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<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>
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