Java Programming Week 1

What is .java file

Source Code

What is javac

Check & Compiles

What is .class file

compiled Java bytecode

JVM whats its role?

Executes bytecode

Different OS means?

Different JVM

What is the main method?

Place where Java program starts

EXTRA: Class-name must match filename!

What is the role of variables

Store and work with information

What are the 3 parts of a variable

type, name, value

What are the primitive data types

byte, short, int, long, double, float, boolean, char

Size of data types

byte → 1 byte

short → 2 bytes

int → 4 bytes

long → 8 bytes

float → 4 bytes

double → 8 bytes

char → 2 bytes

What condition to result decimal value?

At least one operand is a decimal value

Increase first then use value

y = ++x

use value first then increase

y = x++

What is the way to read user input?

the Scanner object

String format Specificers

%s - any type

%d - integer

%f - float, double

%e - float double

%nX - width n

%.nX - use n decimals

How does seeding work for random generator

Creates a random number generator with given

starting point (the seed). Sequence is the same if

the provided number is the same.

What is the use case alike of a switch?

It is alternative to repeated if-construction on value of var x