Language Fundamentals

Language Fundamentals

1. Encoding Sets

   • --(American Standard Code for Information Interchange) --> represent 128 alphanumeric characters, includes the lower case and upper case Latin letters, numbers, and punctuation marks -- extended ASCII --> includes another 128 characters
   • ISO((International Standards Organization)-8859-1/ Latin-1 = Each character in ISO-8859-1 is represented by 8 bits as well.
   • Unicode = attempts to include all characters in all languages in the world into one single character set
     • a Unicode character was represented by 16 bits, which were enough to represent more than 65,000 different characters
       • Unicode text is not as efficient as storing and transmitting ASCII or Latin-1 characters
     • character encoding can make it more efficient to store and transmit Unicode text
       • character encoding = data compression
         • UTF-8, UTF-16, UTF-32

2. Primitives = data types

   • There are eight primitive types in Java, each with a specific format and size
     • --byte, short, int, and long can only hold integers or whole numbers float or a double. float or a double. --float or double are for numbers with decimals
     • --char type can contain a single Unicode character, such as ‘a’, ‘9’, and ‘&’. Unicode allows chars to also contain characters that do not exist in the English alphabet. -- boolean can contain one of two possible states (false or true).
     • Note: Use long only when needed because it consumes more memory

3. Variables = data placeholders

   • Java is a strongly typed language, therefore every variable must have a declared type. There are two data types in Java
     • 1.reference types. A variable of reference type provides a reference to an object.
     • 2.primitive types. A variable of primitive type holds a primitive.
     • a Java variable also has a name or an identifier and rules for choosing
       • 1. unlimited-length sequence of Java letters and Java digits. must begin with a Java letter. 2. not be a Java keyword, a boolean literal, or the null literal. 3. unique within its scope. ”
   • declare a variable = by writing the type first, followed by the name + a semicolon

4. Constants = variables whose values, once assigned, cannot be changed

   • declare a constant = by using the keyword final
     • constant names are all in upper case with words separated by underscores.

5. Literals

   • Use: When you need to assign values to variables in your program, such as number 2 to an int. You'll need to write the value representation in a format that the Java compiler understands. This source code representation of a value is called literal
   • three types of literals: literals of primitive types, string literals, and the null literal
     • Focus --> primitive types = have four subtypes: integer literals, floating-point literals, character literals, and boolean literals.
       • Integer
         • may be written in decimal (base 10), hexadecimal (base 16), or octal (base 8).
           • used to assign values to variables of types byte, short, int, and long. Note --> however, you must not assign a value that exceeds the capacity of a variable
             • To assign a value to a long, suffix the number with the letter L or l
       • Floating-point
         • 4 parts: --a whole number part --a decimal point --a fractional part -- an optional exponent
         • 2 types: -- float: 32 bits in size. -- double. 64 bits in size.
           • For both: whole number part of 0 is optional
       • Character
         • Unicode character or an escape sequence enclosed in single quotes
           • escape sequence is the representation of a Unicode character that cannot be entered using the keyboard or that has a special function in Java
       • Boolean
         • boolean type has two values, represented by literals true and false

6. Separators

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