<!DOCTYPE html> <html> <head> <meta charset="utf-8" /> <meta name="author" content="Brandon Rozek"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <meta name="robots" content="noindex" /> <title>Brandon Rozek</title> <link rel="stylesheet" href="themes/bitsandpieces/styles/main.css" type="text/css" /> <link rel="stylesheet" href="themes/bitsandpieces/styles/highlightjs-github.css" type="text/css" /> </head> <body> <aside class="main-nav"> <nav> <ul> <li class="menuitem "> <a href="index.html%3Findex.html" data-shortcut=""> Home </a> </li> <li class="menuitem "> <a href="index.html%3Fcourses.html" data-shortcut=""> Courses </a> </li> <li class="menuitem "> <a href="index.html%3Flabaide.html" data-shortcut=""> Lab Aide </a> </li> <li class="menuitem "> <a href="index.html%3Fpresentations.html" data-shortcut=""> Presentations </a> </li> <li class="menuitem "> <a href="index.html%3Fresearch.html" data-shortcut=""> Research </a> </li> <li class="menuitem "> <a href="index.html%3Ftranscript.html" data-shortcut=""> Transcript </a> </li> </ul> </nav> </aside> <main class="main-content"> <article class="article"> <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 "when our variable in consideration is equal to..."</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 > 4) { output = "Fan favorite"; } else { output = "Alright"; }</code></pre> <p>Is equivalent to</p> <pre><code class="language-java">String output = ""; output = (movieRating > 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> </article> </main> <script src="themes/bitsandpieces/scripts/highlight.js"></script> <script src="themes/bitsandpieces/scripts/mousetrap.min.js"></script> <script type="text/x-mathjax-config"> MathJax.Hub.Config({ tex2jax: { inlineMath: [ ['$','$'], ["\\(","\\)"] ], processEscapes: true } }); </script> <script type="text/javascript" src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML"> </script> <script> hljs.initHighlightingOnLoad(); document.querySelectorAll('.menuitem a').forEach(function(el) { if (el.getAttribute('data-shortcut').length > 0) { Mousetrap.bind(el.getAttribute('data-shortcut'), function() { location.assign(el.getAttribute('href')); }); } }); </script> </body> </html>