Lecture for February 27th

Review for midterm

Chapter 1 – Code Style, API

Chapter 2 – Variables & Assignments, strings

Chapter 3 – input & output

Chapter 4 – branches (if, if/else, switch)

Chapter 5 – loops (while, for), scope

Chapter 6 – File Reading and Writing

Separated vs Connected Branches

What is the output of this code?

String preferredLanguage = "Spanish";
if (preferredLanguage.equals("Chinese")) {
    System.out.println("Ni hao!");
}
if (preferredLanguage.equals("Spanish")) {
    System.out.println("Hola!");
}
if (preferredLanguage.equals("French")) {
    System.out.println("Bonjour!");
}
if (preferredLanguage.equals("German")) {
    System.out.println("Gutentag!")
} else {
    System.out.println("Hello!")
}

The output is

Hola!
Hello!

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.

Since the preferred language equals Spanish it outputs Hola! But since the language is also not German it prints out Hello! as well.

Using an Array

Square brackets notation is used to access elements, array slots can be used as variables

int[] array = new int[7]; // Creates an integer array of size 7
array[0] = 5;

Swapping Elements

You can swap x and y in the following way with a temporary variable

int x = 6;
int y = 1;

int temp = x;

x = y;
y = temp;

Two-Dimensional Arrays

// Creates a 2D array of two rows and three columns
int[][] a = new int[2][3]

You can access an element of this 2D array using the conventional square bracket notation

a[0][0] = 5;