From de31c19f788a49470ed8501cbac64e15e178d72b Mon Sep 17 00:00:00 2001
From: Martin Goik <goik@hdm-stuttgart.de>
Date: Sat, 26 Apr 2014 16:33:23 +0200
Subject: [PATCH] Secon leap year variant, minor extension to MathTable
---
.../hdm_stuttgart/de/sd1/leap/LeapYear.java | 5 ++--
.../de/sd1/leap/LeapYearCompact.java | 24 +++++++++++++++++
.../de/sd1/rounding/MathTable.java | 26 ++++++++++---------
Sd1/swd1.xml | 24 +++++++++++++++++
4 files changed, 65 insertions(+), 14 deletions(-)
create mode 100644 Sd1/P/rounding/src/main/java/de/hdm_stuttgart/de/sd1/leap/LeapYearCompact.java
diff --git a/Sd1/P/rounding/src/main/java/de/hdm_stuttgart/de/sd1/leap/LeapYear.java b/Sd1/P/rounding/src/main/java/de/hdm_stuttgart/de/sd1/leap/LeapYear.java
index ed9ab7c84..bdaecebbc 100644
--- a/Sd1/P/rounding/src/main/java/de/hdm_stuttgart/de/sd1/leap/LeapYear.java
+++ b/Sd1/P/rounding/src/main/java/de/hdm_stuttgart/de/sd1/leap/LeapYear.java
@@ -16,9 +16,10 @@ public class LeapYear {
* @return true if year is a leap year, false otherwise.
*/
public static boolean isLeapYear(int year) {
- if (year % 400 == 0 ||
- year % 4 == 0 && 0 != year % 200){
+ if (year % 400 == 0) { // Every 400 years we do have a leap year.
return true;
+ } else if (year % 4 == 0 && 0 != year % 200) { // Every 4 years we do have a leap year unless the year
+ return true; // in question is a multiple of 100.
} else {
return false;
}
diff --git a/Sd1/P/rounding/src/main/java/de/hdm_stuttgart/de/sd1/leap/LeapYearCompact.java b/Sd1/P/rounding/src/main/java/de/hdm_stuttgart/de/sd1/leap/LeapYearCompact.java
new file mode 100644
index 000000000..4a9b8b1a8
--- /dev/null
+++ b/Sd1/P/rounding/src/main/java/de/hdm_stuttgart/de/sd1/leap/LeapYearCompact.java
@@ -0,0 +1,24 @@
+package de.hdm_stuttgart.de.sd1.leap;
+
+public class LeapYearCompact {
+
+ public static void main(String[] args) {
+ System.out.println("Is 1800 a leap year? " + isLeapYear(1800));
+ System.out.println("Is 2000 a leap year? " + isLeapYear(2000));
+ System.out.println("Is 2016 a leap year? " + isLeapYear(2016));
+ }
+
+ /**
+ * Characterizing a given year either as leap year or
+ * non- leap year
+ *
+ * @param year The year in question.
+ * @return true if year is a leap year, false otherwise.
+ */
+ public static boolean isLeapYear(int year) {
+ return
+ year % 400 == 0 || // Every 400 years we do have a leap year.
+ year % 4 == 0 && 0 != year % 200; // Every 4 years we do have a leap year unless the year
+ // in question is a multiple of 100.
+ }
+}
diff --git a/Sd1/P/rounding/src/main/java/de/hdm_stuttgart/de/sd1/rounding/MathTable.java b/Sd1/P/rounding/src/main/java/de/hdm_stuttgart/de/sd1/rounding/MathTable.java
index c2b35fc8b..e993ffb0c 100644
--- a/Sd1/P/rounding/src/main/java/de/hdm_stuttgart/de/sd1/rounding/MathTable.java
+++ b/Sd1/P/rounding/src/main/java/de/hdm_stuttgart/de/sd1/rounding/MathTable.java
@@ -12,10 +12,12 @@ public class MathTable {
System.out.println("----+------");
for (int i = 0; i < 360; i += 5) {
- final long precision = 1000,// Rounding three decimal places
- sinValueRounded = Math.round(precision *
- Math.sin(i * Math.PI / 180)), // Turning degrees to radians
- digit = sinValueRounded / precision;
+ final double
+ sinValue = Math.sin(i * Math.PI / 180); // Turning degrees into radians
+ final long
+ precision = 1000,// Rounding to three decimal places
+ sinValueRounded = Math.round(precision * sinValue),
+ digits = sinValueRounded / precision;
long fraction = sinValueRounded % precision;
@@ -27,22 +29,22 @@ public class MathTable {
if (fraction < 0) {
fraction *= -1;
- System.out.print(i + " |-" + digit + ".");
- } else if (-1 < digit){
- System.out.print(i + " | " + digit + ".");
+ System.out.print(i + " |-" + digits + ".");
+ } else if (-1 < digits){
+ System.out.print(i + " | " + digits + ".");
} else {
- System.out.print(i + " |" + digit + ".");
+ System.out.print(i + " |" + digits + ".");
}
- if (fraction < 9) { // Padding fraction with zeros
- System.out.print("00"); // One digit, add two zeros
+ if (fraction < 9) { // Padding fraction with zeros if required
+ System.out.print("00"); // One digit, add two leading zeros
} else if (fraction < 99) {
- System.out.print("0"); // Two digits, add two zeros
+ System.out.print("0"); // Two digits, add one leading zero
}
System.out.println(fraction);
- if (0 < i && 0 == i % 20) {
+ if (0 < i && 0 == i % 20) { // Add extra seperator every four lines
System.out.println("----+------");
}
}
diff --git a/Sd1/swd1.xml b/Sd1/swd1.xml
index 5e386d1f8..13764545d 100644
--- a/Sd1/swd1.xml
+++ b/Sd1/swd1.xml
@@ -2663,6 +2663,30 @@ Is 2016 a leap year? true</programlisting>
</question>
<answer>
+ <para>A first solution may be:</para>
+
+ <programlisting language="java"> <link
+ xlink:href="Ref/api/P/rounding/src-html/de/hdm_stuttgart/de/sd1/leap/LeapYear.html">public static boolean isLeapYear(int year)</link> {
+ if (year % 400 == 0) { // Every 400 years we do have a leap year.
+ return true;
+ } else if (year % 4 == 0 && 0 != year % 200) { // Every 4 years we do have a leap year unless the year
+ return true; // in question is a multiple of 100.
+ } else {
+ return false;
+ }
+ }</programlisting>
+
+ <para>This one is easy to read. Experienced programmers
+ however prefer compact code:</para>
+
+ <programlisting language="java"> <link
+ xlink:href="Ref/api/P/rounding/src-html/de/hdm_stuttgart/de/sd1/leap/LeapYearCompact.html">public static boolean isLeapYear(int year)</link> {
+ return
+ year % 400 == 0 || // Every 400 years we do have a leap year.
+ year % 4 == 0 && 0 != year % 200; // Every 4 years we do have a leap year unless the year
+ // in question is a multiple of 100.
+ } </programlisting>
+
<para>See <link
xlink:href="Ref/api/P/rounding/src-html/de/hdm_stuttgart/de/sd1/leap/LeapYear.html">LeapYear</link>.</para>
</answer>
--
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