From 5d91169d071555dad315ed333a5c83d0ee6ce375 Mon Sep 17 00:00:00 2001
From: Martin Goik <goik@hdm-stuttgart.de>
Date: Sun, 15 Mar 2015 22:08:57 +0100
Subject: [PATCH] data type related exercises
---
Doc/Common/glossary.xml | 70 ++-
Doc/Sd1/class.xml | 3 +-
Doc/Sd1/languageFundamentals.xml | 752 +++++++++++++++++++++++++++++++
Doc/Sd1/steinbruch.xml | 134 ++++++
Doc/lectures.xml | 17 +-
5 files changed, 960 insertions(+), 16 deletions(-)
create mode 100644 Doc/Sd1/languageFundamentals.xml
create mode 100644 Doc/Sd1/steinbruch.xml
diff --git a/Doc/Common/glossary.xml b/Doc/Common/glossary.xml
index e566cf719..56ac475f4 100644
--- a/Doc/Common/glossary.xml
+++ b/Doc/Common/glossary.xml
@@ -36,6 +36,15 @@
</glossdef>
</glossentry>
+ <glossentry xml:id="glo_byte">
+ <glossterm>Byte</glossterm>
+
+ <glossdef>
+ <para xlink:href="http://en.wikipedia.org/wiki/Byte">Unit of
+ information</para>
+ </glossdef>
+ </glossentry>
+
<glossentry xml:id="glo_CSV">
<glossterm><acronym>CSV</acronym></glossterm>
@@ -240,22 +249,41 @@
</glossdef>
</glossentry>
- <glossentry xml:id="glo_Java">
- <glossterm><trademark>Java</trademark></glossterm>
+ <glossentry xml:id="glo_JavaLevel1">
+ <glossterm>Java</glossterm>
<glossdef>
- <para><link
- xlink:href="http://www.oracle.com/us/legal/third-party-trademarks/index.html">The
- Java programming language</link></para>
- </glossdef>
- </glossentry>
+ <glosslist>
+ <glossentry xml:id="glo_Java_integralTypes">
+ <glossterm><code>int</code></glossterm>
- <glossentry xml:id="glo_Javadoc">
- <glossterm><trademark>Javadoc</trademark></glossterm>
+ <glossdef>
+ <para
+ xlink:href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-4.html#jls-4.2.1">Integral
+ Types and Values</para>
+ </glossdef>
+ </glossentry>
- <glossdef>
- <para><link xlink:href="http://en.wikipedia.org/wiki/Javadoc">The Java
- documentation system</link></para>
+ <glossentry xml:id="glo_Java">
+ <glossterm><trademark>Java</trademark></glossterm>
+
+ <glossdef>
+ <para><link
+ xlink:href="http://www.oracle.com/us/legal/third-party-trademarks/index.html">The
+ Java programming language</link></para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry xml:id="glo_Javadoc">
+ <glossterm><trademark>Javadoc</trademark></glossterm>
+
+ <glossdef>
+ <para><link
+ xlink:href="http://en.wikipedia.org/wiki/Javadoc">The Java
+ documentation system</link></para>
+ </glossdef>
+ </glossentry>
+ </glosslist>
</glossdef>
</glossentry>
@@ -421,6 +449,15 @@
</glossdef>
</glossentry>
+ <glossentry xml:id="glo_RGB">
+ <glossterm><acronym>RGB</acronym></glossterm>
+
+ <glossdef>
+ <para xlink:href="http://en.wikipedia.org/wiki/RGB_color_model">RGB
+ color model</para>
+ </glossdef>
+ </glossentry>
+
<glossentry xml:id="glo_SAX">
<glossterm><acronym>SAX</acronym></glossterm>
@@ -477,6 +514,15 @@
</glossdef>
</glossentry>
+ <glossentry xml:id="glo_unicode">
+ <glossterm><acronym>Unicode</acronym></glossterm>
+
+ <glossdef>
+ <para><link xlink:href="http://en.wikipedia.org/wiki/Unicode">The
+ Unicode standard</link></para>
+ </glossdef>
+ </glossentry>
+
<glossentry xml:id="glo_UNIX">
<glossterm><acronym>UNIX</acronym></glossterm>
diff --git a/Doc/Sd1/class.xml b/Doc/Sd1/class.xml
index 36b1ebd5c..3e9efc690 100644
--- a/Doc/Sd1/class.xml
+++ b/Doc/Sd1/class.xml
@@ -7,7 +7,8 @@
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>Lecture 5 - Classes, instances and internal state (20.10)</title>
+ <title>-------------------------------- Classes, instances and internal
+ state (20.10)</title>
<section xml:id="sd1CrabsEnhancePrepare">
<title>Preparations</title>
diff --git a/Doc/Sd1/languageFundamentals.xml b/Doc/Sd1/languageFundamentals.xml
new file mode 100644
index 000000000..fd2e61fc3
--- /dev/null
+++ b/Doc/Sd1/languageFundamentals.xml
@@ -0,0 +1,752 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<chapter version="5.0" xml:id="sw1LanguageFundamental"
+ xmlns="http://docbook.org/ns/docbook"
+ xmlns:xlink="http://www.w3.org/1999/xlink"
+ xmlns:xi="http://www.w3.org/2001/XInclude"
+ 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>Language Fundamentals</title>
+
+ <section xml:id="sw1IntegerLiterals">
+ <title>Integer value literals</title>
+
+ <qandaset defaultlabel="qanda" xml:id="sw1QandaMaxMinInt">
+ <title>An <code>int</code>'s minimum and maximum value</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>A <xref linkend="glo_Java"/> <code>int</code> is internally
+ being represented by 4 <link linkend="glo_byte">bytes</link>.
+ <inlineequation>
+ <m:math display="inline">
+ <m:msub>
+ <m:mi>00000000000000000000000000000101</m:mi>
+
+ <m:mi>2</m:mi>
+ </m:msub>
+ </m:math>
+ </inlineequation> for example represents the decimal value
+ 5.</para>
+
+ <para>In order to represent negative values as well <xref
+ linkend="glo_Java"/> uses <link
+ xlink:href="http://en.wikipedia.org/wiki/Two's_complement#firstHeading">Two's
+ complement</link> representation. We provide some values:</para>
+
+ <table border="1" xml:id="sw1Table4ByteIntegerRepresentation">
+ <caption>4 Byte <link
+ xlink:href="http://en.wikipedia.org/wiki/Two's_complement#firstHeading">Two's
+ complement</link> representation of <code>int</code>
+ values.</caption>
+
+ <tr>
+ <th>Two complement representation</th>
+
+ <th>Decimal representation</th>
+ </tr>
+
+ <tr>
+ <td><code>00000000000000000000000000000000</code></td>
+
+ <td>0</td>
+ </tr>
+
+ <tr>
+ <td><code>01111111111111111111111111111111</code></td>
+
+ <td><inlineequation>
+ <m:math display="inline">
+ <m:mrow>
+ <m:msup>
+ <m:mi>2</m:mi>
+
+ <m:mrow>
+ <m:mi>16</m:mi>
+
+ <m:mo>-</m:mo>
+
+ <m:mi>1</m:mi>
+ </m:mrow>
+ </m:msup>
+
+ <m:mo>-</m:mo>
+
+ <m:mi>1</m:mi>
+ </m:mrow>
+ </m:math>
+ </inlineequation> (Maximum)</td>
+ </tr>
+
+ <tr>
+ <td><code>10000000000000000000000000000000</code></td>
+
+ <td><inlineequation>
+ <m:math display="inline">
+ <m:mrow>
+ <m:mo>-</m:mo>
+
+ <m:msup>
+ <m:mi>2</m:mi>
+
+ <m:mrow>
+ <m:mi>16</m:mi>
+
+ <m:mo>-</m:mo>
+
+ <m:mi>1</m:mi>
+ </m:mrow>
+ </m:msup>
+ </m:mrow>
+ </m:math>
+ </inlineequation> (Minimum)</td>
+ </tr>
+
+ <tr>
+ <td><code>11111111111111111111111111111111</code></td>
+
+ <td>-1</td>
+ </tr>
+ </table>
+
+ <para>Use <link
+ xlink:href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.1"><code>int</code>
+ literals</link> in <link
+ xlink:href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-BinaryNumeral">binary
+ representation</link> like e.g. <code>0B1100</code> in section
+ <quote
+ xlink:href="http://proquest.safaribooksonline.com/9780992133047/toc6_html_2">Literals</quote>
+ in order to write an <code>int</code>'s minimum and maximum
+ possible value to standard output.</para>
+
+ <programlisting language="java"> public static void main(String[] args) {
+
+ int minumum = ... , //TODO: provide values by
+ maximum = ...; // binary int literals
+
+ System.out.println("Minimum:" + minumum);
+ System.out.println("Maximum:" + maximum);
+ }</programlisting>
+ </question>
+
+ <answer>
+ <para>We insert <link
+ xlink:href="http://en.wikipedia.org/wiki/Two's_complement#firstHeading">Two's
+ complement</link> representations of minimum and maximum int
+ values according to <xref
+ linkend="sw1Table4ByteIntegerRepresentation"/>.</para>
+
+ <programlisting language="java">public static void main(String[] args) {
+
+ int minumum = 0B10000000_00000000_00000000_00000000,
+ maximum = 0B01111111_11111111_11111111_11111111;
+
+ System.out.println("Minimum int value:" + minumum);
+ System.out.println("Maximum int value:" + maximum);
+ }</programlisting>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+
+ <section xml:id="sw1SectHexadecimalLiterals">
+ <title>Hexadecimal literals</title>
+
+ <para>Using the decimal system to represent integer values we tend to
+ ignore other important numbering systems. As you may know the <xref
+ linkend="glo_RGB"/> color model uses triplets of numbers to define color
+ value components representing intensities of three base colors
+ <foreignphrase><emphasis role="bold">R</emphasis>ed</foreignphrase>,
+ <foreignphrase><emphasis role="bold">G</emphasis>reen</foreignphrase>
+ and <foreignphrase><emphasis
+ role="bold">B</emphasis>lue</foreignphrase>. The component values range
+ from 0 to 255, the latter defining maximum intensity.</para>
+
+ <para>The color <quote>red</quote> for example is being represented by
+ (255, 0, 0). So the red component has maximum intensity, blue and green
+ are zero.</para>
+
+ <para>It is common to use <link
+ xlink:href="http://www.december.com/html/spec/color16codes.html">hexadecimal
+ in favour of decimal values</link>. Thus the font color
+ <quote>red</quote> in the subsequent HTML example's heading is being
+ represented by <emphasis role="bold">(FF,0,0)</emphasis>:</para>
+
+ <programlisting language="html"><!DOCTYPE html>
+<html xmlns="http://www.w3.org/1999/xhtml">
+ <head>
+ <title>A simple color example</title>
+ </head>
+
+ <body><h1 style="<emphasis role="bold">color: #FF0000;</emphasis>">My heading</h1></body>
+</html></programlisting>
+
+ <qandaset defaultlabel="qanda" xml:id="sw1QandaIntByBinary">
+ <title>Integer values by binary representations</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>Calculate the decimal representation of the hexadecimal
+ value <inlineequation>
+ <m:math display="inline">
+ <m:msub>
+ <m:mi>CO</m:mi>
+
+ <m:mi>16</m:mi>
+ </m:msub>
+ </m:math>
+ </inlineequation>.</para>
+
+ <para>Complete the following code by assigning the hexadecimal
+ value <inlineequation>
+ <m:math display="inline">
+ <m:msub>
+ <m:mi>CO</m:mi>
+
+ <m:mi>16</m:mi>
+ </m:msub>
+ </m:math>
+ </inlineequation> (The <quote>silver</quote> color all three
+ component's intensity in <uri
+ xlink:href="http://www.december.com/html/spec/color16codes.html">http://www.december.com/html/spec/color16codes.html</uri>)
+ to get the output in decimal representation.</para>
+
+ <programlisting language="java">public static void main(String[] args) {
+ short intensity = ...;
+
+ System.out.println(intensity);
+}</programlisting>
+
+ <tip>
+ <para>You may want to consider <quote
+ xlink:href="http://proquest.safaribooksonline.com/9780992133047/toc6_html_2">Literals</quote>
+ to find out how to represent integer values in hexadecimal
+ notation.</para>
+ </tip>
+ </question>
+
+ <answer>
+ <para>The solution is straightforward:</para>
+
+ <programlisting language="java"> public static void main(String[] args) {
+
+ short intensity = 0xC0;
+
+ System.out.println(intensity);
+ }</programlisting>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+
+ <qandaset defaultlabel="qanda" xml:id="sw1QandaIntLimitShort">
+ <title>Testing the limits, part 2 (Difficult)</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>A careful programmer is worried whether a short variable
+ is <emphasis role="bold">always</emphasis> large enough to hold
+ color intensity values ranging from 0 to 255. Give an answer
+ being based on the <link
+ xlink:href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-4.html#jls-4.2.1">specification</link>.</para>
+
+ <para>The programmer tries to adopt the <link
+ linkend="sw1QandaMaxMinInt">related int example</link> and
+ adopts it accordingly:</para>
+
+ <programlisting language="java">short minumum = 0B10000000_00000000,
+ maximum = 0B01111111_11111111;
+
+System.out.println("Minimum short value:" + minumum);
+System.out.println("Maximum short value:" + maximum);
+</programlisting>
+
+ <para>Our programmer is baffled since:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>The first assignment <code language="java">minumum =
+ 0B10000000_00000000</code> is being flagged as a compile
+ time error:</para>
+
+ <para><computeroutput>Type mismatch: cannot convert from int
+ to short</computeroutput></para>
+ </listitem>
+
+ <listitem>
+ <para>On contrary the second assignment <code
+ language="java">maximum = 0B01111111_11111111</code> gets
+ smoothly accepted.</para>
+ </listitem>
+ </itemizedlist>
+
+ <tip>
+ <para>Which integer literals types do exist according to the
+ <xref linkend="glo_Java"/> <link
+ xlink:href="http://docs.oracle.com/javase/specs/jls/se8/html/jls-3.html#jls-3.10.1">standard</link>?</para>
+ </tip>
+ </question>
+
+ <answer>
+ <para>The programmer's question is basically easy to answer:
+ Since <code>short</code> variables are being represented by to
+ bytes their range is <inlineequation>
+ <m:math display="inline">
+ <m:mrow>
+ <m:mo>[</m:mo>
+
+ <m:mrow>
+ <m:mrow>
+ <m:mo>-</m:mo>
+
+ <m:msup>
+ <m:mi>2</m:mi>
+
+ <m:mi>15</m:mi>
+ </m:msup>
+ </m:mrow>
+
+ <m:mo>,</m:mo>
+
+ <m:mrow>
+ <m:msup>
+ <m:mi>2</m:mi>
+
+ <m:mi>15</m:mi>
+ </m:msup>
+
+ <m:mo>-</m:mo>
+
+ <m:mi>1</m:mi>
+ </m:mrow>
+ </m:mrow>
+
+ <m:mo>]</m:mo>
+ </m:mrow>
+ </m:math>
+ </inlineequation>. Thus intensity values ranging from 0 to 255
+ will be easily accommodated.</para>
+
+ <para>The second question is more difficult to explain: The
+ <xref linkend="glo_Java"/> standard does define <code>int</code>
+ literals. It does however not define <code>short</code> (or
+ <code>byte</code>) literals.</para>
+
+ <para>Thus the sequence 0B01111111_11111111 will be treated as
+ an integer value which is compatible with a short and is thus
+ assignable.</para>
+
+ <para>On the other hand the <code>int</code> literal
+ <code>0B10000000_00000000</code> evaluates to +32768 and can
+ thus not be assigned to a short at all not to mention its non-
+ <link
+ xlink:href="http://en.wikipedia.org/wiki/Two's_complement#firstHeading">Two's
+ complement</link> representation. In order to avoid this error
+ we need an explicit cast:</para>
+
+ <programlisting language="java">short minumum = (short) 0B10000000_00000000;</programlisting>
+
+ <para>Since a short ranges from -32768 to 32767 we may as well
+ use a unary minus sign instead:</para>
+
+ <programlisting>short minumum = -0B10000000_00000000;</programlisting>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+ </section>
+ </section>
+
+ <section xml:id="sd1SimpleExpressions">
+ <title>Simple expressions</title>
+
+ <qandaset defaultlabel="qanda" xml:id="sw1QandaSquareArea">
+ <title>Calculating the area of a square</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>The area <inlineequation>
+ <m:math display="inline">
+ <m:mi>a</m:mi>
+ </m:math>
+ </inlineequation> of a given square having radius
+ <inlineequation>
+ <m:math display="inline">
+ <m:mi>r</m:mi>
+ </m:math>
+ </inlineequation> is being obtained by <inlineequation>
+ <m:math display="inline">
+ <m:mrow>
+ <m:mi>a</m:mi>
+
+ <m:mo>=</m:mo>
+
+ <m:mrow>
+ <m:mi>Ï€</m:mi>
+
+ <m:mo>×</m:mo>
+
+ <m:msup>
+ <m:mi>r</m:mi>
+
+ <m:mi>2</m:mi>
+ </m:msup>
+ </m:mrow>
+ </m:mrow>
+ </m:math>
+ </inlineequation>. Complete the following code to calculate the
+ result and write it to standard output using
+ <code>System.out.println(...)</code>:</para>
+
+ <programlisting language="java">public static void main(String[] args) {
+
+ double radius = 2.31; // A square having a radius (given e.g. in mm).
+ double pi = 3.1415926; // Constant relating a square's radius, perimeter and area.
+
+ // TODO: Write the circle's area to standard output
+}</programlisting>
+
+ <tip>
+ <para>You may want to read the <link
+ xlink:href="http://proquest.safaribooksonline.com/9780992133047/toc1_html_4">overview
+ section</link> on statements.</para>
+ </tip>
+ </question>
+
+ <answer>
+ <glosslist>
+ <glossentry>
+ <glossterm>Using a mere expression</glossterm>
+
+ <glossdef>
+ <programlisting language="java">public static void main(String[] args) {
+
+ double radius = 2.31; // A square having a radius (given e.g. in mm).
+ double pi = 3.1415926; // Constant relating a square's radius, perimeter and area.
+
+ System.out.println(pi * radius * radius);
+}</programlisting>
+ </glossdef>
+ </glossentry>
+
+ <glossentry>
+ <glossterm>Using a variable</glossterm>
+
+ <glossdef>
+ <para>Instead of immediately using the expression as an
+ argument to <code>System.out.println(...)</code> we may
+ assign its value to a variable prior to output
+ creation:</para>
+
+ <programlisting language="java">public static void main(String[] args) {
+
+ double radius = 2.31; // A square having a radius (given e.g. in mm).
+ double pi = 3.1415926; // Constant relating a square's radius, perimeter and area.
+
+ double area = pi * radius * radius;
+ System.out.println(area);
+}</programlisting>
+ </glossdef>
+ </glossentry>
+ </glosslist>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+
+ <section xml:id="sd1ExpressionStrangeThings">
+ <title>Strange things happen</title>
+
+ <qandaset defaultlabel="qanda" xml:id="sw1QandaByteOverflow">
+ <title>Calculating the area of a square</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>Consider the following code snippet:</para>
+
+ <programlisting language="java">byte a = 127;
+System.out.println("value=" + a);
+a++;
+System.out.println("New value=" + a);
+</programlisting>
+
+ <para>This will produce the following output:</para>
+
+ <programlisting language="none">value=127
+New value=-128</programlisting>
+
+ <para>Explain this strange behaviour. Moreover you'll find the
+ following code to rise a compile time error:</para>
+
+ <programlisting language="java">byte a = 127;
+System.out.println("value=" + a);
+a = a + 1; // Error: Type mismatch: cannot convert from int to byte
+System.out.println("New value=" + a);</programlisting>
+
+ <tip>
+ <para>You may want to read the <link
+ xlink:href="http://proquest.safaribooksonline.com/9780992133047/toc1_html_4">overview
+ section</link> on statements.</para>
+ </tip>
+ </question>
+
+ <answer>
+ <para>A byte variable ranges from -128 to +127. Thus
+ incrementing 127 by 1 yields an overflow error.</para>
+
+ <para>Since <xref linkend="glo_Java"/> uses <link
+ xlink:href="http://en.wikipedia.org/wiki/Two's_complement#firstHeading">Two's
+ complement</link> representation we have:</para>
+
+ <informaltable border="1">
+ <tr>
+ <td><code> 01111111</code></td>
+
+ <td><code> 127</code></td>
+ </tr>
+
+ <tr>
+ <td><code>+00000001</code></td>
+
+ <td><code> +1</code></td>
+ </tr>
+
+ <tr>
+ <td><code>=10000000</code></td>
+
+ <td><code>=-128</code></td>
+ </tr>
+ </informaltable>
+
+ <para>On machine level the above calculation is just an ordinary
+ addition.</para>
+
+ <para>Conclusion: Watch out when doing (integer) arithmetic!
+ </para>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+ </section>
+ </section>
+
+ <section xml:id="sw1StringLiterals">
+ <title>Dealing with strings</title>
+
+ <qandaset defaultlabel="qanda" xml:id="sw1QandaStringVariableMix">
+ <title>Composing strings of literals and variables</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>Consider the following code:</para>
+
+ <programlisting language="java">public static void main(String[] args) {
+ System.out.println("Some 'special' words.");
+}</programlisting>
+
+ <para>The corresponding output will be <computeroutput>Some
+ 'special' words.</computeroutput>. Change the above code to
+ replace the single quotes by double quotes producing the output
+ <computeroutput>Some "special" words.</computeroutput>
+ instead.</para>
+
+ <tip>
+ <para>Hunt for <quote>java escape double quote</quote> and read
+ about <link
+ xlink:href="http://proquest.safaribooksonline.com/book/programming/java/9780992133047/chapter-2-language-fundamentals/toc6_html_2#readertoolbar2">character
+ literals</link>.</para>
+ </tip>
+ </question>
+
+ <answer>
+ <para>There are at least two solutions on offer:</para>
+
+ <glosslist>
+ <glossentry>
+ <glossterm>Perfectly obvious</glossterm>
+
+ <glossdef>
+ <para>Inside a string literal the terminating character (")
+ may be escaped using a backslash (\):</para>
+
+ <programlisting language="java">System.out.println("Some \"special\" words.");</programlisting>
+ </glossdef>
+ </glossentry>
+
+ <glossentry>
+ <glossterm>Even more clumsy</glossterm>
+
+ <glossdef>
+ <para>Double quotes may be represented by the character (not
+ string!) literal <quote>'"'</quote>. We may then compose our
+ output string by:</para>
+
+ <programlisting language="java">System.out.println("Some " + '"' + "special" + '"' + " words.");</programlisting>
+ </glossdef>
+ </glossentry>
+ </glosslist>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+
+ <qandaset defaultlabel="qanda" xml:id="sw1QandaStringEscapeDoubleQuote">
+ <title>Escaping double quotes</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>Consider the following code:</para>
+
+ <programlisting language="java">public static void main(String[] args) {
+ System.out.println("Some 'special' words.");
+}</programlisting>
+
+ <para>The corresponding output will be <computeroutput>Some
+ 'special' words.</computeroutput>. Change the above code to
+ replace the single quotes by double quotes producing the output
+ <computeroutput>Some "special" words.</computeroutput>
+ instead.</para>
+
+ <tip>
+ <para>Hunt for <quote>java escape double quote</quote> and read
+ about <link
+ xlink:href="http://proquest.safaribooksonline.com/book/programming/java/9780992133047/chapter-2-language-fundamentals/toc6_html_2#readertoolbar2">character
+ literals</link>.</para>
+ </tip>
+ </question>
+
+ <answer>
+ <para>There are at least two solutions on offer:</para>
+
+ <glosslist>
+ <glossentry>
+ <glossterm>Perfectly obvious</glossterm>
+
+ <glossdef>
+ <para>Inside a string literal the terminating character (")
+ may be escaped using a backslash (\):</para>
+
+ <programlisting language="java">System.out.println("Some \"special\" words.");</programlisting>
+ </glossdef>
+ </glossentry>
+
+ <glossentry>
+ <glossterm>Even more clumsy</glossterm>
+
+ <glossdef>
+ <para>Double quotes may be represented by the character (not
+ string!) literal <quote>'"'</quote>. We may then compose our
+ output string by:</para>
+
+ <programlisting language="java">System.out.println("Some " + '"' + "special" + '"' + " words.");</programlisting>
+ </glossdef>
+ </glossentry>
+ </glosslist>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+ </section>
+
+ <section xml:id="sw1LanguageFundamentalUsingFinal">
+ <title>Using <code>final</code></title>
+
+ <qandaset defaultlabel="qanda" xml:id="sw1QandaSquareAreaFinal">
+ <title>Calculating the area of a square avoiding accidental
+ redefinition</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>In Exercise <xref linkend="sw1QandaSquareArea"/> you
+ calculated a given square's area:</para>
+
+ <programlisting language="java"> public static void main(String[] args) {
+
+ double radius = 2.31; // A square having a radius (given e.g. in mm).
+ double pi = 3.1415926; // Constant relating a square's radius, perimeter and area.
+
+ double area = pi * radius * radius;
+ System.out.println(area);
+ }</programlisting>
+
+ <para>Though there is nothing wrong with this approach but it may
+ be considered error prone. A careless programmer may accidentally
+ redefine the value of <code>pi</code>:</para>
+
+ <programlisting language="java"> public static void main(String[] args) {
+
+ double radius = 2.31; // A square having a radius (given e.g. in mm).
+ double pi = 3.1415926; // Constant relating a square's radius, perimeter and area.
+
+ // Some lines of code in between
+ // ...
+
+ pi = -17; // Woops! This shall not happen!
+
+ // More lines of code
+ // ...
+
+ double area = pi * radius * radius;
+ System.out.println(area);
+ }</programlisting>
+
+ <para>Modify the original code to avoid this type of error.</para>
+
+ <tip>
+ <para>You may want to read the <quote
+ xlink:href="http://proquest.safaribooksonline.com/9780992133047/toc5_html_2">Constants</quote>
+ section.</para>
+ </tip>
+ </question>
+
+ <answer>
+ <para>The solution is straightforward. We add the
+ <code>final</code> modifier to the definition of our variable
+ <code>pi</code>:</para>
+
+ <programlisting language="java" linenumbering="numbered">public static void main(String[] args) {
+
+ double radius = 2.31; // A square having a radius (given e.g. in mm).
+ <emphasis role="bold">final</emphasis> double pi = 3.1415926; // Creating pi as a constant (non-modifiable/assignable) variable.
+
+ // Longer code section in between
+ // ...
+
+ pi = -17; // Compile time error.
+
+ // Another longer code section
+ // ...
+
+ <emphasis role="bold">final</emphasis> double area = pi * radius * radius;
+ System.out.println(area);
+}</programlisting>
+
+ <para>Now our flawed assignment at line 9 will be flagged as a
+ compile time error:</para>
+
+ <para><computeroutput>The final local variable pi cannot be
+ assigned. It must be blank and not using a compound
+ assignment</computeroutput></para>
+
+ <para>Note the second <code>final</code> modification in the
+ definition of our variable <code>area</code> to avoid erroneous
+ redefinitions as well.</para>
+
+ <para>As a rule of thumb: Whenever you expect a variable not to
+ change after initial assignment use <code>final</code> to declare
+ it as being constant.</para>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+ </section>
+</chapter>
diff --git a/Doc/Sd1/steinbruch.xml b/Doc/Sd1/steinbruch.xml
new file mode 100644
index 000000000..90c9d3e53
--- /dev/null
+++ b/Doc/Sd1/steinbruch.xml
@@ -0,0 +1,134 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<chapter version="5.0" xml:id="steinbruch"
+ xmlns="http://docbook.org/ns/docbook"
+ xmlns:xlink="http://www.w3.org/1999/xlink"
+ xmlns:xi="http://www.w3.org/2001/XInclude"
+ 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 xml:id="sw1Steinbruch" xml:lang="de">Steinbruch</title>
+
+ <qandaset defaultlabel="qanda" xml:id="sw1QandaSquareAreaMathPackage">
+ <title>Using constants from the <classname
+ xlink:href="http://docs.oracle.com/javase/8/docs/api/java/lang/Math.html">java.lang.Math</classname>
+ class.</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>In Exercise <xref linkend="sw1QandaSquareAreaFinal"/> you
+ calculated a given square's area protecting variables against
+ accidental redefinition using the <code>final</code>
+ modifier:</para>
+
+ <programlisting language="java">public static void main(String[] args) {
+
+ double radius = 2.31; // A square having a radius (given e.g. in mm).
+ final double pi = 3.1415926; // Creating pi as a constant (non-modifiable/assignable) variable.
+
+ final double area = pi * radius * radius;
+ System.out.println(area);
+}</programlisting>
+
+ <para>You may have wondered why you had to punch in the value of
+ <inlineequation>
+ <m:math display="inline">
+ <m:mi>Ï€</m:mi>
+ </m:math>
+ </inlineequation> yourself. Actually <xref linkend="glo_Java"/>
+ predefines a lot of constants in its standard <classname
+ xlink:href="http://docs.oracle.com/javase/8/docs/api/java/lang/Math.html">java.lang.Math</classname>
+ class. Read its documentation to replace your own <code>pi</code>
+ variable.</para>
+
+ <tip>
+ <para>You may want to read the <quote
+ xlink:href="http://proquest.safaribooksonline.com/9780992133047/toc11_html_2">Static
+ Members</quote> and <quote
+ xlink:href="http://proquest.safaribooksonline.com/9780992133047/toc6_html_4">Java
+ Packages</quote> sections .</para>
+ </tip>
+ </question>
+
+ <answer>
+ <para>The short answer simply is:</para>
+
+ <programlisting language="java" linenumbering="numbered">public static void main(String[] args) {
+
+ double radius = 2.31; // A square having a radius (given e.g. in mm).
+
+ final double area = Math.PI * radius * radius;
+ System.out.println(area);
+}</programlisting>
+
+ <para>In case you bother about the somewhat clumsy Math.PI rather
+ than just having PI itself some syntactic sugar may be added on
+ top:</para>
+
+ <programlisting language="java" linenumbering="numbered">import static java.lang.Math.PI;
+
+public class CircleAreaCalculator {
+
+ public static void main(String[] args) {
+
+ double radius = 2.31; // A square having a radius (given e.g. in mm).
+
+ final double area = PI * radius * radius;
+ System.out.println(area);
+ }
+}</programlisting>
+
+ <para>We dig a little deeper to fully understand the underlying
+ concepts. Obtaining a <xref linkend="glo_JDK"/>'s source code and
+ browsing its implementation <filename>Math.java</filename>
+ reveals:</para>
+
+ <programlisting language="java">/*
+ * Copyright (c) 1994, 2011, Oracle and/or its affiliates. All rights reserved.
+ * ...
+ */
+
+package java.lang;
+...
+
+public final class Math {
+
+...
+ /**
+ * The {@code double} value that is closer than any other to
+ * <i>pi</i>, the ratio of the circumference of a circle to its
+ * diameter.
+ */
+ <emphasis role="bold">public static final double PI = 3.14159265358979323846;</emphasis>
+...</programlisting>
+
+ <para>This accounts for using the expression <code><varname
+ xlink:href="http://docs.oracle.com/javase/8/docs/api/java/lang/Math.html#field.summary">Math.PI</varname></code>.
+ The careful reader may have expected an <code>import</code>
+ statement in order to use the <classname
+ xlink:href="http://docs.oracle.com/javase/8/docs/api/java/lang/Math.html">Math</classname>
+ class:</para>
+
+ <programlisting language="java">import java.lang.<emphasis
+ role="bold">Math</emphasis>; // Optional: Classes from java.lang are imported
+ // automatically as per Java language specification.
+
+public class CircleAreaCalculator {
+
+ public static void main(String[] args) {
+
+ double radius = 2.31; // A square having a radius (given e.g. in mm).
+
+ final double area = <emphasis role="bold">Math</emphasis>.PI * radius * radius;
+ System.out.println(area);
+ }
+}</programlisting>
+
+ <para>The comment states the mere fact that this import is simply
+ unnecessary.</para>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+</chapter>
diff --git a/Doc/lectures.xml b/Doc/lectures.xml
index 1483f1618..c4c886c98 100644
--- a/Doc/lectures.xml
+++ b/Doc/lectures.xml
@@ -30,14 +30,24 @@
</info>
<xi:include href="Sd1/preliminaries.xml" xpointer="element(/1)"/>
+
+ <xi:include href="Sd1/languageFundamentals.xml" xpointer="element(/1)"/>
+
+ <xi:include href="Sd1/steinbruch.xml" xpointer="element(/1)"/>
+
<xi:include href="Sd1/class.xml" xpointer="element(/1)"/>
+
<xi:include href="Sd1/loop.xml" xpointer="element(/1)"/>
+
<xi:include href="Sd1/array.xml" xpointer="element(/1)"/>
+
<xi:include href="Sd1/identity.xml" xpointer="element(/1)"/>
+
<xi:include href="Sd1/deployment.xml" xpointer="element(/1)"/>
+
<xi:include href="Sd1/streams.xml" xpointer="element(/1)"/>
- <xi:include href="Sd1/collections.xml" xpointer="element(/1)"/>
+ <xi:include href="Sd1/collections.xml" xpointer="element(/1)"/>
</part>
<part xml:id="sda1">
@@ -62,7 +72,6 @@
<xi:include href="Sda1/testng.xml" xpointer="element(/1)"/>
<xi:include href="Sda1/fo.xml" xpointer="element(/1)"/>
-
</part>
<part xml:id="sda2">
@@ -71,11 +80,13 @@
</info>
<xi:include href="Sda2/ldap.xml" xpointer="element(/1)"/>
+
<xi:include href="Sda2/jpa.xml" xpointer="element(/1)"/>
+
<xi:include href="Sda2/jax-rs.xml" xpointer="element(/1)"/>
</part>
<xi:include href="Common/bibliography.xml" xpointer="element(/1)"/>
- <xi:include href="Common/glossary.xml" xpointer="element(/1)"/>
+ <xi:include href="Common/glossary.xml" xpointer="element(/1)"/>
</book>
--
GitLab