diff --git a/Doc/Sd1/LanguageFundamentals/languageFundamentals.xml b/Doc/Sd1/LanguageFundamentals/languageFundamentals.xml
index 89e528411f48eeb3896a11b4658084fca186fc1c..602fae1a6faa9be093e5c4827e315f374a0b05d2 100644
--- a/Doc/Sd1/LanguageFundamentals/languageFundamentals.xml
+++ b/Doc/Sd1/LanguageFundamentals/languageFundamentals.xml
@@ -7215,19 +7215,73 @@ age = age + 2; <emphasis role="red">// Error: Incompatible types.</emphasis>
age += 200;</programlisting>
+ <para>So why is <code language="java">age += 2</code> perfectly
+ legal on contrary to <code language="java">age = age + 2</code>
+ ?</para>
+
<tip>
- <para>Consider <xref
- linkend="sd1_fig_noBinaryPlusByteByte"/>.</para>
+ <para>Consider <xref linkend="sd1_fig_noBinaryPlusByteByte"/>
+ and <link
+ xlink:href="https://docs.oracle.com/javase/specs/jls/se19/html/jls-15.html#jls-15.26.2">Compound
+ Assignment Operators</link>.</para>
</tip>
</question>
<answer>
- <para>According to <xref
+ <para>The<link
+ xlink:href="https://docs.oracle.com/javase/specs/jls/se19/html/index.html">
+ Java® Language Specification SE 19 Edition</link> offers a
+ definition in its <link
+ xlink:href="https://docs.oracle.com/javase/specs/jls/se19/html/jls-15.html#jls-15.26.2">Compound
+ Assignment Operators</link> section:</para>
+
+ <blockquote>
+ <para>A compound assignment expression of the form E1 op= E2
+ is equivalent to E1 = (T) ((E1) op (E2)), where T is the type
+ of E1, except that E1 is evaluated only once</para>
+ </blockquote>
+
+ <para>We provide an example illustrating this rather condensed
+ statement:</para>
+
+ <programlisting language="none">double d = 4.5;
+byte i = 3;
+
+ <emphasis role="red">i</emphasis> <emphasis role="red">+</emphasis>= <emphasis
+ role="red">d</emphasis> ;
+// <emphasis role="red">E1</emphasis> <emphasis role="red">op</emphasis>= <emphasis
+ role="red">E2</emphasis></programlisting>
+
+ <para>We thus link:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para><code>i</code> to <code>E1</code></para>
+ </listitem>
+
+ <listitem>
+ <para>the <code>+</code> operator to <code>op</code></para>
+ </listitem>
+
+ <listitem>
+ <para><code>d</code> to <code>E2</code></para>
+ </listitem>
+ </itemizedlist>
+
+ <para> Our variable <code language="java">i</code> aka
+ <code>E1</code> is of type <code language="java">int</code>. T
+ being <code>E1</code>'s type the expression<code> E1 = (T) ((E1)
+ op (E2))</code> hence translates to:</para>
+
+ <programlisting language="java">i = (int)(i + d);</programlisting>
+
+ <para>Back to our original example: According to <xref
linkend="sd1_fig_noBinaryPlusByteByte"/> the arithmetic <code
language="java">+</code> operator acting any two non-long values
will always return a result of type <code
language="java">int</code>. The expression <code
- language="java">age + 2</code> is thus of type <code
+ language="java">age + 2</code> (The literal 2 is of type <code
+ language="java">int</code> anyway) is thus of type <code
language="java">int</code> and therefore requires a cast when
being assigned to our variable <code language="java">age</code>
of type <code language="java">byte</code>:</para>
@@ -7241,7 +7295,7 @@ age = (byte)(age + 2);</programlisting>
defined as <code language="java">final</code> the value of the
expression <code language="java">age + 2</code> is not being
known at compile time. Adding <code
- language="java">final</code> allows for compile time
+ language="java">final</code> would allow for compile time
evaluation and thus assignment to a second variable of type
<code language="java">byte</code> without requiring a
cast:</para>
@@ -7251,10 +7305,9 @@ age = (byte)(age + 2);</programlisting>
byte gettingOlder = age + 2; // o.K. without cast: age + 2 can be evaluated at compile time.</programlisting>
</note>
- <para>On contrary the operator <code language="java">+=</code>
- will accept any right hand integer value (even of type <code
- language="java">long</code>!) thereby possibly cycling through
- the range of byte values e.g.:</para>
+ <para>On contrary regarding the <code language="java">age +=
+ 2</code> expression the equivalent is age = (byte)(age +
+ 2):</para>
<informaltable border="1">
<tr>
diff --git a/Klausuren/Sd1/2021summer/Exam/src/main/java/de/hdm_stuttgart/mi/sd1/task2/LengthUnitCalculator.java b/Klausuren/Sd1/2021summer/Exam/src/main/java/de/hdm_stuttgart/mi/sd1/task2/LengthUnitCalculator.java
index 2654b2b5e5555dda0f7e0939efcc85c37f015584..74edb4f15734745a4b37dee283210ffa0a46c2c1 100644
--- a/Klausuren/Sd1/2021summer/Exam/src/main/java/de/hdm_stuttgart/mi/sd1/task2/LengthUnitCalculator.java
+++ b/Klausuren/Sd1/2021summer/Exam/src/main/java/de/hdm_stuttgart/mi/sd1/task2/LengthUnitCalculator.java
@@ -113,5 +113,20 @@ package de.hdm_stuttgart.mi.sd1.task2;
* </section>
*/
public class LengthUnitCalculator {
- // TODO: implement me
+
+ double length;
+ Unit unit = null;
+ void setLength(final double length) {
+ this.length = length;
+ }
+
+ void setUnit(final Unit unit ) {
+ if (null != unit) {
+
+ }
+
+ this.unit = unit;
+ }
+
+
}
diff --git a/Klausuren/Sd1/2021summer/Exam/src/main/java/de/hdm_stuttgart/mi/sd1/task2/Unit.java b/Klausuren/Sd1/2021summer/Exam/src/main/java/de/hdm_stuttgart/mi/sd1/task2/Unit.java
index d9be29c19886457567190eb4aa60a01aa4cfe9cd..f21b5af7d8616c56e873d7db139866c6a474cd53 100644
--- a/Klausuren/Sd1/2021summer/Exam/src/main/java/de/hdm_stuttgart/mi/sd1/task2/Unit.java
+++ b/Klausuren/Sd1/2021summer/Exam/src/main/java/de/hdm_stuttgart/mi/sd1/task2/Unit.java
@@ -7,18 +7,25 @@ public enum Unit {
/**
* <p>SI metric length 1 meter (m)</p>
*/
- METER,
+ METER(1.0),
/**
* <p>Inch: Imperial length defined as 0.0254m</p>
*/
- INCH,
+ INCH(0.0254),
/**
* <p>Imperial mile defined as 1609.344m</p>
*/
- MILE_IMPERIAL,
+ MILE_IMPERIAL(1609.344),
/**
* <p>Nautical mile defined as 1852m.</p>
*/
- MILE_NAUTICAL
+ MILE_NAUTICAL(1852.);
+
+ Unit(final double lengthInMeter) {
+ this.lengthInMeter = lengthInMeter;
+ }
+
+
+ final private double lengthInMeter;
}