<!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 in CPSC 220 Sept 25 2017</h1>
<h2>Constants</h2>
<p>Adding the keyword <code>final</code> in front of a variable declaration makes the variable constant. Meaning you cannot later change it in the code.</p>
<pre><code class="language-java">final int MAX = 10;</code></pre>
<p>By industry norm, the style of the variable is to have it in all caps.</p>
<p>You CANNOT do the following</p>
<pre><code class="language-java">final int MAX = 10;
MAX = 15;</code></pre>
<h2>Using Libraries</h2>
<ol>
<li>Import the library</li>
<li>Find the method that is appropriate</li>
<li>Use it</li>
</ol>
<p>Example:</p>
<pre><code class="language-java">import java.util.Math;
public class MathTest {
public static void main(String[] args) {
double answer = Math.ceil(5.4);
System.out.println(Math.ceil(4.5));
}
}</code></pre>
<h2>Typecasting / Type Conversions</h2>
<p>You can only cast a variable if you are casting it to a type that is larger than the one it was previously. The expression Polack used is that you cannot fit into super skinny jeans, but you can fit into bigger pants.</p>
<pre><code class="language-java">double dnum;
float fnum;
int inum;
dnum = (double)fnum * (double)inum;</code></pre>
<h2>Char vs String</h2>
<p><code>String</code>s are initialized in Java with double quotes while <code>char</code>s are initialized with single quotes</p>
<pre><code class="language-java">char initial = 'j';
String name = "Jennifer";</code></pre>
<p>Characters can be read in as an integer.</p>
<h2>Random Numbers</h2>
<ol>
<li>Import <code>java.util.Random;</code></li>
<li>Declare the random number generator</li>
<li>Initialize with <code>new</code></li>
<li>Use it</li>
</ol>
<pre><code class="language-java">import java.util.Random;
public class RandTest {
public static void main(String[] args) {
Random rand;
rand = new Random();
int number = rand.nextInt(100); // Random generates number between 0-99
}
}</code></pre>
<p>How do you generate numbers in a different range? [50, 150]</p>
<pre><code class="language-java">rand.nextInt(100); // 0-99
rand.nextInt(101) // 0 - 100
rand.nextInt(101) + 50 //50-150</code></pre>
<p>In more general terms</p>
<pre><code class="language-java">rand.nextInt(end - start + 1) + start</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>