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2022-02-15 01:14:58 -05:00
<meta name="author" content="Brandon Rozek">
2020-01-15 23:07:02 -05:00
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<h1>Lecture for February 8th</h1>
<h2>Switch Statements</h2>
<p>Another way to perform multiway branching. Comparing a variable and constant values (<code>String</code>, <code>int</code>, <code>char</code>)</p>
<p>Switch statements cannot be used with <code>boolean</code>, <code>double</code>, or <code>float</code>s</p>
<h3>Syntax</h3>
<pre><code class="language-java">switch (variable) {
case value1:
// Do something
break;
case value2:
// Do something else
break;
//...
default:
// If all else fails do this
break;
}</code></pre>
<p><code>case</code> is a reserved word that means &quot;when our variable in consideration is equal to...&quot;</p>
<p>If you forget the <code>break</code> keyword, then the program will keep doing the work of all the statements until it hits a <code>break</code> keyword.</p>
<h3>Example Switch Syntax</h3>
<pre><code class="language-java">switch (birthday) {
case 1:
birthstone = "garnet";
break;
case 2:
birthstone = "amethyst";
break;
// ....
default:
System.out.println("Not valid");
break;
}</code></pre>
<h2>Comparing Strings Relationally</h2>
<p>Comparing strings are based on the ASCII value of characters</p>
<p>Sorting strings will result in strings being in alphabetical or reverse alphabetical order. The values of the strings are compared character by character from the left with each ASCII value.</p>
<p>To compare strings use the <code>compareTo()</code> method. Here is the format of the call</p>
<pre><code class="language-java">str1.compareTo(str2)</code></pre>
<p>This returns a <em>negative number</em> when <code>str1</code> is less than <code>str2</code></p>
<p>This returns <code>0</code> when <code>str1</code> is equal to <code>str1</code></p>
<p>This returns a <em>positive number</em> when <code>str1</code> is greater than <code>str2</code></p>
<h3>Example</h3>
<pre><code class="language-java">String a = "apple";
String b = "banana";
int x = a.compareTo(b); // x = -1
int y = b.compareTo(a); // y = 1</code></pre>
<h2>Ternary Operator</h2>
<p>With a ternary operator, you can shorten statements where a value is determined by an if statement</p>
<pre><code class="language-java">String output = "";
if (movieRating &gt; 4) {
output = "Fan favorite";
} else {
output = "Alright";
}</code></pre>
<p>Is equivalent to</p>
<pre><code class="language-java">String output = "";
output = (movieRating &gt; 4)? "Fan favorite": "Alright";</code></pre>
<h3>Another Example</h3>
<pre><code class="language-java">double shipping;
if (isPrimeMember) {
shipping = 0;
} else {
shipping = 3.99;
}</code></pre>
<p>Is equivalent to</p>
<pre><code class="language-java">double shipping = (isPrimeMember)? 0: 3.99;</code></pre>
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