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Issue 259 fixed: combine chapter 4 short chapters #294

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3c923ce
merged sections 4.1-4.4 into one section
habibasorour Jul 30, 2026
443e2ae
moved ternary operator before file handling
habibasorour Jul 30, 2026
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188 changes: 93 additions & 95 deletions source/ch4_conditionals.ptx
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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,7 @@
<chapter xml:id="conditionals">
<title>Conditionals</title>

<section xml:id="simple-if">
<title>Using the Simple <c>if</c> Statement</title>
<section xml:id="using-conditional-in-java"> <title>Using Conditional Statements in Java</title>
<p><idx>conditional statements</idx>
Conditional statements in Python and Java are very similar.
In Python we have three patterns:
Expand Down Expand Up @@ -50,9 +49,9 @@ if score &gt;= 90: # Note the colon at the end of the line
Once again you can see that in Java the curly braces define a block rather than indentation.
In Java, the parentheses around the condition are required because it is technically a function that evaluates to <c>True</c> or <c>False</c>.
</p>
</section>


<section xml:id="use-the-if-else-statement">
<subsection xml:id="use-the-if-else-statement">
<title>Using the <c>if</c> - <c>else</c> Statement</title>

<p><xref ref= "python-if-else" text="type-global"/> shows how the <c>if</c> - <c>else</c>statement is written in Python.</p>
Expand Down Expand Up @@ -85,9 +84,9 @@ if score &gt;= 90: # Note the colon at the end of the line
</code>
</program>
</listing>
</section>
</subsection>

<section xml:id="elif">
<subsection xml:id="elif">
<title>Can we use <c>elif</c>?</title>

<p><idx><c>elif</c> statement</idx>
Expand Down Expand Up @@ -172,9 +171,9 @@ public class ElseIf {
</code> <tests> </tests>
</program>
</listing>
</section>
</subsection>

<section xml:id="switch">
<subsection xml:id="switch">
<title>Using the <c>switch</c> Statement</title>

<p>
Expand Down Expand Up @@ -255,9 +254,94 @@ The <c>switch</c> statement is not used very often, and we recommend you do not
</p>
<p>
Finally, the <c>switch</c> statement does not support relational expressions such as greater than or less than. So you cannot use it to completely replace the <c>elif</c>. Even with the new features of Java 14+ the <c>switch</c> statement is still limited to constant comparisons using equality.</p>
</subsection>
</section>

<section xml:id="exception-handling">
<section xml:id="ternary-operator">
<title>The Ternary Operator</title>

<p><idx>Boolean operators</idx> <idx>simple comparisons</idx> <idx>compound Boolean expressions</idx>
The conditionals used in the if statement can be <term>Boolean variables</term>, <term>simple comparisons</term>, and <term>compound Boolean expressions</term>.
</p>

<p><idx>ternary operator</idx>
Java also provides the ternary operator <c>condition ? valueIfTrue : valueIfFalse</c>, which lets you use a <c>boolean</c> test directly inside an assignment. If the condition is true, the first value is chosen; otherwise, the second value is used. <xref ref="ternary-operator-table" text="type-global"/> summarizes how it works.
</p>

<table xml:id="ternary-operator-table">
<title>Ternary Operator in Java</title>
<tabular>
<row>
<cell><term>Component</term></cell>
<cell><term>Description</term></cell>
</row>
<row>
<cell><c>condition</c></cell>
<cell>The <c>boolean</c> expression that is evaluated (e.g., <c>a % 2 == 0</c>).</cell>
</row>
<row>
<cell><c>?</c></cell>
<cell> This is the ternary operator that separates the condition from the <c>trueValue</c>.</cell>
</row>
<row>
<cell><c>trueValue</c></cell>
<cell>The value assigned if the condition is true (e.g., <c>a * a</c>).</cell>
</row>
<row>
<cell><c>:</c></cell>
<cell> This is the ternary operator that separates the <c>trueValue</c> from the <c>falseValue</c>.</cell>
</row>
<row>
<cell><c>falseValue</c></cell>
<cell>The value assigned if the condition is false (e.g., <c>3 * x - 1</c>).</cell>
</row>
<row>
<cell>Example Usage</cell>
<cell><c>a = a % 2 == 0 ? a * a : 3 * x - 1</c></cell>
</row>
<row>
<cell>Equivalent if-else Code</cell>
<cell>Can also be written with a regular <c>if-else</c> statement, but the ternary form is more concise.</cell>
</row>
</tabular>
</table>

<p>
Using this operator can make code shorter and more readable in cases where a simple conditional assignment is needed. <xref ref="java-ternary" text="type-global"/> shows an example where we see the same logic implemented in two different ways.
</p>
<listing xml:id="java-ternary">
<program interactive="activecode" language ="java">
<code>
public class Ternary {
public static void main(String[] args) {
int a = 4;
int x = 2;
int outp;

// ternary:
outp = (a % 2 == 0) ? (a * a) : (3 * x - 1);
System.out.println("ternary result: " + outp);

// Equivalent using if/else
if (a % 2 == 0) {
outp = a * a;
} else {
outp = 3 * x - 1;
}

System.out.println("if/else result: " + outp);
}
}
</code>
</program>
</listing>

<p>
In <xref ref="java-ternary" text="type-global"/>, we are using this ternary operator to assign a value to <c>a</c> based on whether <c>a</c> is even or odd. If <c>a</c> is even, it will be squared; if odd, it will be instead be calculated as <c>3 * x - 1</c>. This is a concise way to write conditional assignments in Java. However, you might want to use it sparingly, as it can make code less readable if overused or used with complex expressions.
</p>
</section>

<section xml:id="exception-handling">
<title>Exception Handling</title>

<p>
Expand Down Expand Up @@ -411,92 +495,6 @@ The <c>switch</c> statement is not used very often, and we recommend you do not
Note that as with other structures in Java, <c>try-catch</c> blocks blocks must be encased with braces <c>{}</c>. The most important part of this code is, after <c>catch</c>, there is a set of parenthesis with an exception type and a variable name <c>catch (InputMismatchException e)</c>. This is where we declare a <c>InputMismatchException</c> exception and name it with the variable name <c>e</c>. It is common practice, though not a requirement, to name exception variables <c>e</c> in this manner.
</p>

</section>

<section xml:id="ternary-operator">
<title>The Ternary Operator</title>

<p><idx>Boolean operators</idx> <idx>simple comparisons</idx> <idx>compound Boolean expressions</idx>
The conditionals used in the if statement can be <term>Boolean variables</term>, <term>simple comparisons</term>, and <term>compound Boolean expressions</term>.
</p>

<p><idx>ternary operator</idx>
Java also provides the ternary operator <c>condition ? valueIfTrue : valueIfFalse</c>, which lets you use a <c>boolean</c> test directly inside an assignment. If the condition is true, the first value is chosen; otherwise, the second value is used. <xref ref="ternary-operator-table" text="type-global"/> summarizes how it works.
</p>

<table xml:id="ternary-operator-table">
<title>Ternary Operator in Java</title>
<tabular>
<row>
<cell><term>Component</term></cell>
<cell><term>Description</term></cell>
</row>
<row>
<cell><c>condition</c></cell>
<cell>The <c>boolean</c> expression that is evaluated (e.g., <c>a % 2 == 0</c>).</cell>
</row>
<row>
<cell><c>?</c></cell>
<cell> This is the ternary operator that separates the condition from the <c>trueValue</c>.</cell>
</row>
<row>
<cell><c>trueValue</c></cell>
<cell>The value assigned if the condition is true (e.g., <c>a * a</c>).</cell>
</row>
<row>
<cell><c>:</c></cell>
<cell> This is the ternary operator that separates the <c>trueValue</c> from the <c>falseValue</c>.</cell>
</row>
<row>
<cell><c>falseValue</c></cell>
<cell>The value assigned if the condition is false (e.g., <c>3 * x - 1</c>).</cell>
</row>
<row>
<cell>Example Usage</cell>
<cell><c>a = a % 2 == 0 ? a * a : 3 * x - 1</c></cell>
</row>
<row>
<cell>Equivalent if-else Code</cell>
<cell>Can also be written with a regular <c>if-else</c> statement, but the ternary form is more concise.</cell>
</row>
</tabular>
</table>

<p>
Using this operator can make code shorter and more readable in cases where a simple conditional assignment is needed. <xref ref="java-ternary" text="type-global"/> shows an example where we see the same logic implemented in two different ways.
</p>
<listing xml:id="java-ternary">
<program interactive="activecode" language ="java">
<code>
public class Ternary {
public static void main(String[] args) {
int a = 4;
int x = 2;
int outp;

// ternary:
outp = (a % 2 == 0) ? (a * a) : (3 * x - 1);
System.out.println("ternary result: " + outp);

// Equivalent using if/else
if (a % 2 == 0) {
outp = a * a;
} else {
outp = 3 * x - 1;
}

System.out.println("if/else result: " + outp);
}
}
</code>
</program>
</listing>

<p>
In <xref ref="java-ternary" text="type-global"/>, we are using this ternary operator to assign a value to <c>a</c> based on whether <c>a</c> is even or odd. If <c>a</c> is even, it will be squared; if odd, it will be instead be calculated as <c>3 * x - 1</c>. This is a concise way to write conditional assignments in Java. However, you might want to use it sparingly, as it can make code less readable if overused or used with complex expressions.
</p>


</section>
<section xml:id="chapter4_summary">
<title>Summary &amp; Reading Questions</title>
Expand Down