From d2c71a535080a8c757458c849703ef632f217961 Mon Sep 17 00:00:00 2001
From: Martin Goik <goik@hdm-stuttgart.de>
Date: Mon, 3 Jul 2023 12:47:27 +0200
Subject: [PATCH] Summer 2023 Exam
---
Doc/Sd1/Appendix/Exam/2023/Summer/exam.xml | 255 +++++++++++++++++++++
Doc/Sd1/Appendix/appendix.xml | 3 +
2 files changed, 258 insertions(+)
create mode 100644 Doc/Sd1/Appendix/Exam/2023/Summer/exam.xml
diff --git a/Doc/Sd1/Appendix/Exam/2023/Summer/exam.xml b/Doc/Sd1/Appendix/Exam/2023/Summer/exam.xml
new file mode 100644
index 000000000..f8e04de04
--- /dev/null
+++ b/Doc/Sd1/Appendix/Exam/2023/Summer/exam.xml
@@ -0,0 +1,255 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<section version="5.0" xml:id="sd1_exam_2023_summer" xml:lang="en"
+ xmlns="http://docbook.org/ns/docbook"
+ xmlns:xlink="http://www.w3.org/1999/xlink"
+ xmlns:xila="http://www.w3.org/2001/XInclude/local-attributes"
+ xmlns:xi="http://www.w3.org/2001/XInclude"
+ xmlns:trans="http://docbook.org/ns/transclusion"
+ xmlns:svg="http://www.w3.org/2000/svg"
+ xmlns:m="http://www.w3.org/1998/Math/MathML"
+ xmlns:html="http://www.w3.org/1999/xhtml"
+ xmlns:db="http://docbook.org/ns/docbook">
+ <title>SD1 examination summer 2023</title>
+
+ <section xml:id="sd1_exam_2023_summer_task1">
+ <title>Implementing tasks</title>
+
+ <section xml:id="sd1_exam_2023_summer_task1_preparation">
+ <title>Preparation</title>
+
+ <orderedlist>
+ <listitem>
+ <para>Download and unzip the above file
+ <filename>exam.zip</filename>. You should see a directory
+ »<filename>Exam</filename>« containing a
+ <filename>pom.xml</filename> file.</para>
+ </listitem>
+
+ <listitem>
+ <para>Open this project in your <productname>IDEA</productname> IDE
+ by selecting the <filename>Exam/pom.xml</filename> file.</para>
+ </listitem>
+ </orderedlist>
+ </section>
+
+ <section xml:id="sd1_exam_2023_summer_task1_task">
+ <title>Task</title>
+
+ <qandaset defaultlabel="qanda" xml:id="sd1_exam_2023_summer_task1Qanda">
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>Open the <filename>Readme.md</filename> file in your
+ project's root. It contains all necessary instructions for
+ solving the implementation tasks.</para>
+ </question>
+
+ <answer>
+ <para>Solution see <link
+ xlink:href="https://gitlab.mi.hdm-stuttgart.de/goik/GoikLectures/-/tree/master/Klausuren/Sd1/2023summer/Solve">summer
+ 2023 exam</link>.</para>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+ </section>
+
+ <section xml:id="sd1_exam_2023_summer_task1Caveats">
+ <title>Caveats</title>
+
+ <itemizedlist>
+ <listitem>
+ <para>When approaching end of examination check your input for
+ completeness prior to being automatically logged out by the system.
+ Remember: There is 120 minutes for the examination and another 5
+ minutes to check for completeness.</para>
+ </listitem>
+
+ <listitem>
+ <para>Projects residing just on your local workstation's file system
+ cannot be recovered after finishing the exam.</para>
+ </listitem>
+ </itemizedlist>
+ </section>
+ </section>
+
+ <section xml:id="sd1_exam_2023_summer_task2">
+ <title>switch versus if ... else if ... else</title>
+
+ <qandaset defaultlabel="qanda" xml:id="sd1_exam_2023_summer_task3Qanda">
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>Consider a method
+ <methodname>computeItemCount()</methodname> of following
+ signature:</para>
+
+ <programlisting language="none">static int computeItemCount() {...}</programlisting>
+
+ <para>This method will be called by two different implementations
+ of another method <methodname>getScore()</methodname>:</para>
+
+ <informaltable border="1">
+ <tr>
+ <th>Implementation by <code>switch</code></th>
+
+ <th>Implementation by <code>if ... else if ...
+ else</code></th>
+ </tr>
+
+ <tr>
+ <td valign="top"><programlisting language="java">public static int getScore() {
+
+ switch (computeItemCount()){
+ case 1: return 20;
+ case 3: return 50;
+ default: return 0;
+ }
+}</programlisting></td>
+
+ <td valign="top"><programlisting language="java">public static int getScore() {
+
+ if (1 == computeItemCount()) {
+ return 20;
+ } else if (3 == computeItemCount()) {
+ return 50;
+ } else {
+ return 0;
+ }
+}</programlisting></td>
+ </tr>
+ </informaltable>
+
+ <para>An experienced programmer claims these two implementations
+ possibly return different results when executing
+ <methodname>getScore()</methodname>. Is she right? <emphasis
+ role="red">Explain</emphasis> your answer.</para>
+
+ <tip>
+ <para>Consider possible side effects of calling
+ <methodname>computeItemCount()</methodname> and provide an
+ example.</para>
+ </tip>
+ </question>
+
+ <answer>
+ <para>Consider:</para>
+
+ <programlisting language="java">public class X {
+ private static int itemCount = 2;
+
+ static int computeItemCount() {return itemCount++;}
+ ...
+}</programlisting>
+
+ <para>On a fresh start calling
+ <methodname>computeItemCount()</methodname> for the first time
+ will return the current value 2 of our variable <code
+ language="java">itemCount</code>.</para>
+
+ <para>The <code language="java">switch</code> implementation will
+ match its default and thus return 0.</para>
+
+ <para>On contrary the <code>if ... else if ... else</code>
+ implementation will call
+ <methodname>computeItemCount()</methodname> two times:</para>
+
+ <orderedlist>
+ <listitem>
+ <para>The first if <code>(1 == computeItemCount())</code>
+ fails since 1 != 2. This results in incrementing <code
+ language="java">itemCount</code> by 1 to the new value
+ 3.</para>
+ </listitem>
+
+ <listitem>
+ <para>Now the else if <code language="java">(3 ==
+ computeItemCount())</code> clause succeeds. Thus
+ <methodname>getScore()</methodname> returns 50.</para>
+ </listitem>
+ </orderedlist>
+
+ <para>So the <code language="java">switch</code> statement
+ implementing a jump table differs from <code>if ... else if</code>
+ in definitely calling <code
+ language="java">computeItemCount()</code> only once.</para>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+ </section>
+
+ <section xml:id="sd1_exam_2023_summer_task3">
+ <title>Exception handling</title>
+
+ <qandaset defaultlabel="qanda" xml:id="sd1_exam_2023_summer_task2Qanda">
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>Consider the following snippet:</para>
+
+ <programlisting language="java">Object o = ...;
+int a = ...;
+...
+try {
+ String s = (String) o; // May throw a <link
+ xlink:href="https://freedocs.mi.hdm-stuttgart.de/doc/openjdk-17-doc/api/java.base/java/lang/ClassCastException.html">ClassCastException</link>
+ int c = 4 / a; // May throw an <link
+ xlink:href="https://freedocs.mi.hdm-stuttgart.de/doc/openjdk-17-doc/api/java.base/java/lang/ArithmeticException.html">ArithmeticException</link>
+} catch (<link xlink:href="https://freedocs.mi.hdm-stuttgart.de/doc/openjdk-17-doc/api/java.base/java/lang/ClassCastException.html">ClassCastException</link> e) {
+ System.err.println(e.getMessage());
+} catch (<link xlink:href="https://freedocs.mi.hdm-stuttgart.de/doc/openjdk-17-doc/api/java.base/java/lang/ArithmeticException.html">ArithmeticException</link> e) {
+ System.err.println(e.getMessage());
+}</programlisting>
+
+ <para>Facilitate the above code and <emphasis
+ role="red">explain</emphasis> why your simpler implementation
+ always and under all circumstances produces an identical runtime
+ result.</para>
+
+ <tip>
+ <itemizedlist>
+ <listitem>
+ <para>Both <code language="java">catch</code> clauses
+ contain the same text.</para>
+ </listitem>
+
+ <listitem>
+ <para>Search the inheritance hierarchy for a common ancestor
+ class and consider the <methodname>getMessage()</methodname>
+ method. Where is it actually being defined?</para>
+ </listitem>
+ </itemizedlist>
+ </tip>
+ </question>
+
+ <answer>
+ <para>Both <link
+ xlink:href="https://freedocs.mi.hdm-stuttgart.de/doc/openjdk-17-doc/api/java.base/java/lang/ClassCastException.html">ClassCastException</link>
+ and <link
+ xlink:href="https://freedocs.mi.hdm-stuttgart.de/doc/openjdk-17-doc/api/java.base/java/lang/ArithmeticException.html">ArithmeticException</link>
+ are being derived from their common parent <link
+ xlink:href="https://freedocs.mi.hdm-stuttgart.de/doc/openjdk-17-doc/api/java.base/java/lang/RuntimeException.html">RuntimeException</link>.
+ All three classes share the common <link
+ xlink:href="https://freedocs.mi.hdm-stuttgart.de/doc/openjdk-17-doc/api/java.base/java/lang/Throwable.html">Throwable</link>#<link
+ xlink:href="https://freedocs.mi.hdm-stuttgart.de/doc/openjdk-17-doc/api/java.base/java/lang/Throwable.html#getMessage()">getMessage()</link>
+ method by inheritance without redefining it.</para>
+
+ <para>Our two <code>catch</code> clauses may thus be combined into
+ one:</para>
+
+ <programlisting language="java">...
+try {
+ String s = (String) o; // May throw a <link
+ xlink:href="https://freedocs.mi.hdm-stuttgart.de/doc/openjdk-17-doc/api/java.base/java/lang/ClassCastException.html">ClassCastException</link>
+ int c = 4 / a; // May throw an <link
+ xlink:href="https://freedocs.mi.hdm-stuttgart.de/doc/openjdk-17-doc/api/java.base/java/lang/ArithmeticException.html">ArithmeticException</link>
+} catch (<link xlink:href="https://freedocs.mi.hdm-stuttgart.de/doc/openjdk-17-doc/api/java.base/java/lang/RuntimeException.html">RuntimeException</link> e) { // Common parent class
+ System.err.println(e.getMessage());
+}</programlisting>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+ </section>
+</section>
diff --git a/Doc/Sd1/Appendix/appendix.xml b/Doc/Sd1/Appendix/appendix.xml
index 1d330794b..dfb566eae 100644
--- a/Doc/Sd1/Appendix/appendix.xml
+++ b/Doc/Sd1/Appendix/appendix.xml
@@ -2353,6 +2353,9 @@ Value 2147483645 is not prime.
</listitem>
</orderedlist>
+ <xi:include href="Exam/2023/Summer/exam.xml" xpointer="element(/1)"
+ ns:idfixup="auto"/>
+
<xi:include href="Exam/2022/Winter/exam.xml" xpointer="element(/1)"
ns:idfixup="auto"/>
--
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