +1,7 @@
-# Test-Driven Development - C# - Chapter 05
+# Test-Driven Development - Java - Chapter 05
 
-This solution contains a code for Chapter 5 of the book ["Test-Driven Development By Example" by 
-Kent Beck](https://a.co/d/1sr05eT). The code is written in C# and uses the NUnit testing framework for the tests. 
+This solution contains code for Chapter 5 of the book ["Test-Driven Development By Example" by 
+Kent Beck](https://a.co/d/1sr05eT). The code is written in Java and uses the JUnit testing framework for the tests. 
 
 For information on how to set up the repository, please see the [README in the ch00](../ch00/README.md) folder.
 
@@ -29,10 +29,11 @@ By the end of the chapter, the TODO list looks like this:
 - [ ] Common Times
 
 ## Last Update
-I try and keep this code up to date with the latest versions. I generally wait until a new version of .NET SDK is 
-released and I only update it for Long Term Support (LTS)versions. .NET 8 is the latest LTS version as of this writing.
+I try and keep this code up to date with the latest versions. I generally wait until a new version of the JDK or Maven is 
+released and I only update it for major versions. JDK 25 is the latest version as of this writing, and the POM is set to
+use JDK 25 and JUnit 5.13.4.
 
 This repository was last updated in September 2025.
-- .NET SDK version 8
-- NUnit version 4.4.0
-- JetBrains Rider version 2025.2.2
+- Java JDK version 25
+- JUnit version 5.13.4
+- JetBrains IntelliJ IDEA Ultimate version 2025.2.2
diff --git a/java/ch05/src/main/java/com/thesoftwaregorilla/tdd/money/Dollar.java b/java/ch05/src/main/java/com/thesoftwaregorilla/tdd/money/Dollar.java
@@ -3,7 +3,7 @@
 public class Dollar {
     private final int amount;
 
-    public Dollar(int amount) {
+    Dollar(int amount) {
         this.amount = amount;
     }
 
@@ -12,8 +12,7 @@ public Dollar times(int multiplier) {
     }
 
     public boolean equals(Object object) {
-        Dollar dollar = (Dollar) object;
-        return amount == dollar.amount;
+        return object instanceof Dollar dollar && this.amount == dollar.amount;
     }
 
     // See my note in the DollarTest class. I added a getter for amount because I had a constructor test.
diff --git a/java/ch05/src/main/java/com/thesoftwaregorilla/tdd/money/Franc.java b/java/ch05/src/main/java/com/thesoftwaregorilla/tdd/money/Franc.java
diff --git a/java/ch05/src/test/java/com/thesoftwaregorilla/tdd/money/DollarTest.java b/java/ch05/src/test/java/com/thesoftwaregorilla/tdd/money/DollarTest.java

Original file line number	Diff line number	Diff line change
`@@ -3,7 +3,7 @@`
`3`	`3`	`public class Dollar {`
`4`	`4`	`int amount;`
`5`	`5`
`6`		`- public Dollar(int amount) {`
	`6`	`+ Dollar(int amount) {`
`7`	`7`	`this.amount = amount;`
`8`	`8`	`}`
`9`	`9`