mirror of
https://github.com/Brandon-Rozek/website.git
synced 2025-11-03 23:01:13 +00:00
161 lines
5.6 KiB
HTML
161 lines
5.6 KiB
HTML
<!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 January 25</h1>
|
|
<h2>Strings</h2>
|
|
<p>These are concatenated chars</p>
|
|
<pre><code class="language-java">'d' + 'o' + 'g' // equivalent to "dog"</code></pre>
|
|
<pre><code class="language-java">"straw" + "berry" // strawberry</code></pre>
|
|
<p>Strings are denoted by double quotes <code>""</code> rather than a string which is denoted by single quotes <code>''</code></p>
|
|
<p>String is not a primitive type, it is a class. Hence, why it is capitalized in Java.</p>
|
|
<p>The <code>java.lang.String</code> is automatically imported in Java.</p>
|
|
<p>To declare and initialize a String</p>
|
|
<pre><code class="language-java">String name = "Henry";</code></pre>
|
|
<p>In memory it appears as</p>
|
|
<table>
|
|
<thead>
|
|
<tr>
|
|
<th>H</th>
|
|
<th>'e'</th>
|
|
<th>'n'</th>
|
|
<th>'r'</th>
|
|
<th>'y'</th>
|
|
</tr>
|
|
</thead>
|
|
<tbody>
|
|
<tr>
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<h3>String Methods</h3>
|
|
<pre><code class="language-java">int length()</code></pre>
|
|
<pre><code class="language-java">boolean equals(String another)</code></pre>
|
|
<pre><code class="language-java">boolean startsWith(String prefix)</code></pre>
|
|
<pre><code class="language-java">boolean endsWith(String suffix)</code></pre>
|
|
<pre><code class="language-java">String substring(int start, int end)</code></pre>
|
|
<pre><code class="language-java">int indexOf(int ch)</code></pre>
|
|
<pre><code class="language-java">String toLowerCase()</code></pre>
|
|
<h3>Using String Methods</h3>
|
|
<pre><code class="language-java">char first = name.charAt(0);</code></pre>
|
|
<p>Remember in Java, that it starts counting from zero! If you try to access a letter that doesn't exist, it will produce an <code>IndexOutOfBounds</code> error.</p>
|
|
<h2>Errors</h2>
|
|
<p>There are two types of errors, compile-type errors and run-time errors. Later we will talk about debugging skills such as making "breakpoints" in your code so you can analyze the different variable values.</p>
|
|
<h3>Compile Time Errors</h3>
|
|
<p>Compile time errors are generated due to syntax errors. Forgot a semicolon? Missing a brace? </p>
|
|
<h3>Run-time Errors</h3>
|
|
<p>These are logic errors. Not derived from syntax errors. An example of one that was discussed earlier is the <code>IndexOutOfBounds</code> error.</p>
|
|
<h2>Tricky Thing About Input</h2>
|
|
<p>Let's talk about input right now. Let's say you have the following scenario</p>
|
|
<pre><code class="language-java">Scanner input = new Scanner(System.in);
|
|
System.out.println("Enter pet's age: ");
|
|
int age = input.nextInt();
|
|
System.out.println("Enter pet's name: ");
|
|
String name = input.nextLine();
|
|
System.out.println("Enter pet's breed: ");
|
|
String breed = input.next();</code></pre>
|
|
<p>Then when we start to run the program...</p>
|
|
<pre><code class="language-reStructuredText">Enter pet's age:
|
|
14
|
|
Enter pet's name:
|
|
Enter pet's breed:
|
|
Labradoodle</code></pre>
|
|
<p>Why did it skip pet's name? Let's run through the process again</p>
|
|
<pre><code class="language-reStructuredText">Enter pet's age:
|
|
14 [ENTER]
|
|
Enter pet's name:
|
|
Enter pet's breed:
|
|
Labradoodle</code></pre>
|
|
<p>Here the [ENTER] key gets saved into name.</p>
|
|
<p>To resolve this, just use an <code>input.nextLine()</code> to throw away that [ENTER]</p>
|
|
<pre><code class="language-java">Scanner input = new Scanner(System.in);
|
|
System.out.println("Enter pet's age: ");
|
|
int age = input.nextInt();
|
|
System.out.println("Enter pet's name: ");
|
|
input.nextLine();
|
|
String name = input.nextLine();
|
|
System.out.println("Enter pet's breed: ");
|
|
String breed = input.next();</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>
|