Introduction to

Java

http://www.slideshare.net/annagerber/intro-to-java

instructions

Programming languages

.java file

.class file

compile

Integrated Development Environment (IDE)

Objects & ClassesObjects have:

State (fields)

Behaviour (methods)

Classes provide “blueprints” for different kinds of objects

public class MyClass {

}

main methodpublic class MyClass {

public static void main(String[] args){

// This is a comment

}

}

StatementsString name = “Anna”;

int numberOfThings = 0;

MyClass m = new MyClass();

m.doSomething();

// This is a comment on a single line

/* This is a longer comment * that can go over more than one line */

Input and Output (IO)

Exercise 1Write a program to output “Hello, World!”

Exercise 2Write a program that asks someone to enter their name and then prints “Hello, <name>”

Conditional behaviourBoolean logic:

and &&

or ||

not !

equals ==

not equal !=

greater than >

less than <

if (anna.isTired) { if (isNightTime && !anna.isWorking) { anna.sleep(); } else { anna.drinkCoffee(); }}

Comparing Strings== and != are for basic types like integers

For objects use equals() e.g. to compare Strings:

If (string1.equals(string2)) …

If (string1.equalsIgnoreCase(string2)) …

Loopswhile (coffee) {

person.drink(coffee);

}

for (int i = 0; i < 10; i++) {

// do something 10 times

}

Exercise 3Write a program with the following behaviour:

Ask the person to enter some text If the person says “yay” the program responds with “hey” If the person says “boo” the program responds with “hoo” If the person says “how” the program responds with “now”

Challenge: Keep prompting and responding until the input is “bye”

Putting it all together: Choose your own adventureWrite a choose your own adventure game!

System.out.println(“You are being chased by a T-Rex, do you a) run or b) fight?”);input = scan.next();if ( input.equals(“a”)) ...