feat: Adds lesson_04 content

lesson_04/README.md

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+# Lesson 04
+
+## Homework
+
+1. Read CC 12.
+1. Read article entitled [3 Questions That Will Make You A Phenomenal Rubber Duck][article-link]
+1. Complete the [Expression Calculator](#expression-calculator) exercise
+
+## Expression Calculator
+
+For this assignment, you will need to implement the functions and logic required to calculate a mathematical expression. After implementing the `add`, `divide`, and `multiply` functions, you will combine these functions to compute the final result.
+
+1. Update the code in the [ExpressionCalculator.java][calculator-file] file.
+2. To check your work, you can run the application using the first command below and run the tests using the second one.
+```bash
+./gradlew run --console=plain
+./gradlew test
+```
+3. As usual, make sure that you format your code and run the check command before creating your pull request.
+```bash
+./gradlew spotlessApply
+./gradlew check
+```
+4. You must only submit changes to the `ExpressionCalculator.java` file to receive full credit.
+
+[article-link]: https://blog.danslimmon.com/2024/01/18/3-questions-that-will-make-you-a-phenomenal-rubber-duck/
+[calculator-file]: ./expression/expression_app/src/main/java/com/codedifferently/lesson4/ExpressionCalculator.java 

lesson_04/expression/.gitattributes

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+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# Linux start script should use lf
+/gradlew        text eol=lf
+
+# These are Windows script files and should use crlf
+*.bat           text eol=crlf
+

lesson_04/expression/.gitignore

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+# Ignore Gradle project-specific cache directory
+.gradle
+
+# Ignore Gradle build output directory
+build

lesson_04/expression/.project

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+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>lesson_04</name>
+	<comment>Project quiz created by Buildship.</comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.buildship.core.gradleprojectbuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.buildship.core.gradleprojectnature</nature>
+	</natures>
+	<filteredResources>
+		<filter>
+			<id>1708474157606</id>
+			<name></name>
+			<type>30</type>
+			<matcher>
+				<id>org.eclipse.core.resources.regexFilterMatcher</id>
+				<arguments>node_modules|\.git|__CREATED_BY_JAVA_LANGUAGE_SERVER__</arguments>
+			</matcher>
+		</filter>
+	</filteredResources>
+</projectDescription>

lesson_04/expression/.settings/org.eclipse.buildship.core.prefs

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+arguments=--init-script /Users/anthonymays/.local/share/nvim/mason/packages/jdtls/config_mac/org.eclipse.osgi/54/0/.cp/gradle/init/init.gradle
+auto.sync=false
+build.scans.enabled=false
+connection.gradle.distribution=GRADLE_DISTRIBUTION(WRAPPER)
+connection.project.dir=
+eclipse.preferences.version=1
+gradle.user.home=
+java.home=/Library/Java/JavaVirtualMachines/temurin-17.jdk/Contents/Home
+jvm.arguments=
+offline.mode=false
+override.workspace.settings=true
+show.console.view=true
+show.executions.view=true

lesson_04/expression/expression_app/.classpath

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+<?xml version="1.0" encoding="UTF-8"?>
+<classpath>
+	<classpathentry kind="src" output="bin/main" path="src/main/java">
+		<attributes>
+			<attribute name="gradle_scope" value="main"/>
+			<attribute name="gradle_used_by_scope" value="main,test"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="src" output="bin/test" path="src/test/java">
+		<attributes>
+			<attribute name="gradle_scope" value="test"/>
+			<attribute name="gradle_used_by_scope" value="test"/>
+			<attribute name="test" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-17/"/>
+	<classpathentry kind="con" path="org.eclipse.buildship.core.gradleclasspathcontainer"/>
+	<classpathentry kind="src" path="/instructional-lib">
+		<attributes>
+			<attribute name="without_test_code" value="true"/>
+		</attributes>
+	</classpathentry>
+	<classpathentry kind="output" path="bin/default"/>
+</classpath>

lesson_04/expression/expression_app/.project

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+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>expression_app</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+		<buildCommand>
+			<name>org.eclipse.buildship.core.gradleprojectbuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+		<nature>org.eclipse.buildship.core.gradleprojectnature</nature>
+	</natures>
+	<filteredResources>
+		<filter>
+			<id>1</id>
+			<name></name>
+			<type>30</type>
+			<matcher>
+				<id>org.eclipse.core.resources.regexFilterMatcher</id>
+				<arguments>node_modules|\.git|__CREATED_BY_JAVA_LANGUAGE_SERVER__</arguments>
+			</matcher>
+		</filter>
+	</filteredResources>
+</projectDescription>

lesson_04/expression/expression_app/.settings/org.eclipse.buildship.core.prefs

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+connection.project.dir=..
+eclipse.preferences.version=1

lesson_04/expression/expression_app/.settings/org.eclipse.jdt.core.prefs

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+eclipse.preferences.version=1
+org.eclipse.jdt.core.classpath.outputOverlappingAnotherSource=ignore
+org.eclipse.jdt.core.compiler.annotation.missingNonNullByDefaultAnnotation=ignore
+org.eclipse.jdt.core.compiler.annotation.nonnull=org.eclipse.jdt.annotation.NonNull
+org.eclipse.jdt.core.compiler.annotation.nonnullbydefault=org.eclipse.jdt.annotation.NonNullByDefault
+org.eclipse.jdt.core.compiler.annotation.nullable=org.eclipse.jdt.annotation.Nullable
+org.eclipse.jdt.core.compiler.annotation.nullanalysis=disabled
+org.eclipse.jdt.core.compiler.codegen.inlineJsrBytecode=enabled
+org.eclipse.jdt.core.compiler.codegen.targetPlatform=17
+org.eclipse.jdt.core.compiler.codegen.unusedLocal=preserve
+org.eclipse.jdt.core.compiler.compliance=17
+org.eclipse.jdt.core.compiler.debug.lineNumber=generate
+org.eclipse.jdt.core.compiler.debug.localVariable=generate
+org.eclipse.jdt.core.compiler.debug.sourceFile=generate
+org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
+org.eclipse.jdt.core.compiler.problem.enumIdentifier=error
+org.eclipse.jdt.core.compiler.problem.nullAnnotationInferenceConflict=error
+org.eclipse.jdt.core.compiler.problem.nullReference=warning
+org.eclipse.jdt.core.compiler.problem.nullSpecViolation=error
+org.eclipse.jdt.core.compiler.problem.potentialNullReference=ignore
+org.eclipse.jdt.core.compiler.problem.syntacticNullAnalysisForFields=disabled
+org.eclipse.jdt.core.compiler.source=17

lesson_04/expression/expression_app/build.gradle.kts

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+plugins {
+    // Apply the application plugin to add support for building a CLI application in Java.
+    application
+    eclipse
+    id("com.diffplug.spotless") version "6.25.0"
+	  id("org.springframework.boot") version "3.2.2"
+}
+
+apply(plugin = "io.spring.dependency-management")
+
+repositories {
+    // Use Maven Central for resolving dependencies.
+    mavenCentral()
+}
+
+dependencies {
+    // Use JUnit Jupiter for testing.
+    testImplementation("com.codedifferently.instructional:instructional-lib")
+    testImplementation("org.junit.jupiter:junit-jupiter:5.9.1")
+    testImplementation("org.springframework.boot:spring-boot-starter-test")
+    testImplementation("org.assertj:assertj-core:3.25.1")
+    testImplementation("at.favre.lib:bcrypt:0.10.2")
+
+    // This dependency is used by the application.
+    implementation("com.codedifferently.instructional:instructional-lib")
+    implementation("com.google.guava:guava:31.1-jre")
+    implementation("org.projectlombok:lombok:1.18.30")
+    implementation("org.springframework.boot:spring-boot-starter")
+}
+
+application {
+    // Define the main class for the application.
+    mainClass.set("com.codedifferently.lesson4.Lesson4")
+}
+
+tasks.named<JavaExec>("run") {
+    standardInput = System.`in`
+}
+
+tasks.named<Test>("test") {
+    // Use JUnit Platform for unit tests.
+    useJUnitPlatform()
+}
+
+
+configure<com.diffplug.gradle.spotless.SpotlessExtension> {
+
+  format("misc", {
+    // define the files to apply `misc` to
+    target("*.gradle", ".gitattributes", ".gitignore")
+
+    // define the steps to apply to those files
+    trimTrailingWhitespace()
+    indentWithTabs() // or spaces. Takes an integer argument if you don't like 4
+    endWithNewline()
+  })
+
+  java {
+    // don't need to set target, it is inferred from java
+
+    // apply a specific flavor of google-java-format
+    googleJavaFormat()
+    // fix formatting of type annotations
+    formatAnnotations()
+  }
+}

lesson_04/expression/expression_app/src/main/java/com/codedifferently/lesson4/ExpressionCalculator.java

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+package com.codedifferently.lesson4;
+
+public class ExpressionCalculator {
+  /**
+   * Returns the calculation of ((a + b) * c) / d^e
+   *
+   * @param a
+   * @param b
+   * @return
+   */
+  public double calculate(double a, double b, double c, double d, double e) {
+    // Implement your code here to return the correct value.
+    return 0d;
+  }
+
+  public double pow(double base, double exponent) {
+    return Math.pow(base, exponent);
+  }
+}

lesson_04/expression/expression_app/src/main/java/com/codedifferently/lesson4/Lesson4.java

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+package com.codedifferently.lesson4;
+
+import java.util.Scanner;
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@SpringBootApplication(scanBasePackages = "com.codedifferently")
+public class Lesson4 implements CommandLineRunner {
+
+  public static void main(String[] args) {
+    // To test, use `./gradlew run --console=plain`
+    var application = new SpringApplication(Lesson4.class);
+    application.run(args);
+  }
+
+  public void run(String... args) {
+    // Use Scanner to get input from the user.
+    var scanner = new Scanner(System.in);
+
+    System.out.print("\nEnter a value for variable 'a': ");
+    int a = scanner.nextInt();
+
+    System.out.print("Enter a value for variable 'b': ");
+    int b = scanner.nextInt();
+
+    System.out.print("Enter a value for variable 'c': ");
+    int c = scanner.nextInt();
+
+    System.out.print("Enter a value for variable 'd': ");
+    int d = scanner.nextInt();
+
+    System.out.print("Enter a value for variable 'e': ");
+    int e = scanner.nextInt();
+
+    // Close the scanner to avoid memory leaks.
+    scanner.close();
+
+    System.out.println(
+        String.format("\nNow computing the value of ((%s + %s) * %s) / %s^%s", a, b, c, d, e));
+
+    var calculator = new ExpressionCalculator();
+    double result = calculator.calculate(a, b, c, d, e);
+
+    System.out.println(String.format("The result is: %s", result));
+  }
+}

lesson_04/expression/expression_app/src/test/java/com/codedifferently/lesson4/Lesson4Test.java

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+package com.codedifferently.lesson4;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.lang.reflect.Method;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+class Lesson4Test {
+
+  private ExpressionCalculator calculator;
+
+  @BeforeEach
+  void setUp() {
+    calculator = new ExpressionCalculator();
+  }
+
+  @Test
+  void testCalculate() {
+    // Arrange
+    var a = 1;
+    var b = 2;
+    var c = 3;
+    var d = 4;
+    var e = 5;
+    var expected = ((a + b) * c) / Math.pow(d, e);
+
+    // Act
+    double actual = calculator.calculate(a, b, c, d, e);
+
+    // Assert
+    assertThat(actual).isEqualTo(expected);
+  }
+
+  @Test
+  void testAdd_works() throws Exception {
+    // Arrange
+    Method method = calculator.getClass().getDeclaredMethod("add", double.class, double.class);
+
+    // Act
+    var result = (double) method.invoke(calculator, 1, 2);
+
+    // Assert
+    assertThat(result).isEqualTo(3);
+  }
+
+  @Test
+  void testMultipy_works() throws Exception {
+    // Arrange
+    Method method = calculator.getClass().getDeclaredMethod("multiply", double.class, double.class);
+
+    // Act
+    var result = (double) method.invoke(calculator, 1, 2);
+
+    // Assert
+    assertThat(result).isEqualTo(2);
+  }
+
+  @Test
+  void testDivide_works() throws Exception {
+    // Arrange
+    Method method = calculator.getClass().getDeclaredMethod("divide", double.class, double.class);
+
+    // Act
+    var result = (double) method.invoke(calculator, 1, 2);
+
+    // Assert
+    assertThat(result).isEqualTo(0.5d);
+  }
+
+  @Test
+  void testPow_works() throws Exception {
+    // Arrange
+    Method method = calculator.getClass().getDeclaredMethod("pow", double.class, double.class);
+
+    // Act
+    var result = (double) method.invoke(calculator, 2, 3);
+
+    // Assert
+    assertThat(result).isEqualTo(8);
+  }
+}

lesson_04/expression/gradle/wrapper/gradle-wrapper.properties

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+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.0.2-bin.zip
+networkTimeout=10000
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists