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91 lines
1.7 KiB
Markdown
91 lines
1.7 KiB
Markdown
# Lecture for February 27th
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## Review for midterm
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Chapter 1 -- Code Style, API
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Chapter 2 -- Variables & Assignments, strings
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Chapter 3 -- input & output
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Chapter 4 -- branches (if, if/else, switch)
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Chapter 5 -- loops (while, for), scope
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Chapter 6 -- File Reading and Writing
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## Separated vs Connected Branches
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What is the output of this code?
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```java
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String preferredLanguage = "Spanish";
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if (preferredLanguage.equals("Chinese")) {
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System.out.println("Ni hao!");
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}
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if (preferredLanguage.equals("Spanish")) {
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System.out.println("Hola!");
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}
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if (preferredLanguage.equals("French")) {
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System.out.println("Bonjour!");
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}
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if (preferredLanguage.equals("German")) {
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System.out.println("Gutentag!")
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} else {
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System.out.println("Hello!")
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}
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```
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The output is
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```reStructuredText
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Hola!
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Hello!
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```
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This is because each of the if statements are independent from each other. Whether or not the if statement gets check is not affected by the if statements around it.
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Since the preferred language equals Spanish it outputs `Hola!` But since the language is also *not German* it prints out `Hello!` as well.
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## Using an Array
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Square brackets notation is used to access elements, array slots can be used as variables
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```java
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int[] array = new int[7]; // Creates an integer array of size 7
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array[0] = 5;
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```
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## Swapping Elements
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You can swap `x` and `y` in the following way with a *temporary* variable
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```java
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int x = 6;
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int y = 1;
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int temp = x;
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x = y;
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y = temp;
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```
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## Two-Dimensional Arrays
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```java
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// Creates a 2D array of two rows and three columns
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int[][] a = new int[2][3]
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```
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You can access an element of this 2D array using the conventional square bracket notation
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```java
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a[0][0] = 5;
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```
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