Day 3 break 4

Questions.txt

@@ -662,3 +662,35 @@ D) the code compiles if the following is added at point x
 E) the code compiles if the following is added at line n1
 non-sealed abstract class Z implements X permits Q {}
 final class Q extends Z {}
+
+
+Q) Given, rooted on the base of the classpath:
+---file: localization/MyResources.properties
+name=Fred
+-----------------------------------------------
+---file: localization/MyResources_de.properties
+name=Helmut
+-----------------------------------------------
+and:
+
+    Locale.setDefault(Locale.FRENCH);
+    ResourceBundle bundle = PropertyResourceBundle.getBundle(
+        "MyResources");
+    System.out.println("Name is " + bundle.getString("name"));
+
+What is the result?
+A) Name is Helmut
+B) Name is Fred
+C) Name is null
+D) an exception is thrown
+E) compilation fails
+
+Q)  Given:
+  StringBuilder sb1 = new StringBuilder("Hello");
+  StringBuilder sb2 = sb1;
+  sb1 = null;
+
+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

src/main/java/localization/TryThis.java

@@ -0,0 +1,15 @@
+package localization;
+
+import java.util.Locale;
+import java.util.PropertyResourceBundle;
+import java.util.ResourceBundle;
+
+public class TryThis {
+  public static void main(String[] args) {
+    Locale.setDefault(Locale.FRENCH);
+    ResourceBundle bundle = PropertyResourceBundle.getBundle(
+        "localization.MyResources");
+    System.out.println("Name is " + bundle.getString("name"));
+
+  }
+}

src/main/java/sealedtypes/Ex1.java

@@ -1,15 +1,30 @@
 package sealedtypes;
 
-interface Transporter {
+// IF, but only if, all types in this sealed type hierarchy
+// are in the same source file, then permits may be omitted.
+// I believe the intention is to simplify development
+//sealed interface Transporter /*permits Truck, Car, Bicycle*/ {
+// If running (but also compiler observes this) under Module System
+// (JPMS) elements of the hierarchy can be in the same module but
+// different packages. IF NOT under JPMS, all elements in the hierarchy
+// MUST BE IN THE SAME PACKAGE
+sealed interface Transporter permits Truck, Car, Bicycle {
 }
 
-class Truck implements Transporter {
+sealed class Truck implements Transporter permits BoxVan {
 }
 
-class Car implements Transporter {
+// lose control of children here
+non-sealed class BoxVan extends Truck {}
+
+final class Car implements Transporter {
 }
 
-//class Bicycle implements Transporter {}
+// records are implicitly final!
+// enums are not "final" but they control their child types
+// if any exist, they must be anonymous/nested types
+// records can implement interfaces, but cannot extend anything explicit
+record Bicycle() implements Transporter {}
 
 public class Ex1 {
   public static void main(String[] args) {

src/main/resources/localization/MyResources.properties

@@ -0,0 +1 @@
+name=Fred

src/main/resources/localization/MyResources_de.properties

@@ -0,0 +1 @@
+name=Helmut