diff --git a/Doc/Sd1/Inheritance/inheritance.xml b/Doc/Sd1/Inheritance/inheritance.xml
index 3b6bb206a37ae38665900b180d55a96c753a30ce..896748445bd80a94c9d206c34fd321011f8da6c8 100644
--- a/Doc/Sd1/Inheritance/inheritance.xml
+++ b/Doc/Sd1/Inheritance/inheritance.xml
@@ -431,26 +431,25 @@ public <link
</figure>
<qandaset defaultlabel="qanda" xml:id="sd1_qanda_stringEqualProblem">
- <title>Let me in, please!</title>
+ <title>Let me pass, please!</title>
<qandadiv>
<qandaentry>
<question>
<para>Consider the following snippet:</para>
- <programlisting language="java">try (final Scanner scan = new Scanner(System.in)) {
- do {
- System.out.print("Please enter password: ");
- final String password = scan.nextLine();
- if (password == "secret") {
- break; // Leave enclosing do ... while loop
- } else {
- System.out.println("Sorry, please try again");
- }
- } while (true);
+ <programlisting language="java">final Scanner scan = new Scanner(System.in));
+do {
+ System.out.print("Please enter password: ");
+ final String password = scan.nextLine();
+ if (password == "secret") {
+ break; // Leave enclosing do ... while loop
+ } else {
+ System.out.println("Sorry, please try again");
+ }
+} while (true);
System.out.println("You made it!");
- // ...
-}</programlisting>
+ // ...</programlisting>
<para>Describe the above code's intended behaviour. Will it
succeed? Execute the above code and provide a clue for correcting
@@ -476,41 +475,42 @@ public <link
xlink:href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/String.html">String</classname>
object in memory as well.</para>
- <para>Unfortunately the usual <quote>==</quote> operator only
- works as expected for the eight built in primitive <xref
- linkend="glo_Java"/> types. With respect to class instances a
- variable holds a reference to an object rather than the object
- itself. Applying the <quote>==</quote> operator compares for
- object identity rather than object equality.</para>
+ <para>Unfortunately the <quote>==</quote> operator only works as
+ expected for the eight built in primitive <xref
+ linkend="glo_Java"/> types. With respect to class instances
+ variables hold references to objects rather than to the objects'
+ values. The <quote>==</quote> operator compares for object
+ identity rather than for object equality.</para>
<para>Two different <classname
xlink:href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/String.html">String</classname>
- instances albeit being different object instances may off course
- be equal with respect to their <quote>payload</quote> namely the
- strings they both represent. Comparing for object equality rather
- than for object identity in <xref linkend="glo_Java"/> requires
+ instances may off course be equal with respect to their
+ <quote>payload</quote> namely the values they both represent.
+ Comparing for object equality rather than for object identity in
+ <xref linkend="glo_Java"/> requires using the
+ <methodname>equals(...)</methodname> method instead. A
+ prerequisite for this to work requires the class authors
overriding the <methodname
xlink:href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/Object.html#equals(java.lang.Object)">Object.equals(Object
- o)</methodname> method. This override does exist in class
- <classname
+ o)</methodname> method accordingly. This override does exist in
+ class <classname
xlink:href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/String.html">String</classname>.
Within the given context we may thus simply use <methodname
xlink:href="https://docs.oracle.com/en/java/javase/17/docs/api/java.base/java/lang/String.html#equals(java.lang.Object)">String.equals(Object
o)</methodname>:</para>
- <programlisting language="none">try (final Scanner scan = new Scanner(System.in)) {
- do {
- System.out.print("Please enter password: ");
- final String password = scan.nextLine();
- <emphasis role="red">if (password.equals("secret"))</emphasis> {
- break; // Leave enclosing do ... while loop
- } else {
- System.out.println("Sorry, please try again");
- }
- } while (true);
- System.out.println("You made it!");
- // ...
-}</programlisting>
+ <programlisting language="none">final Scanner scan = new Scanner(System.in));
+do {
+ System.out.print("Please enter password: ");
+ final String password = scan.nextLine();
+ <emphasis role="red">if (password.equals("secret"))</emphasis> {
+ break; // Leave enclosing do ... while loop
+ } else {
+ System.out.println("Sorry, please try again");
+ }
+} while (true);
+System.out.println("You made it!");
+// ...</programlisting>
</answer>
</qandaentry>
</qandadiv>
diff --git a/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/EnterIntValue.java b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/EnterIntValue.java
index 60a125b6a816003fc66b6b0f34143f99b0cb6b3c..2b12b3ee7eddcc50c3b18adbf01ededa795ce6df 100644
--- a/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/EnterIntValue.java
+++ b/Doc/Sd1/Ref/WorkingWithNumbers/P/src/main/java/de/hdm_stuttgart/sd1/EnterIntValue.java
@@ -3,7 +3,6 @@ package de.hdm_stuttgart.sd1;
import java.util.Scanner;
public class EnterIntValue {
-
public static void main(String[] args) {
String userInput = null;
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
index d930a381fe783f8898319629bc27336353d39079..f5e66a135b08e29b6b8b3162897675f400c53f88 100644
--- 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
@@ -7,20 +7,14 @@ 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);
+ final Random generator = new Random(seed);
for (int i = 0; i < 10; i++) {
System.out.print(generator.nextBoolean() + " ");
}
}
-
}
-
-
-
-
}
diff --git a/Doc/Sd1/Statements/statements.xml b/Doc/Sd1/Statements/statements.xml
index c8e5ed8d441ee289dbb7551425c7c4e571b1d87a..3b5841559a0f762288f6dee8b718af37f9b98b12 100644
--- a/Doc/Sd1/Statements/statements.xml
+++ b/Doc/Sd1/Statements/statements.xml
@@ -851,19 +851,16 @@ else
<tr>
<td valign="top"><programlisting language="java">import java.util.Scanner;
+
public class App {
public static void main(String[] args){
- try (final Scanner scan =
- new Scanner(System.in)) {
-
- System.out.print("Enter a value:");
-
- final int value = scan.nextInt();
-
- System.out.println(
- "You entered " + value);
- }
+ final Scanner scan =
+ new Scanner(System.in));
+ System.out.print("Enter a value:");
+ final int value = scan.nextInt();
+ System.out.println("You entered "
+ + value);
}
}</programlisting></td>
@@ -1239,34 +1236,33 @@ Decimal value 11 not yet implemented</screen>
</question>
<answer>
- <para><programlisting language="java">try (final Scanner scan = new Scanner(System.in)) {
-
- System.out.print("Enter a number:>");
- final int number = scan.nextInt();
-
- if (1 == number) {
- System.out.println("I");
- } else if (2 == number) {
- System.out.println("II");
- } else if (3 == number) {
- System.out.println("III");
- } else if (4 == number) {
- System.out.println("IV");
- } else if (5 == number) {
- System.out.println("V");
- } else if (6 == number) {
- System.out.println("VI");
- } else if (7 == number) {
- System.out.println("VII");
- } else if (8 == number) {
- System.out.println("VIII");
- } else if (9 == number) {
- System.out.println("IX");
- } else if (10 == number) {
- System.out.println("X");
- } else {
- System.out.println("Decimal value " + number + " not yet implemented");
- }
+ <para><programlisting language="java">final Scanner scan = new Scanner(System.in));
+
+System.out.print("Enter a number:>");
+final int number = scan.nextInt();
+
+if (1 == number) {
+ System.out.println("I");
+} else if (2 == number) {
+ System.out.println("II");
+} else if (3 == number) {
+ System.out.println("III");
+} else if (4 == number) {
+ System.out.println("IV");
+} else if (5 == number) {
+ System.out.println("V");
+} else if (6 == number) {
+ System.out.println("VI");
+} else if (7 == number) {
+ System.out.println("VII");
+} else if (8 == number) {
+ System.out.println("VIII");
+} else if (9 == number) {
+ System.out.println("IX");
+} else if (10 == number) {
+ System.out.println("X");
+} else {
+ System.out.println("Decimal value " + number + " not yet implemented");
}</programlisting></para>
</answer>
</qandaentry>
@@ -1335,22 +1331,21 @@ Decimal value 11 not yet implemented</screen>
<figure xml:id="sd1_fig_dayNumber2NameByIfElseif">
<title>Numbers to day's names: The hard way</title>
- <programlisting language="java">try (final Scanner scan = new Scanner(System.in)) {
- System.out.print("Enter a weekday number (1=Monday, 2=Tuesday,...) : ");
+ <programlisting language="java">final Scanner scan = new Scanner(System.in));
+System.out.print("Enter a weekday number (1=Monday, 2=Tuesday,...) : ");
- final int number = scan.nextInt();
+final int number = scan.nextInt();
- if (1 == number) {
- System.out.println("Monday");
- } else if (2 == number) {
- System.out.println("Tuesday");
+if (1 == number) {
+ System.out.println("Monday");
+} else if (2 == number) {
+ System.out.println("Tuesday");
...
- } else if (7 == number) {
- System.out.println("Sunday");
- } else {
- System.out.println("Invalid number " + number);
- }
+} else if (7 == number) {
+ System.out.println("Sunday");
+} else {
+ System.out.println("Invalid number " + number);
}</programlisting>
</figure>
@@ -1390,24 +1385,23 @@ import java.util.Scanner;
public class LeapYear {
- public static void main(String[] args) {
+ public static void main(String[] args) {
- try (final Scanner scan = new Scanner(System.in)) {
+ final Scanner scan = new Scanner(System.in));
- System.out.print("Enter a year:>");
- final int year = scan.nextInt();
+ System.out.print("Enter a year:>");
+ final int year = scan.nextInt();
- if (0 == year % 400) { <emphasis role="bold"> // Every 400 years we do have a leap year.</emphasis>
- System.out.println(
- "Year " + year + " is a leap year");
- } else if (0 == year % 4 && <emphasis role="bold"> // Every 4 years we do have a leap year</emphasis>
- 0 != year % 100) { <emphasis role="bold"> // unless year is a multiple of 100.</emphasis>
- System.out.println("Year " + year + " is a leap year");
- } else {
- System.out.println("Year " + year + " is no leap year");
- }
+ if (0 == year % 400) { <emphasis role="bold"> // Every 400 years we do have a leap year.</emphasis>
+ System.out.println(
+ "Year " + year + " is a leap year");
+ } else if (0 == year % 4 && <emphasis role="bold"> // Every 4 years we do have a leap year</emphasis>
+ 0 != year % 100) { <emphasis role="bold"> // unless year is a multiple of 100.</emphasis>
+ System.out.println("Year " + year + " is a leap year");
+ } else {
+ System.out.println("Year " + year + " is no leap year");
}
- }
+ }
}</programlisting>
<para>This solution contains two identical <code
@@ -1419,10 +1413,10 @@ public class LeapYear {
<programlisting language="java">public static void main(String[] args) {
...
- if (0 == year % 400 || <emphasis role="bold">// Every 400 years we do have a leap year.</emphasis>
+ if (0 == year % 400 || <emphasis role="bold">// Every 400 years we do have a leap year.</emphasis>
(0 == year % 4 && <emphasis role="bold">// Every 4 years we do have a leap year</emphasis>
0 != year % 100)) { <emphasis role="bold">// unless year is a multiple of 100.</emphasis>
- System.out.println("Year " + year + " is a leap year");
+ System.out.println("Year " + year + " is a leap year");
} else {
System.out.println("Year " + year + " is no leap year");
}
@@ -1509,20 +1503,19 @@ Saturday</screen>
<para><xref linkend="sd1_fig_dayNumber2NameByIfElseif"/> can be
rewritten as:</para>
- <programlisting language="java">try (final Scanner scan = new Scanner(System.in)) {
- System.out.print("Enter a weekday number (1=Monday, 2=Tuesday,...) : ");
- final int number = scan.nextInt();
- switch(number) {
- case 1: System.out.println("Monday");
- case 2: System.out.println("Tuesday");
- case 3: System.out.println("Wednesday");
- case 4: System.out.println("Thursday");
- case 5: System.out.println("Friday");
- case 6: System.out.println("Saturday");
- case 7: System.out.println("Sunday");
-
- default: System.out.println("Invalid number " + number);
- }
+ <programlisting language="java">final Scanner scan = new Scanner(System.in));
+System.out.print("Enter a weekday number (1=Monday, 2=Tuesday,...) : ");
+final int number = scan.nextInt();
+switch(number) {
+ case 1: System.out.println("Monday");
+ case 2: System.out.println("Tuesday");
+ case 3: System.out.println("Wednesday");
+ case 4: System.out.println("Thursday");
+ case 5: System.out.println("Friday");
+ case 6: System.out.println("Saturday");
+ case 7: System.out.println("Sunday");
+
+ default: System.out.println("Invalid number " + number);
}</programlisting>
<para>Entering a day's number 5 yields:</para>
@@ -1765,20 +1758,19 @@ Unknown day name 'July'</screen>
</question>
<answer>
- <programlisting language="java">try (final Scanner scan = new Scanner(System.in)) {
- System.out.print("Enter a weekday (Monday to Sunday):>");
- final String day = scan.next();
- switch(day) {
- case "Monday": System.out.println(1); break;
- case "Tuesday": System.out.println(2); break;
- case "Wednesday": System.out.println(3); break;
- case "Thursday": System.out.println(4); break;
- case "Friday": System.out.println(5); break;
- case "Saturday": System.out.println(6); break;
- case "Sunday": System.out.println(7); break;
- default: System.out.println("Unknown day name '" + day + "'");
- break;
- }
+ <programlisting language="java">final Scanner scan = new Scanner(System.in));
+System.out.print("Enter a weekday (Monday to Sunday):>");
+final String day = scan.next();
+switch(day) {
+ case "Monday": System.out.println(1); break;
+ case "Tuesday": System.out.println(2); break;
+ case "Wednesday": System.out.println(3); break;
+ case "Thursday": System.out.println(4); break;
+ case "Friday": System.out.println(5); break;
+ case "Saturday": System.out.println(6); break;
+ case "Sunday": System.out.println(7); break;
+ default: System.out.println("Unknown day name '" + day + "'");
+ break;
}</programlisting>
</answer>
</qandaentry>
@@ -1851,23 +1843,22 @@ Midweek</screen>
</question>
<answer>
- <programlisting language="java">try (final Scanner scan = new Scanner(System.in)) {
- System.out.print("Enter a weekday (Monday to Sunday):>");
- final String day = scan.next();
- switch(day) {
- case "Monday": System.out.println("Start of work week"); break;
+ <programlisting language="java">final Scanner scan = new Scanner(System.in));
+System.out.print("Enter a weekday (Monday to Sunday):>");
+final String day = scan.next();
+switch(day) {
+ case "Monday": System.out.println("Start of work week"); break;
- case "Tuesday":
- case "Wednesday":
- case "Thursday": System.out.println("Midweek"); break;
+ case "Tuesday":
+ case "Wednesday":
+ case "Thursday": System.out.println("Midweek"); break;
- case "Friday": System.out.println("End of work week"); break;
+ case "Friday": System.out.println("End of work week"); break;
- case "Saturday":
- case "Sunday": System.out.println("Weekend"); break;
+ case "Saturday":
+ case "Sunday": System.out.println("Weekend"); break;
- default: System.out.println("Unknown day name " + day); break;
- }
+ default: System.out.println("Unknown day name " + day); break;
}</programlisting>
</answer>
</qandaentry>
@@ -1886,26 +1877,25 @@ Midweek</screen>
</question>
<answer>
- <para><programlisting language="java">try (final Scanner scan = new Scanner(System.in)) {
-
- System.out.print("Enter a number:>");
- final int number = scan.nextInt();
-
- switch (number) {
- case 1: System.out.println("I"); break;
- case 2: System.out.println("II"); break;
- case 3: System.out.println("III"); break;
- case 4: System.out.println("IV"); break;
- case 5: System.out.println("V"); break;
- case 6: System.out.println("VI"); break;
- case 7: System.out.println("VII"); break;
- case 8: System.out.println("VIII"); break;
- case 9: System.out.println("IX"); break;
- case 10: System.out.println("X"); break;
-
- default:System.out.println("Decimal value " + number + " not yet implemented");
- break;
- }
+ <para><programlisting language="java">final Scanner scan = new Scanner(System.in));
+
+System.out.print("Enter a number:>");
+final int number = scan.nextInt();
+
+switch (number) {
+ case 1: System.out.println("I"); break;
+ case 2: System.out.println("II"); break;
+ case 3: System.out.println("III"); break;
+ case 4: System.out.println("IV"); break;
+ case 5: System.out.println("V"); break;
+ case 6: System.out.println("VI"); break;
+ case 7: System.out.println("VII"); break;
+ case 8: System.out.println("VIII"); break;
+ case 9: System.out.println("IX"); break;
+ case 10: System.out.println("X"); break;
+
+ default:System.out.println("Decimal value " + number + " not yet implemented");
+ break;
}</programlisting></para>
</answer>
</qandaentry>
@@ -2183,20 +2173,19 @@ while (counter++ < 10) {
<answer>
<programlisting language="java">public static void main(String[] args) {
- try (final Scanner scan = new Scanner(System.in)) {
+ final Scanner scan = new Scanner(System.in));
- System.out.print("Enter an integer value: ");
- final int value = scan.nextInt();
+ System.out.print("Enter an integer value: ");
+ final int value = scan.nextInt();
- long factorial = 1;
- int i = 1;
-
- while (i++ < value) {
- factorial *= i;
- }
+ long factorial = 1;
+ int i = 1;
- System.out.println(value + "! == " + factorial);
+ while (i++ < value) {
+ factorial *= i;
}
+
+ System.out.println(value + "! == " + factorial);
}</programlisting>
</answer>
</qandaentry>
@@ -2285,7 +2274,7 @@ Goodbye!</screen>A <code language="java">do ... while(...)</code> rather than
a <code language="java">while(...)</code> loop is thus
appropriate. It allows for entering the loop's body <emphasis
role="bold">before</emphasis> any check is about to
- happen:<programlisting language="java">try(final Scanner scanner = new Scanner(System.in)){
+ happen:<programlisting language="java">final Scanner scanner = new Scanner(System.in));
int userInput;
do {
@@ -2456,21 +2445,20 @@ It's square is 1.9999999999999996</screen>
</m:math>
</inlineequation> respectively:</para>
- <programlisting language="java">try (final Scanner scan = new Scanner(System.in)) {
+ <programlisting language="java">final Scanner scan = new Scanner(System.in));
- System.out.print("Enter a non-negative value: ");
- final double a = scan.nextDouble();
+System.out.print("Enter a non-negative value: ");
+final double a = scan.nextDouble();
- double x_next = a / 2, x_current;
+double x_next = a / 2, x_current;
- do {
- x_current = x_next; // Save current approximation value
- x_next = (x_current + a / x_current) / 2; // Calculate next series value
- } while (x_next != x_current); // Did we get any closer?
+do {
+ x_current = x_next; // Save current approximation value
+ x_next = (x_current + a / x_current) / 2; // Calculate next series value
+} while (x_next != x_current); // Did we get any closer?
- System.out.println("The square root of " + a + " is close to " + x_next);
- System.out.println("It's square is " + x_next * x_next);
-}</programlisting>
+System.out.println("The square root of " + a + " is close to " + x_next);
+System.out.println("It's square is " + x_next * x_next);</programlisting>
</answer>
</qandaentry>
</qandadiv>
@@ -5455,26 +5443,26 @@ System.out.println("Try to guess my secret number in between 0 and "
System.out.println("You have " + numOfUserAttempts + " attempts");
-try (final Scanner scan = new Scanner(System.in)) {
- boolean numberWasFound = false;
+final Scanner scan = new Scanner(System.in));
+boolean numberWasFound = false;
- for (int i = 0; i < numOfUserAttempts; i++) {
- System.out.print("Input your guess:");
- final int userGuess = scan.nextInt();
- if (userGuess < randomValue) {
- System.out.println("Number is too low");
- } else if (randomValue < userGuess) {
- System.out.println("Number is too high");
- } else {
- numberWasFound = true;
- break;
- }
- }
- if (numberWasFound) {
- System.out.println("Congratulations, you won!");
- } else {
- System.out.println("Game over, try another run?");
- }
+for (int i = 0; i < numOfUserAttempts; i++) {
+ System.out.print("Input your guess:");
+ final int userGuess = scan.nextInt();
+ if (userGuess < randomValue) {
+ System.out.println("Number is too low");
+ } else if (randomValue < userGuess) {
+ System.out.println("Number is too high");
+ } else {
+ numberWasFound = true;
+ break;
+ }
+}
+
+if (numberWasFound) {
+ System.out.println("Congratulations, you won!");
+} else {
+ System.out.println("Game over, try another run?");
}</programlisting>
<para>In case you don't like <code>break</code> statements the