From 2def11c0e770aad15cede66b3937da471e1db943 Mon Sep 17 00:00:00 2001
From: Martin Goik <goik@hdm-stuttgart.de>
Date: Wed, 9 Apr 2014 06:32:58 +0200
Subject: [PATCH] Implementing Rectangles
---
Sd1/swd1.xml | 270 +++++++++++++++---
.../step1/{Driver.java => DriverCircle.java} | 2 +-
.../Sde1/Figur/src/step1/DriverRctangle.java | 19 ++
.../Sde1/Figur/src/step1/Rectangle.java | 61 ++++
.../Sde1/Figur/src/step1/dummy/Rectangle.java | 57 ++++
.../Figur/src/{step2 => step3}/Vector.java | 2 +-
6 files changed, 371 insertions(+), 40 deletions(-)
rename ws/eclipse/Sde1/Figur/src/step1/{Driver.java => DriverCircle.java} (94%)
create mode 100644 ws/eclipse/Sde1/Figur/src/step1/DriverRctangle.java
create mode 100644 ws/eclipse/Sde1/Figur/src/step1/Rectangle.java
create mode 100644 ws/eclipse/Sde1/Figur/src/step1/dummy/Rectangle.java
rename ws/eclipse/Sde1/Figur/src/{step2 => step3}/Vector.java (89%)
diff --git a/Sd1/swd1.xml b/Sd1/swd1.xml
index 267fb23a1..214b4d2ca 100644
--- a/Sd1/swd1.xml
+++ b/Sd1/swd1.xml
@@ -431,7 +431,7 @@
<classname>WombatWorld</classname> constructor's code achieves
the desired behaviour:</para>
- <programlisting>public class WombatWorld {
+ <programlisting language="java">public class WombatWorld {
public WombatWorld() { <emphasis role="bold">// Constructor will be called each time a WombatWorld</emphasis>
super(8, 8, 60); <emphasis role="bold">// is being created</emphasis>
setBackground("cell.jpg");
@@ -627,7 +627,7 @@
definition to consistently replace the following four
definitions:</para>
- <programlisting>public class Wombat extends Actor {
+ <programlisting language="java">public class Wombat extends Actor {
...
<emphasis role="bold">private static final int EAST = 0;
private static final int WEST = 1;
@@ -646,7 +646,7 @@
<para>First we define an appropriate enumeration within our
<classname>Wombat</classname> class:</para>
- <programlisting>public class Wombat extends Actor {
+ <programlisting language="java">public class Wombat extends Actor {
<emphasis role="bold">enum Direction {
EAST, WEST, NORTH, SOUTH
@@ -658,7 +658,7 @@
We may use this newly defined type to redefine our
<code>direction</code> attribute:</para>
- <programlisting>public class Wombat extends Actor {
+ <programlisting language="java">public class Wombat extends Actor {
...
<emphasis role="bold">private Direction direction;</emphasis> // used to be "private int direction"
...</programlisting>
@@ -666,7 +666,7 @@
<para>Our constructor <classname>Wombat()</classname> no
reads:</para>
- <programlisting> public Wombat() {
+ <programlisting language="java"> public Wombat() {
<emphasis role="bold">setDirection(Direction.EAST)</emphasis>; // improved readability, cf. setDirection(0)
leavesEaten = 0;
}</programlisting>
@@ -674,7 +674,7 @@
<para>The <code>setDirection</code> method may be re-written
as:</para>
- <programlisting> public void setDirection(Direction direction) {
+ <programlisting language="java"> public void setDirection(Direction direction) {
this.direction = direction;
switch (direction) {
@@ -696,7 +696,7 @@
<para>This way we got rid of the if clause being present in the
original code:</para>
- <programlisting>public void setDirection(int direction)
+ <programlisting language="java">public void setDirection(int direction)
{
<emphasis role="bold">if ((direction >= 0) && (direction <= 3)) {
this.direction = direction;
@@ -709,7 +709,7 @@
{0,1,2,3}. Re-writing the remaining methods is
straightforward:</para>
- <programlisting> /**
+ <programlisting language="java"> /**
* Move one cell forward in the current direction.
*/
public void move() {
@@ -835,7 +835,7 @@
<answer>
<para>Our <classname>Actor</classname> class contains:</para>
- <programlisting>public class Animal extends Actor
+ <programlisting language="java">public class Animal extends Actor
{
private <co linkends="sd1DefWalkingSpeed-1" xml:id="sde1CoPrivate"/> static <co
linkends="sd1DefWalkingSpeed-2" xml:id="sde1CoStatic"/> final <co
@@ -883,7 +883,7 @@
move with equal speed. Modify the <classname>Animal</classname>
class by adding the following method:</para>
- <programlisting>public void setMyWalkingSpeed(int speed) {...}</programlisting>
+ <programlisting language="java">public void setMyWalkingSpeed(int speed) {...}</programlisting>
<para>This requires the introduction of a new variable within
our <classname>Animal</classname> class. This variable shall be
@@ -902,7 +902,7 @@
role="bold">myWalkingSpeed</emphasis> to account for individual
walking speed values:</para>
- <programlisting>public class Animal extends Actor
+ <programlisting language="java">public class Animal extends Actor
{
private static final double WALKING_SPEED = 5.0; <co
linkends="sd1QandaWalkingSpeed-1"
@@ -1033,7 +1033,7 @@
a new attribute <code>nextTurningAngle</code> of type
<code>int</code>:</para>
- <programlisting>public class Crab extends Animal {
+ <programlisting language="java">public class Crab extends Animal {
<emphasis role="bold">int nexturningAngle = 5;</emphasis> // Initial value
@@ -1060,7 +1060,7 @@
each crab's current state and initialize its value to the first
of our three states:</para>
- <programlisting>public class Crab extends Animal {
+ <programlisting language="java">public class Crab extends Animal {
int nextTurningAngle = 5; <co xml:id="sd1VarCrabState"/> // Crabs start in state 1
@@ -1110,7 +1110,7 @@
maintainability by introducing three integer constants
corresponding to our crabs distinct states:</para>
- <programlisting>public class Crab extends Animal {
+ <programlisting language="java">public class Crab extends Animal {
// These definitions are not strictly required but do help
// understanding the code
@@ -1144,7 +1144,7 @@
<para>Our complete implementation now reads:</para>
- <programlisting>public class Crab extends Animal {
+ <programlisting language="java">public class Crab extends Animal {
// A crab is in exactly one of these states:
final static int state1 = 5,
@@ -1177,16 +1177,12 @@
</chapter>
<chapter xml:id="sd1CrabsEnhance">
- <title>Lecture 5 - Enhancing crabs' behaviour I</title>
+ <title>Lecture 5 - Classes, instances and internal state</title>
<section xml:id="sd1CrabsEnhancePrepare">
<title>Preparations</title>
<itemizedlist>
- <listitem>
- <para>Read chapter 3 of <xref linkend="bibKoelling2010Ger"/>.</para>
- </listitem>
-
<listitem>
<para>Read Chapter 5 from <xref linkend="bibHorton2011"/> excluding
the sections <quote>Recursion</quote> and <quote>Nested
@@ -1212,16 +1208,211 @@
<section xml:id="sd1GeometryClasses">
<title>Dealing with geometry classes</title>
+ <qandaset>
+ <title>Rectangles</title>
+
+ <qandaentry>
+ <question xml:id="sd1ImplementRectangle">
+ <para>Complete the the following class
+ <classname>Rectangle</classname>'s dummy implementation:</para>
+
+ <programlisting language="java">/**
+ * Representing rectangular shapes.
+ *
+ */
+public class Rectangle {
+
+ /**
+ *
+ * @param width The rectangle's width
+ * @param heigth The rectangle's height
+ */
+ public Rectangle (double width, double heigth) {
+ //TODO
+ }
+ /**
+ * @return The rectangle's area.
+ */
+ public double getArea() {
+ return 0; // TODO
+ }
+
+ /**
+ * @return The rectangle's perimeter.
+ */
+ public double getPerimeter() {
+ return 0; // TODO
+ }
+
+ /**
+ * @return The rectangle's width.
+ */
+ public double getWidth() {
+ return 0; // TODO
+ }
+ /**
+ * @param width The rectangle's new width
+ */
+ public void setWidth(double width) {
+ // TODO
+ }
+
+ /**
+ * @return The rectangle's height.
+ */
+ public double getHeight() {
+ return 0; // TODO
+ }
+
+ /**
+ * @param width The rectangle's new height
+ */
+ public void setHeight(double height) {
+ // TODO
+ }
+}</programlisting>
+ </question>
+
+ <answer>
+ <para>First we define two instance (= non-static) variables
+ representing a <classname>Rectangle</classname>'s two parameters
+ <code>width</code> and <code>height</code>:</para>
+
+ <programlisting language="java">public class Rectangle {
+
+ // Instance variables representing a rectangle's parameters
+ private double width, height;
+...
+}</programlisting>
+
+ <para>Next we might allow to change these two parameters:</para>
+
+ <programlisting language="java">public class Rectangle {
+
+ // Instance variables representing a rectangle's parameters
+ private double width, height;
+
+...
+ public void setWidth(double w) {
+ <emphasis role="bold">width = w;</emphasis>
+ }
+
+ /**
+ * @return The rectangle's height.
+ */
+ public void setHeight(double height) {
+ <emphasis role="bold">this.height = height;</emphasis>
+ }
+...
+}</programlisting>
+
+ <para>Notice the subtle difference in the implementation of
+ setWidth(...) and setHeight(...):</para>
+
+ <glosslist>
+ <glossentry>
+ <glossterm><methodname>setWidth(double
+ w)</methodname></glossterm>
+
+ <glossdef>
+ <para>We use the formal parameter name <quote>w</quote>. Its
+ name does not conflict with the instance variable name
+ <quote>width</quote> being defined at class level. We can
+ simply assign this value to our corresponding instance
+ variable using <code>width = w;</code>.</para>
+ </glossdef>
+ </glossentry>
+
+ <glossentry>
+ <glossterm><methodname>setHeight(double
+ height)</methodname></glossterm>
+
+ <glossdef>
+ <para>The method's formal parameter <quote>height</quote>
+ shadows the instance variable's name being defined at class
+ level. We need the <quote>this</quote> keyword in
+ <code>this.height = height;</code> to resolve the
+ ambiguity.</para>
+ </glossdef>
+ </glossentry>
+ </glosslist>
+
+ <para>Both ways are perfectly legal. We continue our
+ implementation:</para>
+
+ <programlisting>/**
+ * Representing rectangular shapes.
+ *
+ */
+public class Rectangle {
+
+ // Instance variables representing a rectangle's parameters
+ private double width, height;
+
+ /**
+ *
+ * @param width The rectangle's width
+ * @param heigth The rectangle's height
+ */
+ public Rectangle (double width, double height) {
+ setWidth(width);
+ setHeight(height);
+ }
+ /**
+ * @return The rectangle's area.
+ */
+ public double getArea() {
+ return width * height;
+ }
+
+ /**
+ * @return The rectangle's perimeter.
+ */
+ public double getPerimeter() {
+ return 2 * (width + height);
+ }
+
+ /**
+ * @return The rectangle's width.
+ */
+ public double getWidth() {
+ return width;
+ }
+ /**
+ * @param width The rectangle's new width
+ */
+ public void setWidth(double w) {
+ width = w;
+ }
+
+ /**
+ * @return The rectangle's height.
+ */
+ public double getHeight() {
+ return height;
+ }
+
+ /**
+ * @param width The rectangle's new height
+ */
+ public void setHeight(double height) {
+ this.height = height;
+ }
+}</programlisting>
+ </answer>
+ </qandaentry>
+ </qandaset>
+
<qandaset defaultlabel="qanda" xml:id="qandasetGeometry">
<title>Circles</title>
<qandadiv>
<qandaentry>
<question>
- <para>Complete the dummy implementation of the following class
- <classname>Circle</classname>:</para>
+ <para>Complete the the following class
+ <classname>Circle</classname>'s dummy implementation:</para>
- <programlisting>package step1.dummy;
+ <programlisting language="java">package step1.dummy;
/**
* A circle of given radius
@@ -1272,7 +1463,7 @@ public class Circle {
<para>Instances of this class shall be usable in the following
fashion:</para>
- <programlisting>public class Driver {
+ <programlisting language="java">public class Driver {
public static void main(String[] args) {
Circle c = new Circle(2.3);
@@ -1295,11 +1486,10 @@ public class Circle {
</question>
<answer>
- <para>We define an instance (= non-static) variable radius
- inside our class <classname>Circle</classname>:</para>
+ <para>We define an instance variable radius inside our class
+ <classname>Circle</classname>:</para>
- <programlisting>package step1;
-...
+ <programlisting language="java">
public class Circle {
double radius;
@@ -1309,7 +1499,7 @@ public class Circle {
<para>Next we implement our method to change a circle's
radius:</para>
- <programlisting> public void setRadius(double r) {
+ <programlisting language="java"> public void setRadius(double r) {
radius = r;
}</programlisting>
@@ -1319,7 +1509,7 @@ public class Circle {
here making it easier for a programmer to recognize the expected
name in the generated javadoc:</para>
- <programlisting> public void setRadius(double radius) {
+ <programlisting language="java"> public void setRadius(double radius) {
<emphasis role="bold">this.</emphasis>radius = radius;
}</programlisting>
@@ -1333,7 +1523,7 @@ public class Circle {
<para>The rest of the implementation is (quite) straightforward.
A complete class reads:</para>
- <programlisting>package step1;
+ <programlisting language="java">package step1;
/**
* A circle of given radius
@@ -1387,9 +1577,13 @@ public class Circle {
</chapter>
<chapter xml:id="sd1CrabsEnhance2">
- <title>Lecture 5 - Enhancing crabs' behaviour II</title>
+ <title>Lecture 5 - Enhancing crabs' behaviour</title>
- <para/>
+ <itemizedlist>
+ <listitem>
+ <para>Read chapter 2 of <xref linkend="bibKoelling2010Ger"/>.</para>
+ </listitem>
+ </itemizedlist>
</chapter>
<chapter xml:id="sd1CrabsFinish">
@@ -1424,7 +1618,7 @@ public class Circle {
<para>A simple implementation to count worms being eaten
reads:</para>
- <programlisting>public class Crab extends Animal {
+ <programlisting language="java">public class Crab extends Animal {
<emphasis role="bold">int noOfWormsEaten = 0; // initially no worm has been eaten</emphasis>
// other methods ...
@@ -1464,7 +1658,7 @@ public class Circle {
solution of <xref linkend="sd1WormEatWorm"/> we need to replace
the <code>if</code> clause by a <code>while</code> loop:</para>
- <programlisting> public void lookForWorm() {
+ <programlisting language="java"> public void lookForWorm() {
<emphasis role="bold">while</emphasis> (canSee(Worm.class)) {
eat(Worm.class);
noOfWormsEaten++;
@@ -1491,7 +1685,7 @@ public class Circle {
<para>Replacing the inner if statement by a switch statement is
straightforward:</para>
- <programlisting>public class Crab extends Animal {
+ <programlisting language="java">public class Crab extends Animal {
// These definitions are not strictly required but do help
// understanding the code
@@ -1550,7 +1744,7 @@ public class Circle {
<para>Implementing a running crab was achieved by introducing two
image objects in Greenfoot/code 4.2 example:</para>
- <programlisting>public class Crab extends Animal {
+ <programlisting language="java">public class Crab extends Animal {
private GreenfootImage image1;
private GreenfootImage image2;
...
@@ -1623,7 +1817,7 @@ public class Circle {
<answer>
<para>A complete implementation reads:</para>
- <programlisting>public class Crab extends Animal {
+ <programlisting language="java">public class Crab extends Animal {
private final static <co
linkends="sd1CrabAnimateStaticImageImplementation-1"
diff --git a/ws/eclipse/Sde1/Figur/src/step1/Driver.java b/ws/eclipse/Sde1/Figur/src/step1/DriverCircle.java
similarity index 94%
rename from ws/eclipse/Sde1/Figur/src/step1/Driver.java
rename to ws/eclipse/Sde1/Figur/src/step1/DriverCircle.java
index f69d06047..0cfc4b56e 100644
--- a/ws/eclipse/Sde1/Figur/src/step1/Driver.java
+++ b/ws/eclipse/Sde1/Figur/src/step1/DriverCircle.java
@@ -1,6 +1,6 @@
package step1;
-public class Driver {
+public class DriverCircle {
public static void main(String[] args) {
Circle c = new Circle(2.3);
diff --git a/ws/eclipse/Sde1/Figur/src/step1/DriverRctangle.java b/ws/eclipse/Sde1/Figur/src/step1/DriverRctangle.java
new file mode 100644
index 000000000..aa66f1e30
--- /dev/null
+++ b/ws/eclipse/Sde1/Figur/src/step1/DriverRctangle.java
@@ -0,0 +1,19 @@
+package step1;
+
+
+public class DriverRctangle {
+
+ public static void main(String[] args) {
+
+ Rectangle r = new Rectangle(8, 5);
+ System.out.println("Perimeter:" + r.getPerimeter());
+ System.out.println("Area:" + r.getArea());
+
+ r.setWidth(4);
+ r.setHeight(7);
+ System.out.println("Perimeter:" + r.getPerimeter());
+ System.out.println("Area:" + r.getArea());
+
+ }
+
+}
diff --git a/ws/eclipse/Sde1/Figur/src/step1/Rectangle.java b/ws/eclipse/Sde1/Figur/src/step1/Rectangle.java
new file mode 100644
index 000000000..4db06de03
--- /dev/null
+++ b/ws/eclipse/Sde1/Figur/src/step1/Rectangle.java
@@ -0,0 +1,61 @@
+package step1;
+
+/**
+ * Representing rectangular shapes.
+ *
+ */
+public class Rectangle {
+
+ // Instance variables representing a rectangle's parameters
+ private double width, height;
+
+ /**
+ *
+ * @param width The rectangle's width
+ * @param heigth The rectangle's height
+ */
+ public Rectangle (double width, double height) {
+ setWidth(width);
+ setHeight(height);
+ }
+ /**
+ * @return The rectangle's area.
+ */
+ public double getArea() {
+ return width * height;
+ }
+
+ /**
+ * @return The rectangle's perimeter.
+ */
+ public double getPerimeter() {
+ return 2 * (width + height);
+ }
+
+ /**
+ * @return The rectangle's width.
+ */
+ public double getWidth() {
+ return width;
+ }
+ /**
+ * @param width The rectangle's new width
+ */
+ public void setWidth(double w) {
+ width = w;
+ }
+
+ /**
+ * @return The rectangle's height.
+ */
+ public double getHeight() {
+ return height;
+ }
+
+ /**
+ * @param width The rectangle's new height
+ */
+ public void setHeight(double height) {
+ this.height = height;
+ }
+}
diff --git a/ws/eclipse/Sde1/Figur/src/step1/dummy/Rectangle.java b/ws/eclipse/Sde1/Figur/src/step1/dummy/Rectangle.java
new file mode 100644
index 000000000..422176489
--- /dev/null
+++ b/ws/eclipse/Sde1/Figur/src/step1/dummy/Rectangle.java
@@ -0,0 +1,57 @@
+package step1.dummy;
+
+/**
+ * Representing rectangular shapes.
+ *
+ */
+public class Rectangle {
+
+ /**
+ *
+ * @param width The rectangle's width
+ * @param heigth The rectangle's height
+ */
+ public Rectangle (double width, double heigth) {
+ //TODO
+ }
+ /**
+ * @return The rectangle's area.
+ */
+ public double getArea() {
+ return 0; // TODO
+ }
+
+ /**
+ * @return The rectangle's perimeter.
+ */
+ public double getPerimeter() {
+ return 0; // TODO
+ }
+
+ /**
+ * @return The rectangle's width.
+ */
+ public double getWidth() {
+ return 0; // TODO
+ }
+ /**
+ * @param width The rectangle's new width
+ */
+ public void setWidth(double width) {
+ // TODO
+ }
+
+ /**
+ * @return The rectangle's height.
+ */
+ public double getHeight() {
+ return 0; // TODO
+ }
+
+ /**
+ * @param width The rectangle's new height
+ */
+ public void setHeight(double height) {
+ // TODO
+ }
+}
diff --git a/ws/eclipse/Sde1/Figur/src/step2/Vector.java b/ws/eclipse/Sde1/Figur/src/step3/Vector.java
similarity index 89%
rename from ws/eclipse/Sde1/Figur/src/step2/Vector.java
rename to ws/eclipse/Sde1/Figur/src/step3/Vector.java
index f21639c14..cf55d5d4c 100644
--- a/ws/eclipse/Sde1/Figur/src/step2/Vector.java
+++ b/ws/eclipse/Sde1/Figur/src/step3/Vector.java
@@ -1,4 +1,4 @@
-package step2;
+package step3;
public class Vector {
--
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