JAVA /
PRIMITIVE DATA TYPES

The Java is a statically typized language, so all variables must be declared before use.

Referenced types are e.g. String s = "Java"; where s is an object of String class.

Primitive types are e.g. int n = 2; where n will contain a value only.

Float:

• 1x float register on 32-bit systems, half float register on 64-bit systems,

• 1st bit: sign

• 2nd-9th bit: exponent

• 10th-32nd bit: fraction (mantisse)

• -> 7-8 decimal digits (e.g. from 0.12345*10^3 the 12345 part means 5 decimal digits) for safe use

Double:

• 2x float register on 32-bit systems, 1x float register on 64-bit system,

• 1st bit: sign

• 2nd-12th bit: exponent

• 13th-64th bit: fraction (mantisse)

• -> 15-16 digits for safe use

Char:

• char c = 'A' (value giving)

• char c = 65 (same result)

The default values are set by the constructor of the corresponding wrapper class.

The String is a wrapper class, declaring a String results "" as a default value set by its constructor.

Hexadecimal numbers are not primitive types but series of characters (for a byte, 2 characters) therefore can be stored in String wrapper object.

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