From 62a70d9881d9d27a944b5e6a2aaaa0b3ba055cfd Mon Sep 17 00:00:00 2001
From: Martin Goik <goik@hdm-stuttgart.de>
Date: Mon, 14 Sep 2015 20:46:04 +0200
Subject: [PATCH] time conversion exercise
---
Doc/Sd1/languageFundamentals.xml | 235 ++++++++++++++++++++++---------
1 file changed, 170 insertions(+), 65 deletions(-)
diff --git a/Doc/Sd1/languageFundamentals.xml b/Doc/Sd1/languageFundamentals.xml
index 7e9028c6c..a122198a5 100644
--- a/Doc/Sd1/languageFundamentals.xml
+++ b/Doc/Sd1/languageFundamentals.xml
@@ -583,8 +583,8 @@ System.out.println("Maximum short value:" + maximum);
</question>
<answer>
- <para>Since <code>short</code> variables are being represented
- by to bytes their range is <inlineequation>
+ <para>Since variables of type <code>short</code> are being
+ represented by to bytes their range is <inlineequation>
<m:math display="inline">
<m:mrow>
<m:mo>[</m:mo>
@@ -632,7 +632,7 @@ System.out.println("Maximum short value:" + maximum);
<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-
+ 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
@@ -651,49 +651,50 @@ System.out.println("Maximum short value:" + maximum);
</section>
</section>
- <section xml:id="sd1SimpleExpressions">
+ <section xml:id="sw1SectSquareArea">
<title>Simple expressions</title>
- <qandaset defaultlabel="qanda" xml:id="sw1QandaSquareArea">
- <title>Calculating square's area</title>
+ <section xml:id="sd1SquareArea">
+ <title>Calculating a square's area</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>
+ <qandaset defaultlabel="qanda" xml:id="sw1QandaSquareArea">
+ <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:mo>=</m:mo>
- <m:mrow>
- <m:mi>Ï€</m:mi>
+ <m:mrow>
+ <m:mi>Ï€</m:mi>
- <m:mo>×</m:mo>
+ <m:mo>×</m:mo>
- <m:msup>
- <m:mi>r</m:mi>
+ <m:msup>
+ <m:mi>r</m:mi>
- <m:mi>2</m:mi>
- </m:msup>
+ <m:mi>2</m:mi>
+ </m:msup>
+ </m:mrow>
</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>
+ </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="noneJava">public static void main(String[] args) {
+ <programlisting language="noneJava">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.
@@ -701,39 +702,39 @@ System.out.println("Maximum short value:" + maximum);
// 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>
+ <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>
+ <answer>
+ <glosslist>
+ <glossentry>
+ <glossterm>Using a mere expression</glossterm>
- <glossdef>
- <programlisting language="noneJava">public static void main(String[] args) {
+ <glossdef>
+ <programlisting language="noneJava">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>
+ </glossdef>
+ </glossentry>
- <glossentry>
- <glossterm>Using a variable</glossterm>
+ <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>
+ <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="noneJava">public static void main(String[] args) {
+ <programlisting language="noneJava">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.
@@ -741,13 +742,117 @@ System.out.println("Maximum short value:" + maximum);
double area = pi * radius * radius;
System.out.println(area);
}</programlisting>
- </glossdef>
- </glossentry>
- </glosslist>
- </answer>
- </qandaentry>
- </qandadiv>
- </qandaset>
+ </glossdef>
+ </glossentry>
+ </glosslist>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+ </section>
+
+ <section xml:id="sd1SectTimeUnits">
+ <title>Time unit conversion</title>
+
+ <qandaset defaultlabel="qanda" xml:id="sd1QandaTimeUnits">
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>This exercise consists of two parts:</para>
+
+ <orderedlist>
+ <listitem>
+ <para>Write an application converting a (seconds, minutes
+ ,hours) time specification to seconds:</para>
+
+ <programlisting language="noneJava"> public static void main(String[] args) {
+
+ final int
+ seconds = 31,
+ minutes = 16,
+ hours = 4;
+
+ int timeInSeconds ...
+
+ System.out.println("Time in seconds:" + timeInSeconds);
+ }</programlisting>
+
+ <para>The expected output reads:</para>
+
+ <programlisting language="noneJava">Time in seconds:15391</programlisting>
+ </listitem>
+
+ <listitem>
+ <para>Reverse the previous part of this exercise: Convert a
+ time specification in seconds to (seconds, minutes ,hours)
+ as in:</para>
+
+ <programlisting language="noneJava"> public static void main(String[] args) {
+
+ final int timeInSeconds = 15391;
+
+ ...
+
+ System.out.println("Hours:" + hours);
+ System.out.println("Minutes:" + minutes);
+ System.out.println("Seconds:" + seconds);
+ }</programlisting>
+
+ <para>The expected output reads:</para>
+
+ <programlisting language="noneJava">Hours:4
+Minutes:16
+Seconds:31</programlisting>
+
+ <tip>
+ <para>Consider the <link
+ xlink:href="https://docs.oracle.com/javase/tutorial/java/nutsandbolts/op1.html">remainder
+ operator <quote>%</quote></link> (modulo operator).</para>
+ </tip>
+ </listitem>
+ </orderedlist>
+ </question>
+
+ <answer>
+ <orderedlist>
+ <listitem>
+ <para>A straightforward solution reads:</para>
+
+ <para><programlisting language="noneJava"> public static void main(String[] args) {
+
+ final int
+ seconds = 31,
+ minutes = 16,
+ hours = 4;
+
+ final int timeInSeconds = seconds + 60 * (minutes + 60 * hours);
+
+ System.out.println("Time in seconds:" + timeInSeconds);
+ }</programlisting></para>
+ </listitem>
+
+ <listitem>
+ <programlisting language="noneJava"> public static void main(String[] args) {
+
+ final int timeInSeconds = 15391;
+
+ final int minutesRemaining = timeInSeconds / 60;
+ final int seconds = timeInSeconds % 60;
+
+ final int hours = minutesRemaining / 60;
+ final int minutes = minutesRemaining % 60;
+
+ System.out.println("Hours:" + hours);
+ System.out.println("Minutes:" + minutes);
+ System.out.println("Seconds:" + seconds);
+ }</programlisting>
+ </listitem>
+ </orderedlist>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
+ </section>
<section xml:id="sd1SectInterestSimple">
<title>Interest calculation</title>
@@ -942,7 +1047,7 @@ System.out.println("New value=" + a);</programlisting>
<para>If the expression <code>a + b</code> was of data type
<code>byte</code> an arithmetic overflow as in the subsequent
- code example would occur: </para>
+ code example would occur:</para>
<programlisting language="none"> byte a = 120, b = 10;
--
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