feature: align build to Java 11, add test suite, CI, and code-quality fixes

Co-Authored-By: Bobby Nobakht <bobby.nobakht@cognition.ai>

Author: devin-ai-integration[bot]

.github/workflows/build.yml

@@ -0,0 +1,26 @@
+name: build
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up JDK 11
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: '11'
+          cache: maven
+
+      - name: Compile
+        run: mvn -B compile
+
+      - name: Test
+        run: mvn -B test

.gitignore

@@ -1,9 +1,11 @@
 /target
 /local
+dependency-reduced-pom.xml
 
 # Eclipse, Netbeans and IntelliJ files
 /.*
 !.gitignore
+!.github
 /nbproject
 /*.ipr
 /*.iws

README.md

@@ -29,17 +29,18 @@ The source code for all examples can be found in the directory [src/main/java/la
 * Appendix D: Lambdas and JVM bytecode
 We will update the repository as we update the book. Stay tuned!
 
-### Make sure to have JDK8 installed
-The latest binary can be found here: http://www.oracle.com/technetwork/java/javase/overview/java8-2100321.html
+### Make sure to have JDK 11 (or newer) installed
+The 2nd-edition examples use APIs introduced after Java 8 (e.g. `Optional.or`, `Optional.stream`,
+`Collectors.flatMapping`/`filtering`, `Stream.takeWhile`), so the project targets Java 11
+(`maven.compiler.release=11` in `pom.xml`). A JDK 11 or later distribution is required to build.
+You can download a JDK from [Eclipse Temurin (Adoptium)](https://adoptium.net/) or
+[Oracle Java](https://www.oracle.com/java/technologies/downloads/).
 
 $ java -version
 
-java version "1.8.0_05"
-Java(TM) SE Runtime Environment (build 1.8.0_05-b13)
-Java HotSpot(TM) 64-Bit Server VM (build 25.5-b02, mixed mode)
-
-
-You can download a preview version here: https://jdk8.java.net/
+openjdk version "11.0.22" 2024-01-16
+OpenJDK Runtime Environment (build 11.0.22+7)
+OpenJDK 64-Bit Server VM (build 11.0.22+7, mixed mode)
 
 ### Compile/Run the examples
 Using maven:
@@ -55,5 +56,5 @@ Alternatively you can compile the files manually inside the directory src/main/j
 
 You can also import the project in your favorite IDE:
     * In IntelliJ use "File->Open" menu and navigate to the folder where the project resides
-    * In Eclipse use "File->Import->Existing Maven Projects" (also modify "Reduntant super interfaces" to report as Warnings instead of Errors
+    * In Eclipse use "File->Import->Existing Maven Projects" (also modify "Redundant super interfaces" to report as Warnings instead of Errors
     * In Netbeans use "File->Open Project" menu

pom.xml

@@ -10,23 +10,26 @@
 
     <properties>
       <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+      <maven.compiler.release>11</maven.compiler.release>
+      <jmh.version>1.37</jmh.version>
     </properties>
 
   <dependencies>
     <dependency>
       <groupId>org.openjdk.jmh</groupId>
       <artifactId>jmh-core</artifactId>
-      <version>1.17.4</version>
+      <version>${jmh.version}</version>
     </dependency>
     <dependency>
       <groupId>org.openjdk.jmh</groupId>
       <artifactId>jmh-generator-annprocess</artifactId>
-      <version>1.17.4</version>
+      <version>${jmh.version}</version>
     </dependency>
     <dependency>
       <groupId>junit</groupId>
       <artifactId>junit</artifactId>
-      <version>4.11</version>
+      <version>4.13.2</version>
+      <scope>test</scope>
     </dependency>
   </dependencies>
 
@@ -35,15 +38,12 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
-        <version>3.1</version>
-        <configuration>
-          <source>1.9</source>
-          <target>1.9</target>
-        </configuration>
+        <version>3.13.0</version>
       </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-shade-plugin</artifactId>
+        <version>3.5.3</version>
         <executions>
           <execution>
             <phase>package</phase>

src/main/java/lambdasinaction/chap1/FilteringApples.java

@@ -9,26 +9,26 @@ public static void main(String ... args){
 
         List<Apple> inventory = Arrays.asList(new Apple(80,"green"),
                                               new Apple(155, "green"),
-                                              new Apple(120, "red"));	
+                                              new Apple(120, "red"));
 
         // [Apple{color='green', weight=80}, Apple{color='green', weight=155}]
         List<Apple> greenApples = filterApples(inventory, FilteringApples::isGreenApple);
         System.out.println(greenApples);
-        
+
         // [Apple{color='green', weight=155}]
         List<Apple> heavyApples = filterApples(inventory, FilteringApples::isHeavyApple);
         System.out.println(heavyApples);
-        
+
         // [Apple{color='green', weight=80}, Apple{color='green', weight=155}]
         List<Apple> greenApples2 = filterApples(inventory, (Apple a) -> "green".equals(a.getColor()));
         System.out.println(greenApples2);
-        
+
         // [Apple{color='green', weight=155}]
         List<Apple> heavyApples2 = filterApples(inventory, (Apple a) -> a.getWeight() > 150);
         System.out.println(heavyApples2);
-        
+
         // []
-        List<Apple> weirdApples = filterApples(inventory, (Apple a) -> a.getWeight() < 80 || 
+        List<Apple> weirdApples = filterApples(inventory, (Apple a) -> a.getWeight() < 80 ||
                                                                        "brown".equals(a.getColor()));
         System.out.println(weirdApples);
     }
@@ -54,7 +54,7 @@ public static List<Apple> filterHeavyApples(List<Apple> inventory){
     }
 
     public static boolean isGreenApple(Apple apple) {
-        return "green".equals(apple.getColor()); 
+        return "green".equals(apple.getColor());
     }
 
     public static boolean isHeavyApple(Apple apple) {
@@ -69,7 +69,7 @@ public static List<Apple> filterApples(List<Apple> inventory, Predicate<Apple> p
             }
         }
         return result;
-    }       
+    }
 
     public static class Apple {
         private int weight = 0;

src/main/java/lambdasinaction/chap10/ReadPositiveIntParam.java

@@ -1,32 +1,11 @@
 package lambdasinaction.chap10;
 
-import org.junit.*;
-
 import java.util.*;
 
 import static java.util.Optional.*;
-import static org.junit.Assert.assertEquals;
 
 public class ReadPositiveIntParam {
 
-    @Test
-    public void testMap() {
-        Properties props = new Properties();
-        props.setProperty("a", "5");
-        props.setProperty("b", "true");
-        props.setProperty("c", "-3");
-
-        assertEquals(5, readDurationImperative(props, "a"));
-        assertEquals(0, readDurationImperative(props, "b"));
-        assertEquals(0, readDurationImperative(props, "c"));
-        assertEquals(0, readDurationImperative(props, "d"));
-
-        assertEquals(5, readDurationWithOptional(props, "a"));
-        assertEquals(0, readDurationWithOptional(props, "b"));
-        assertEquals(0, readDurationWithOptional(props, "c"));
-        assertEquals(0, readDurationWithOptional(props, "d"));
-    }
-
     public static int readDurationImperative(Properties props, String name) {
         String value = props.getProperty(name);
         if (value != null) {

src/main/java/lambdasinaction/chap11/Util.java

@@ -25,20 +25,11 @@ public static void delay() {
 
     public static double format(double number) {
         synchronized (formatter) {
-            return new Double(formatter.format(number));
+            return Double.parseDouble(formatter.format(number));
         }
     }
 
     public static <T> CompletableFuture<List<T>> sequence(List<CompletableFuture<T>> futures) {
-/*
-        CompletableFuture<Void> allDoneFuture =
-                CompletableFuture.allOf(futures.toArray(new CompletableFuture[futures.size()]));
-        return allDoneFuture.thenApply(v ->
-                futures.stream().
-                        map(future -> future.join()).
-                        collect(Collectors.<T>toList())
-        );
-*/
         return CompletableFuture.supplyAsync(() -> futures.stream().
                 map(future -> future.join()).
                 collect(Collectors.<T>toList()));

src/test/java/lambdasinaction/chap1/FilteringApplesTest.java

@@ -0,0 +1,49 @@
+package lambdasinaction.chap1;
+
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import lambdasinaction.chap1.FilteringApples.Apple;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class FilteringApplesTest {
+
+    private final List<Apple> inventory = Arrays.asList(
+            new Apple(80, "green"),
+            new Apple(155, "green"),
+            new Apple(120, "red"));
+
+    @Test
+    public void filterGreenApplesReturnsOnlyGreen() {
+        List<Apple> green = FilteringApples.filterGreenApples(inventory);
+        assertEquals(2, green.size());
+        assertTrue(green.stream().allMatch(a -> "green".equals(a.getColor())));
+    }
+
+    @Test
+    public void filterHeavyApplesReturnsApplesOver150() {
+        List<Apple> heavy = FilteringApples.filterHeavyApples(inventory);
+        assertEquals(1, heavy.size());
+        assertEquals(Integer.valueOf(155), heavy.get(0).getWeight());
+    }
+
+    @Test
+    public void filterApplesWithPredicate() {
+        List<Apple> redApples = FilteringApples.filterApples(inventory, a -> "red".equals(a.getColor()));
+        assertEquals(1, redApples.size());
+        assertEquals("red", redApples.get(0).getColor());
+    }
+
+    @Test
+    public void isGreenAppleAndIsHeavyApple() {
+        assertTrue(FilteringApples.isGreenApple(new Apple(50, "green")));
+        assertFalse(FilteringApples.isGreenApple(new Apple(50, "red")));
+        assertTrue(FilteringApples.isHeavyApple(new Apple(200, "red")));
+        assertFalse(FilteringApples.isHeavyApple(new Apple(100, "red")));
+    }
+}

src/test/java/lambdasinaction/chap10/ReadPositiveIntParamTest.java

@@ -0,0 +1,30 @@
+package lambdasinaction.chap10;
+
+import org.junit.Test;
+
+import java.util.Properties;
+
+import static lambdasinaction.chap10.ReadPositiveIntParam.readDurationImperative;
+import static lambdasinaction.chap10.ReadPositiveIntParam.readDurationWithOptional;
+import static org.junit.Assert.assertEquals;
+
+public class ReadPositiveIntParamTest {
+
+    @Test
+    public void testMap() {
+        Properties props = new Properties();
+        props.setProperty("a", "5");
+        props.setProperty("b", "true");
+        props.setProperty("c", "-3");
+
+        assertEquals(5, readDurationImperative(props, "a"));
+        assertEquals(0, readDurationImperative(props, "b"));
+        assertEquals(0, readDurationImperative(props, "c"));
+        assertEquals(0, readDurationImperative(props, "d"));
+
+        assertEquals(5, readDurationWithOptional(props, "a"));
+        assertEquals(0, readDurationWithOptional(props, "b"));
+        assertEquals(0, readDurationWithOptional(props, "c"));
+        assertEquals(0, readDurationWithOptional(props, "d"));
+    }
+}

src/test/java/lambdasinaction/chap11/UtilTest.java

@@ -0,0 +1,15 @@
+package lambdasinaction.chap11;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class UtilTest {
+
+    @Test
+    public void formatRoundsToTwoDecimals() {
+        assertEquals(3.14, Util.format(3.14159), 0.0001);
+        assertEquals(5.0, Util.format(5.0), 0.0001);
+        assertEquals(2.5, Util.format(2.5), 0.0001);
+    }
+}