Java Examination Tool Sebset (JETS)

The IB does not expect a specific standard of Java to be taught but a subset of Java called JETS for students to present OOP concepts

Conventions

Styles

Token	Conventions
Classes identifier	CapitalCamelCase
Variable identifier	camelCase
Method identifier	camelCase
Constant identifier	UPPER_CASE

Ordering

• Main class should be placed at the top
• Constructors should be place as the first method

Operators Permitted

• Arithmetic
  • -
  • -
  • -
  • /
  • %
• Relational
  • ==
  • !=
  • >
  • <
  • >=
  • <=
• Boolean
  • !
  • &&
  • ||

Types

Primitive Data Types

Primitive data types are data types other data types are constructed with, these are normally built-in as standard data types of programming languages, in JETS, these are:

type declaration	size	range	Standard	Default init value
byte	8 bits	$-128\le n \le 127$	unsigned	0
int	32 bits	$-2^{31}\le n \le 2^{32}$	signed	0
long	64 bits	$-2^{63}\le n \le 2^{63}$	signed	0
double	64 bits	$-4.9\times 10^{324} \le n \le 4.9\times 10^{324}$	IEEE 754-1984 (double precision binary floating-point)	0.0d
char	16 bits	$0 \le n \le 2^{16} -1$	UTF-16	'\u0000' 'a'
boolean	1 bit (logical) 1 byte (in-practice)	false

byte b = 120 // bytes is a 8 bit type with a range of -128<b<127, unsigned
int i = 1243 // int is a 32 bit type have a range of -2^31<i<2^31-1, signed
long
double
char
boolean

Scopes

Attribute Scopes

Java access modifiers used in JETS are:

class ClassIdentifier{
  public int n1 = 0; //Accessible by any class
  protected int n2 = 0; //Accessible by any extended class
  private int n3 = 0; //Only accessible by the class
}

Type Casting

Type casting refers to the converting of value to another type:

int n1 = (int)9.8 //9
double n2 = (double)6 //6.0f
byte n3 = (byte)1000 //Signed integer truncated to 8 bits: 1000%256-256 = -24
char n4 = (char)75 //K, from ascii mapping

Error Handling

Error handling refers to the handling of exceptions for functions that:

type funcIdentifier () throws IOException

try{ /*commands*/ }
  catch(Exception e){ /*Error condition handle*/ }