Variables

• byte (number, 1 byte)
• short (number, 2 bytes)
• int (number, 4 bytes)
• long (number, 8 bytes)
• float (float number, 4 bytes)
• double (float number, 8 bytes)
• char (a character, 2 bytes)
• boolean (true or false, 1 byte)

Variables

Conditionals

if (/*check a condition*/) {
     //dosomething
} else if (/*condition*/) {
     //dosomethingelse
} else {
     //dosomethingelse
}

Conditionals

int a = 4;

int b = 5;

result = a < b // true
result = a > b // false
result = a <= 4 // a smaller or equal to 4 - true
result = b >= 6 // b bigger or equal to 6 - false
result = a == b // a equal to b - false
result = a != b // a is not equal to b - true
result = a > b || a < b // Logical or - true
result = 3 < a && a < 6 // Logical and - true
result = !result // Logical not - false

Loops

For Loops

for (int i = 0; i < 3; i++) {
    //do something
}

while (/*condition*/) {
    //do something
}

do {
    //do something
} while(/*condition*/);

While Loops

Loops

Break

int i;
for (i = 0; i < 5; i++) {
    if (i >= 2) {
        break;
    }
    System.out.println("Yuhu");
}
System.out.println(i);
// Output:
// Yuhu
// Yuhu
// 2

Loops

Break and Continue

int i;
for (i = 0; i < 5; i++) {
    if (i >= 3) {
        break;
    }
    System.out.println("Yuhu");
    if (i >= 1) {
        continue;
    }
    System.out.println("Tata");
}
System.out.println(i);
// Output: Yuhu, Tata, Yuhu, Yuhu, 3

Fizzbuzz

The "Fizz-Buzz test" is an interview question designed to help filter out the 99.5% of programming job candidates who can't seem to program their way out of a wet paper bag.

Challenge

Write a program that prints the numbers from 1 to 100. But for multiples of three print “Fizz” instead of the number and for the multiples of five print “Buzz”. For numbers which are multiples of both three and five print “FizzBuzz”.

Fizzbuzz

Solution

public class FizzBuzz {
    public static void main(String[] args) {
        for (int i = 1; i <= 100; i++) {
            if (i % 15 == 0) {
                System.out.println("FizzBuzz")
            } else if (i % 3 == 0) {
                System.out.println("Fizz");
            } else if (i % 5 == 0) {
                System.out.println("Buzz");
            } else {
                System.out.println(String.valueOf(i));
            }
        }
    }
}

Object-oriented programminG

Also known as OOP, hence the previous slide's pun.

• In OOP, a program consists of interacting objects
• To write a program like this, you have to define what objects know, how they're created, and how they interact with other objects

OBJECTS

ACCEPT the pun.

• Objects are described in terms of attributes and behaviors
• Attributes describe objects, and behaviors are what objects can do

CLASSES

Accept it.

• In order to use an object, you must define it in a class.
• A class can be thought of as a mold/blueprint that a computer uses to create objects. 
• Ex: When building a house, a construction crew uses a certain blueprint to make the house. However, clients might want their houses to be different. These different houses represent objects of the original blueprint. 

methods

• To instruct an object to execute a task, a message is sent to the object. 
• This message is known as a method.

EXAMPLE CLASS

public class Main
{
    private final int a = 10;
    private final int b = 42;

    public int add(int anInt, int anotherInt)
    {
        return anInt + anotherInt;
    }

    public int multiply(int anInt, int anotherInt)
    {
        return anInt * anotherInt;
    }

    public static void main(String[] args)
    {

        System.out.println(add(a, b)); // should return 52
        System.out.println(multiply(a, b)); // should return 420
    }
}