From c419f2be7a597c85c18764cdd402d34a21241765 Mon Sep 17 00:00:00 2001
From: Martin Goik <goik@hdm-stuttgart.de>
Date: Mon, 22 Jan 2018 11:22:02 +0100
Subject: [PATCH] Up to random number generation
---
.../sd1/CreateCustomNumberFormat.java | 24 ++
.../sd1/GetAvailableLocales.java | 15 ++
.../sd1/GetNumberFormatInstance.java | 18 ++
.../sd1/PolymorphicNumberParsing.java | 26 ++
.../de/hdm_stuttgart/sd1/RandomExample.java | 26 ++
.../de/hdm_stuttgart/sd1/RoundingProblem.java | 34 +++
Doc/Sd1/workingWithNumbers.xml | 254 ++++++++++++++++--
7 files changed, 377 insertions(+), 20 deletions(-)
create mode 100644 Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/CreateCustomNumberFormat.java
create mode 100644 Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/GetAvailableLocales.java
create mode 100644 Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/GetNumberFormatInstance.java
create mode 100644 Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/PolymorphicNumberParsing.java
create mode 100644 Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/RandomExample.java
create mode 100644 Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/RoundingProblem.java
diff --git a/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/CreateCustomNumberFormat.java b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/CreateCustomNumberFormat.java
new file mode 100644
index 000000000..4ed8f9c41
--- /dev/null
+++ b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/CreateCustomNumberFormat.java
@@ -0,0 +1,24 @@
+package de.hdm_stuttgart.sd1;
+
+import java.text.DecimalFormat;
+import java.text.DecimalFormatSymbols;
+import java.text.NumberFormat;
+import java.util.Locale;
+
+public class CreateCustomNumberFormat {
+
+ public static void main(String[] args) {
+
+ final DecimalFormatSymbols unusualSymbols = new DecimalFormatSymbols(Locale.getDefault());
+ unusualSymbols.setDecimalSeparator('|');
+ unusualSymbols.setGroupingSeparator('^');
+
+ final String strange = "#,##0.###";
+ final DecimalFormat weirdFormatter = new DecimalFormat(strange, unusualSymbols);
+ weirdFormatter.setGroupingSize(4);
+
+ String bizarre = weirdFormatter.format(12345.678);
+ System.out.println(bizarre);
+
+ }
+}
diff --git a/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/GetAvailableLocales.java b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/GetAvailableLocales.java
new file mode 100644
index 000000000..246f4be9d
--- /dev/null
+++ b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/GetAvailableLocales.java
@@ -0,0 +1,15 @@
+package de.hdm_stuttgart.sd1;
+
+import java.util.Locale;
+import java.util.Scanner;
+
+public class GetAvailableLocales {
+
+ public static void main(String[] args) {
+
+ System.out.println(Locale.getAvailableLocales().length + " locales available:");
+ for (final Locale l: Locale.getAvailableLocales()) {
+ System.out.println("Locale: " + l.getDisplayLanguage() + "(" + l + ")");
+ }
+ }
+}
diff --git a/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/GetNumberFormatInstance.java b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/GetNumberFormatInstance.java
new file mode 100644
index 000000000..8c6d82801
--- /dev/null
+++ b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/GetNumberFormatInstance.java
@@ -0,0 +1,18 @@
+package de.hdm_stuttgart.sd1;
+
+import java.text.DecimalFormat;
+import java.text.NumberFormat;
+import java.util.Locale;
+
+public class GetNumberFormatInstance {
+
+ public static void main(String[] args) {
+
+ final NumberFormat standard = new DecimalFormat(); // Default locale
+ System.out.println(standard.format(1234.5678));
+
+ final NumberFormat de = DecimalFormat.getInstance(Locale.GERMANY);
+ System.out.println(de.format(1234.5678));
+
+ }
+}
diff --git a/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/PolymorphicNumberParsing.java b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/PolymorphicNumberParsing.java
new file mode 100644
index 000000000..6f357105a
--- /dev/null
+++ b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/PolymorphicNumberParsing.java
@@ -0,0 +1,26 @@
+package de.hdm_stuttgart.sd1;
+
+import java.text.DecimalFormat;
+import java.text.DecimalFormatSymbols;
+import java.text.NumberFormat;
+import java.text.ParseException;
+import java.util.Locale;
+
+public class PolymorphicNumberParsing {
+
+ public static void main(String[] args) {
+
+ final NumberFormat de = NumberFormat.getInstance(Locale.GERMANY);
+ try {
+ final Number[] values = {
+ de.parse("103.234"),
+ de.parse("400.000,234")};
+
+ for (final Number n: values) {
+ System.out.println(n + "(" + n.getClass().getTypeName() + ")");
+ }
+ } catch (ParseException e) {
+ e.printStackTrace();
+ }
+ }
+}
diff --git a/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/RandomExample.java b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/RandomExample.java
new file mode 100644
index 000000000..d930a381f
--- /dev/null
+++ b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/RandomExample.java
@@ -0,0 +1,26 @@
+package de.hdm_stuttgart.sd1;
+
+import java.util.Random;
+import java.util.Scanner;
+
+public class RandomExample {
+
+ public static void main(String[] args) {
+
+
+ try(final Scanner scanner = new Scanner(System.in)) {
+ System.out.print("Enter an integer seed:");
+ final long seed = scanner.nextLong();
+
+ Random generator = new Random(seed);
+ for (int i = 0; i < 10; i++) {
+ System.out.print(generator.nextBoolean() + " ");
+ }
+ }
+
+ }
+
+
+
+
+}
diff --git a/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/RoundingProblem.java b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/RoundingProblem.java
new file mode 100644
index 000000000..49798c10a
--- /dev/null
+++ b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/RoundingProblem.java
@@ -0,0 +1,34 @@
+package de.hdm_stuttgart.sd1;
+
+import java.math.BigDecimal;
+
+public class RoundingProblem {
+
+ public static void main(String[] args) {
+ f();
+ d();
+ bd();
+ }
+
+ static void f() {
+ final float result = 0.99f - 0.1f -0.1f -0.1f;
+ System.out.println(result);
+ }
+ static void d() {
+ final double result = 0.99 - 0.1 -0.1 -0.1;
+ System.out.println(result);
+ }
+
+ static void bd() {
+ final BigDecimal zero_dot_99 = new BigDecimal("0.99");
+ final BigDecimal zero_dot_1 = new BigDecimal("0.1");
+
+ BigDecimal result = zero_dot_99.
+ subtract(zero_dot_1).
+ subtract(zero_dot_1).
+ subtract(zero_dot_1);
+
+ System.out.println(result);
+ }
+
+}
diff --git a/Doc/Sd1/workingWithNumbers.xml b/Doc/Sd1/workingWithNumbers.xml
index 630dc0ff2..e16e22e82 100644
--- a/Doc/Sd1/workingWithNumbers.xml
+++ b/Doc/Sd1/workingWithNumbers.xml
@@ -21,12 +21,12 @@
of integer values</title>
<informaltable border="0">
- <colgroup width="83%"/>
+ <colgroup width="87%"/>
- <colgroup width="17%"/>
+ <colgroup width="13%"/>
<tr>
- <td valign="top"><programlisting language="java">final Stack<Integer> values = new Stack<>();
+ <td valign="top"><programlisting language="java">final Stack<Integer> values = new Stack<>();
values.push(3);
values.push(1);
@@ -91,7 +91,7 @@ values.push(1);
values.push(10);
while (!values.empty()) {
- System.out.println(values.pop().
+ System.out.println(values.pop().
getClass().getTypeName());
}</programlisting></td>
@@ -205,9 +205,7 @@ int iPrimitiveFromInteger = <co linkends="sd1_numbers_fig_conventional-3"
</informaltable>
<figure xml:id="sd1_numbers_fig_stackBoxUnboxVsConventional">
- <title><classname
- xlink:href="https://docs.oracle.com/javase/9/docs/api/java/util/Stack.html">Stack</classname>
- usage comparison</title>
+ <title>Boxing syntax comparison</title>
<informaltable border="0">
<colgroup width="50%"/>
@@ -223,7 +221,8 @@ values.push(Integer.valueOf(1));
values.push(Integer.valueOf(10));
while (!values.empty()) {
- System.out.println(values.pop().intValue());
+ System.out.println(values.pop().
+ intValue());
}</programlisting></td>
<td valign="top"><programlisting language="java">final Stack<Integer> values =
@@ -234,7 +233,7 @@ values.push(1);
values.push(10);
while (!values.empty()) {
- System.out.println(values.pop());
+ System.out.println(values.pop());
}</programlisting></td>
</tr>
</informaltable>
@@ -245,7 +244,7 @@ while (!values.empty()) {
<title>Number Parsing</title>
<figure xml:id="sd1_numbers_fig_parseIntegerString">
- <title> Parsing <classname
+ <title>Parsing <classname
xlink:href="https://docs.oracle.com/javase/9/docs/api/java/lang/Integer.html">Integer</classname>
user input</title>
@@ -344,10 +343,12 @@ not an integer.</screen></td>
<colgroup width="50%"/>
<tr>
- <td valign="top"><programlisting language="java">final int value = Integer.parseInt("1101", 2);
-System.out.println("Value: " + value);</programlisting><screen>Value: 13</screen></td>
+ <td valign="top"><programlisting language="java">final int value =
+ Integer.parseInt("1101", 2);
+System.out.println("Value: " + value); </programlisting><screen>Value: 13</screen></td>
- <td valign="top"><programlisting language="java">final int value = Integer.parseInt("201", 2);
+ <td valign="top"><programlisting language="java">final int value =
+ Integer.parseInt("201", 2);
System.out.println("Value: " + value)</programlisting><screen>Exception in thread "main"
java.lang.NumberFormatException:
For input string: "201"
@@ -580,7 +581,118 @@ Exception in thread "main" java.lang.NumberFormatException:
<section xml:id="sd1_numbers_sect_NumberFormatting">
<title>Number Formatting</title>
- <para/>
+ <figure xml:id="sd1_numbers_fig_locale">
+ <title>Excerpt from <classname
+ xlink:href="https://docs.oracle.com/javase/9/docs/api/java/util/Locale.html">java.util.Locale</classname></title>
+
+ <para>A Locale object represents a specific geographical, political, or
+ cultural region.</para>
+
+ <para>An operation that requires a Locale to perform its task is called
+ locale-sensitive and uses the Locale to tailor information for the
+ user.</para>
+
+ <para>For example, displaying a number is a locale-sensitive operation—
+ the number should be formatted according to the customs and conventions
+ of the user's native country, region, or culture.</para>
+ </figure>
+
+ <figure xml:id="sd1_numbers_fig_localeProperties">
+ <title><classname
+ xlink:href="https://docs.oracle.com/javase/9/docs/api/java/util/Locale.html">Locale</classname>
+ properties</title>
+
+ <itemizedlist>
+ <listitem>
+ <para>Language</para>
+ </listitem>
+
+ <listitem>
+ <para>Encoding</para>
+ </listitem>
+
+ <listitem>
+ <para>Country</para>
+ </listitem>
+
+ <listitem>
+ <para>Extensible</para>
+ </listitem>
+ </itemizedlist>
+ </figure>
+
+ <figure xml:id="sd1_numbers_fig_constructNumberFormat">
+ <title>Get a <classname
+ xlink:href="https://docs.oracle.com/javase/9/docs/api/java/text/NumberFormat.html">NumberFormat</classname>
+ instance</title>
+
+ <programlisting language="java">final NumberFormat standard = new DecimalFormat();
+System.out.println(standard.format(1234.5678));
+
+final NumberFormat de = DecimalFormat.getInstance(Locale.GERMANY);
+System.out.println(de.format(1234.5678));</programlisting>
+
+ <screen>1,234.568
+1.234,568</screen>
+ </figure>
+
+ <figure xml:id="sd1_numbers_fig_customFormat">
+ <title>Create a custom formatter</title>
+
+ <programlisting language="java">final DecimalFormatSymbols unusualSymbols =
+ new DecimalFormatSymbols(Locale.getDefault());
+unusualSymbols.setDecimalSeparator('|');
+unusualSymbols.setGroupingSeparator('^');
+
+final String strange = "#,##0.###";
+final DecimalFormat weirdFormatter = new DecimalFormat(strange, unusualSymbols);
+weirdFormatter.setGroupingSize(4);
+
+System.out.println(weirdFormatter.format(12345.678));</programlisting>
+
+ <screen>1^2345|678</screen>
+ </figure>
+
+ <qandaset defaultlabel="qanda"
+ xml:id="sd1_numbers_qanda_getAvailableLocales">
+ <title><classname
+ xlink:href="https://docs.oracle.com/javase/9/docs/api/java/util/Locale.html">Locale</classname>
+ definitions</title>
+
+ <qandadiv>
+ <qandaentry>
+ <question>
+ <para>Each <xref linkend="glo_JRE"/> ships with a set of available
+ <classname
+ xlink:href="https://docs.oracle.com/javase/9/docs/api/java/util/Locale.html">Locale</classname>
+ definitions. Write a simple program to get the following
+ list:</para>
+
+ <screen>160 locales available:
+Locale: Arabic(ar_AE)
+Locale: Arabic(ar_JO)
+Locale: Arabic(ar_SY)
+Locale: Croatian(hr_HR)
+...
+Locale: Indonesian(in_ID)
+Locale: English(en_GB)</screen>
+
+ <tip>
+ <para>Read the documentation of <classname
+ xlink:href="https://docs.oracle.com/javase/9/docs/api/java/util/Locale.html">Locale</classname>
+ to find appropriate methods.</para>
+ </tip>
+ </question>
+
+ <answer>
+ <programlisting language="java">System.out.println(Locale.getAvailableLocales().length + " locales available:");
+for (final Locale l: Locale.getAvailableLocales()) {
+ System.out.println("Locale: " + l.getDisplayLanguage() + "(" + l + ")");
+}</programlisting>
+ </answer>
+ </qandaentry>
+ </qandadiv>
+ </qandaset>
<qandaset defaultlabel="qanda"
xml:id="sd1_numbers_qanda_formatIntDoubleDate">
@@ -733,23 +845,125 @@ static public void print(final LocalDate date, final Locale locale) {
</qandaentry>
</qandadiv>
</qandaset>
- </section>
- <section xml:id="sd1_numbers_sect_java.lang.Math">
- <title>The java.lang.Math Class</title>
+ <figure xml:id="sd1_numbers_fig_polymorphicNumberParsing">
+ <title>Polymorphic number parsing</title>
+
+ <programlisting language="java">final NumberFormat de = NumberFormat.getInstance(Locale.GERMANY);
+try {
+ final Number[] values = {
+ de.parse("103.234"),
+ de.parse("400.000,234")};
+
+ for (final Number n: values) {
+ System.out.println(n + "(" + n.getClass().getTypeName() + ")");
+ }
+} catch (ParseException e) {
+ e.printStackTrace();
+}</programlisting>
- <para/>
+ <screen>103234(java.lang.Long)
+400000.234(java.lang.Double)</screen>
+ </figure>
</section>
<section xml:id="sd1_numbers_sect_WorkingwithMoney">
<title>Working with Money</title>
- <para/>
+ <figure xml:id="sd1_numbers_fig_floatLimitedPreceision">
+ <title>Limited <code language="java">float</code> precision</title>
+
+ <programlisting language="java">final float result = 0.99f - 0.1f -0.1f -0.1f;
+System.out.println(result);</programlisting>
+
+ <screen>0.68999994</screen>
+ </figure>
+
+ <figure xml:id="sd1_numbers_fig_doubleLimitedPreceision">
+ <title>Limited <code language="java">double</code> precision</title>
+
+ <programlisting language="java">final double result = 0.99 - 0.1 -0.1 -0.1;
+System.out.println(result);</programlisting>
+
+ <screen>0.6900000000000001</screen>
+ </figure>
+
+ <figure xml:id="sd1_numbers_fig_usingBigDecimal">
+ <title>Using <classname
+ xlink:href="https://docs.oracle.com/javase/9/docs/api/java/math/BigDecimal.html">BigDecimal</classname></title>
+
+ <programlisting language="java">final BigDecimal zero_dot_99 = new BigDecimal("0.99");
+final BigDecimal zero_dot_1 = new BigDecimal("0.1");
+
+BigDecimal result = zero_dot_99.
+ subtract(zero_dot_1).
+ subtract(zero_dot_1).
+ subtract(zero_dot_1);
+
+System.out.println(result);</programlisting>
+
+ <screen>0.69</screen>
+ </figure>
+
+ <figure xml:id="sd1_numbers_fig_usingBigDecimalFeatures">
+ <title><classname
+ xlink:href="https://docs.oracle.com/javase/9/docs/api/java/math/BigDecimal.html">BigDecimal</classname>
+ features</title>
+
+ <itemizedlist>
+ <listitem>
+ <para>Higher memory allocation hosting higher precision.</para>
+ </listitem>
+
+ <listitem>
+ <para>Immutable instances</para>
+ </listitem>
+
+ <listitem>
+ <para>Calculation performance penalty.</para>
+ </listitem>
+
+ <listitem>
+ <para>Clumsy interface.</para>
+ </listitem>
+ </itemizedlist>
+ </figure>
</section>
<section xml:id="sd1_numbers_sect_GeneratingRandomNumbers">
<title>Generating Random Numbers</title>
- <para/>
+ <figure xml:id="sd1_numbers_fig_random">
+ <title>Using <methodname
+ xlink:href="https://docs.oracle.com/javase/9/docs/api/java/lang/Math.html#random--">static
+ double random​()</methodname></title>
+
+ <programlisting language="java">for (int i = 0; i < 10; i++) {
+ System.out.println(Math.random());
+}</programlisting>
+
+ <screen>0.4754286988826202
+0.0060114391743414375
+...
+0.9047785351372987
+0.2516070321935864</screen>
+ </figure>
+
+ <figure xml:id="sd1_numbers_fig_randomSeed">
+ <title>Seeding a pseudo random generator</title>
+
+ <programlisting language="java">try(final Scanner scanner = new Scanner(System.in)) {
+ System.out.print("Enter an integer seed:");
+ final long seed = scanner.nextLong();
+
+ Random generator = new Random(seed);
+ for (int i = 0; i < 10; i++) {
+ System.out.print(generator.nextBoolean() + " ");
+ }
+}</programlisting>
+
+ <screen>Enter an integer seed:4237549835735
+false true true true false false false true false true </screen>
+ </figure>
</section>
</chapter>
--
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