Chapter 2: Language Fundamentals

Chapter 2: Language Fundamentals

1. Primitives

   • Non-object data type that represent numbers and simple values (8 total)
     • 6 Primitives Represent Numbers and each has a different size
       • to save space you want to use the primitive with the smallest data size
     • char
       • contains a single Unicode character like 'a', '9', and '&' that allows chars to contain characters that do not exist in the English alphabet
     • boolean
       • Can only contain 2 states: true/false

2. Variables

   • Data placeholders
     • 1) Must have a declared type
       • 2) Has a name or an identifier
         • Constants
           • variables that once assigned cannot be changed
             • declare a constant using the word final and the constant names are all in upper case with words separated by underscores
               • final int ROW_Count = 50;
         • unlimited-length sequence of Java letters and digits
           • Java Letters
             • ASCII Latin letters A-Z, a-z, underscore, and dollar sign
               • *dollar sign only should be used in mechanically generated source code or to access preexisting names on legacy systems
           • JAVA Digits
             • ASCII 0-9
         • must begin with a Java letter
           • Case sensitive
         • must not be a JAVA keyword , a boolean literal or the null literal
         • Must be unique within its scope
       • reference type
         • a reference of an object
       • primitive type
         • holds a primitive
   • Declare a variable by writing type first followed by name with semicolon.
     • can declare multiple of the same type using a comma
       • Can assign a value at the same time as declaring

3. Literals

   • source code representation of a value
     • Literals of primitive types
       • Integre literals
         • Floating Literals
           • Boolean Literals
             • Character Literals
               • Unicode Character or escape sequence enclosed in a single quote
                 • escape sequence is representation of a Unicode character that cannot be inputed by a keyboard
                   • Examples:
                     • 'a' , 'Z' , '0'
                   • Escape sequence examples:
                     • '\b'
             • only two variables: True and False
           • has a whole number part, a decimal point, a fractional part, and an optional exponent
             • float
               • 32 bits in size
             • double
               • 64 bits in size
         • used to assign values to variable s of type byte, short, int, and long
           • Cannot assign a value that exceeds value of capacity of a variable
             • highest for a byte is 127
             • assign value to a long by suffixing the number with L/l

4. Encoding Sets

   • Separators
     • Special Characters
   • JAVA supports Unicode character encoding set and program element names are not restricted to ASCII characters
     • Each character in the ASCII is represented by 7 bits. There are 128 characters in this set
       • lowercase & uppercase latin letters, number and punctuation marks
         • 128 more added in extended ASCII
     • Unicode is a character set that includes all characters in all languages. Different levels of bit storage per character are seen in these encodings
       • UTF - 8
         • UTF-16
           • UTF-32

Images and files in the map