Final!

Questions.txt

@@ -693,4 +693,31 @@ Q)  Given:
 Which is true?
 A) sb1 is unreferenced and eligible for GC
 B) sb1 and sb2 are unreferenced and eligible for GC
-C) No objects are eligible for GC
+C) No objects are eligible for GC
+
+Q) Given:
+  StringBuilder sb1 = new StringBuilder("Hello");
+  StringBuilder sb2 = new StringBuilder("World");
+  sb1 = null;
+  sb2 = sb1;
+
+Which is true?
+A) Object containing "Hello" is unreferenced and eligible for GC
+B) Object containing "World" is unreferenced and eligible for GC
+C) No objects are eligible for GC
+
+Q) Given:
+static String doStuff(String s) {
+  s = new String("Hello");
+  return new String(s);
+}
+
+and:
+  String y = doStuff("Hello");
+  // line n1
+
+how many String objects are eligible for GC at line n1
+A) 0
+B) 1
+C) 2
+D) 3

mod.one/pom.xml

@@ -0,0 +1,20 @@
+<?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>
+        <groupId>org.example</groupId>
+        <artifactId>SafariJava17CertStudy</artifactId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>mod.one</artifactId>
+
+    <properties>
+        <maven.compiler.source>17</maven.compiler.source>
+        <maven.compiler.target>17</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+</project>

mod.one/src/main/java/anotherpackage/PackageLevel.java

@@ -0,0 +1,5 @@
+package anotherpackage;
+
+public class PackageLevel {
+  static String msg = "package access";
+}

mod.one/src/main/java/module-info.java

@@ -0,0 +1,7 @@
+/*open*/ module mod.one {
+//  requires java.base; // implicitly required
+
+  exports service to mod.two, bad;
+//  opens service to mod.two, bad;
+  opens service;
+}

mod.one/src/main/java/service/MyValues.java

@@ -0,0 +1,6 @@
+package service;
+
+public class MyValues {
+  public static String message = "Hello";
+  private static String secretMessage = "Whisper";
+}

mod.two/pom.xml

@@ -0,0 +1,20 @@
+<?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>
+        <groupId>org.example</groupId>
+        <artifactId>SafariJava17CertStudy</artifactId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+
+    <artifactId>mod.two</artifactId>
+
+    <properties>
+        <maven.compiler.source>17</maven.compiler.source>
+        <maven.compiler.target>17</maven.compiler.target>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+</project>

mod.two/src/main/java/anotherpackage/HackIt.java

@@ -0,0 +1,7 @@
+package anotherpackage;
+
+//public class HackIt {
+//  public static String getIt() {
+//    return anotherpackage.PackageLevel.msg;
+//  }
+//}

mod.two/src/main/java/client/MyClient.java

@@ -0,0 +1,19 @@
+package client;
+
+//import anotherpackage.HackIt;
+
+import java.lang.reflect.Field;
+
+public class MyClient {
+  public static void main(String[] args) throws Throwable {
+    System.out.println(service.MyValues.message);
+//    System.out.println(service.MyValues.secretMessage);
+    Class<?> cl = service.MyValues.class;
+    Field f = cl.getDeclaredField("secretMessage");
+    f.setAccessible(true);
+    Object secret = f.get(null);
+    System.out.println(secret);
+    // JPMS prohibits "split packages"
+//    System.out.println(HackIt.getIt());
+  }
+}

mod.two/src/main/java/module-info.java

@@ -0,0 +1,3 @@
+module mod.two {
+  requires mod.one;
+}

pom.xml

@@ -7,6 +7,11 @@
     <groupId>org.example</groupId>
     <artifactId>SafariJava17CertStudy</artifactId>
     <version>1.0-SNAPSHOT</version>
+    <packaging>pom</packaging>
+    <modules>
+        <module>mod.one</module>
+        <module>mod.two</module>
+    </modules>
 
     <properties>
         <maven.compiler.source>17</maven.compiler.source>