Chapter 1b

1
Chapter 1b

• Using Data

2
Primitive Data Types

• Type Bytes Constant
• boolean 1 bit true / false
• byte 1 127
• char 2 a
• double 8 3.14159
• float 4 3.14159F
• int 4 10
• long 8 9223372036L
• short 2 32767

3
Integer Types

• Integer characteristics
• byte, short, int long are all integers
• Ranges
• byte -128 to 127
• short -32,768 to 32,767
• int -2,147,483,648 to 2,147,483,647
• long -9,223,372,036,854,775,808 to
• 9,223,372,036,854,775,807

4
Floating Point Types

• Floating point characteristics
• float (6-7 significant digits)
• range -/1.4023984610-45
• to
• -/3.402823471038
• double (15 significant digits)
• range -/1.7976931348623157010308 to
• -/4.9406564584124654410-324

5
Variable Definitions

• boolean condition true
• byte age 23
• char character a
• double target 123.23
• float volume 3.12F
• int counter 0
• long lightSpeed 186000L
• short ton 2000

6
Variable Naming Rules Conventions

• Rules
• Variable names follow the same rules as those for
  classes
• Conventions
• Variable names begin with lowercase letters
• Each following word is uppercase
• float volume
• float totalVolume

7
Arithmetic Operators

• Priority Type Operator Example
• 1 Unary - -A
• A
• cast (type) (float)
• 2 Multiplicative AB
• / A/B
• AB
• 4 Additive AB
• - A-B
• 13 Assignment AB

8
Relational Logical Operators

• Operator Description Example
• lt Less than A lt B
• gt Greater than A gt B
• Equal to A B
• lt Less than or equal to A lt B
• gt Greater than or equal to A gt B
• ! Not equal to A ! B
• Or A B
• And A B
• ! Not !A

9
Boolean Operators

• Operator Description Example
• And operator x y
• Or operator x y
• Exclusive or x y
• ltlt Shift left x ltlt 1
• gtgt Signed shift right x gtgt 1
• gtgtgt Unsigned shift right x gtgtgt 1

10
Type Conversion

• Type conversion happen in two ways
• Implicit
• Explicit
• Implicit
• Promotion process float int
• Explicit
• type cast (float) x
• Going from a higher to a lower data type requires
  a type cast

11
Promotion Order

• Promotion order (highest to lowest)
• 1. double
• 2. float
• 3. long
• 4. int
• 5. short
• 6. byte

12
Unicodes

• Java characters are represented using Unicode
• 16 bit coding scheme
• represented using hexadecimal value
• char letter \u0041 // A decimal 65
• Unicode info
• www.unicode.org

13
Character Escape Sequences

• Sequences
• \b backspace \u0008
• \t tab \u0009
• \n newline \u000a
• \f form feed \u000c
• \r carriage return \u000d
• \ quotation mark \u0022
• \ single quotation mark \u0027
• \\ backslash \u005c

14
Variable Initialization

• Local variables (variables defined inside
  methods) must be initialized by the programmer
  before using them
• Instance and class variables are automatically
  initialized by the compiler when declared by the
  programmer

15
FYI

• All Java floating point data types follow the
  IEEE 754 specification

16
FYI

• Precedence Chart
• ( ) Parenthesis
• ( ) Function call
• Array subscript
• . Object member access
• Prefix increment
• -- Prefix decrement
• Unary plus
• - Unary minus
• ! Unary logical negation
• ( type ) Unary casting
• new Creating Object
• Multiplication
• / Division
• Integer modulus
• Addition
• - Subtraction

17
FYI

• Precedence Chart - cont.
• lt Less then
• lt Less than or equal to
• gt Greater than
• gt Greater than or equal to
• instanceof Checking object type
• Equal comparison
• ! Not equal
• Logical AND
• Logical OR
• ? Ternary condition
• Assignment
• Addition assignment
• - Subtraction assignment
• Multiplication assignment
• / Division assignment
• Integer modulus assignment
• Postfix increment
• -- Postfix decrement