website/static/~brozek/index.html?labaide%2Fspring2018%2Fcpsc220%2Ffeb8.html

150 lines
4.9 KiB
HTML
Raw Normal View History

2020-01-16 04:07:02 +00:00
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta name="author" content="Fredrik Danielsson, http://lostkeys.se">
<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 &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>
</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>