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<h1>Final Review December 6</h1>
<h2>Classes</h2>
<p>Here is how you can create a class called "Employee" with a non-default constructor (a constructor that takes parameters) and a getter and setter</p>
<pre><code class="language-java">public class Employee {
// Our private variables
private String name;
private double salary;
// Non-default constructor
public Employee(String name, double salary) {
this.name = name;
this.salarly = salary;
}
// This is a getter
public string getName() {
return name;
}
public double setSalarly(double salary) {
this.salary = salary;
}
}</code></pre>
<h2>For Loops + Arrays</h2>
<p>For loops are constructed in the following way</p>
<p><code>for (initialization; condition to stop; increment to get closer to condition to stop)</code></p>
<pre><code class="language-java">//Assume an array with variable name array is declared before
for (int i = 0; i < array.length; i++) {
// This code will loop through every entry in the array
}</code></pre>
<p>Note that you don't always have to start from zero, you can start anywhere from the array.</p>
<h2>For Loops + Arrays + Methods</h2>
<p>This is an example of how you can take in an array in a method</p>
<pre><code class="language-java">public static boolean isEven(int[] array) { // <-- Note the int[] array
for (int i = 0; i < array.length; i++) { // Iterate through the entire array
// If you find an odd number, return false
if (array[i] % 2 == 1) {
return false;
}
}
// If you didn't find any odd numbers, return true
return true;
}</code></pre>
<h2>File I/O</h2>
<p>Let's say that you have the following file</p>
<pre><code>4
chicken
3
salad</code></pre>
<p>And you want to make it so that you take the number, and print the word after it a certain number of times. For this example we would want to see the following</p>
<pre><code class="language-java">chicken chicken chicken chicken
salad salad salad</code></pre>
<p>Here is the code to write it</p>
<pre><code class="language-java">public static void printStrings() {
FileInputStream file = new FileInputStream("stuff.txt"); // File contents are in stuff.txt
Scanner scnr = new Scanner(file); // Scanner takes in a file to read
while (scnr.hasNext()) { // While there are still stuff in the file to read
int number = scnr.nextInt(); // Grab the number
String word = scnr.next(); // Grab the word after the number
// Print the word number times
for (int i = 0; i < number; i++) {
System.out.print(word);
}
// Put a new line here
System.out.println();
}
}</code></pre>
<h2>Recursion</h2>
<p>Look at handout and carefully trace recursion problems</p>
<h2>2D Arrays</h2>
<p>Declare a 2D int array with 4 rows and 7 columns</p>
<pre><code class="language-java">int[][] dataVals = new int[4][7];</code></pre>
<p>A 2D array with 4 rows and 7 columns has 7 * 4 = 28 entries.</p>
<p>If you want to sum up all the numbers in a 2 dimensional array, do the following</p>
<pre><code class="language-java">// Assume numbers is declared beforehand
int sum = 0;
for (int i = 0; i < numbers.length; i++) { // Loop through every row in the 2D array
for (int j = 0; j < numbers[i].length; j++) { // Loop through every column in a row
// This code now looks at one entry in a 2D array
sum += numbers[i][j];
}
}</code></pre>
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