Chapter 2: Language Fundamentals

Chapter 2: Language Fundamentals

1. ASCII and Unicode

   • ASCII - American Standard Code for Information Interchange. Character set used by computers to represent alphanumeric characters. 128 characters, upper and lowercase Latin letters, and punctuation marks. Extended ASCII includes various additional 128 characters.
   • Latin-1 is another character set, contains characters required for writing in most western European languages. However, does not account for Asian languages such as Chinese or Korean.
   • Unicode was developed to provide a universal character set for all languages to be able to exchange information using computers, and is used in many languages and adopted by numerous industry leaders, i.e. Google, IBM, Apple. However, Unicode requires 4x more data to be transferred compared to ASCII and Latin-1.
     • To solve the data issue, Unicode endorses three types of character encodings, which is much like data compression, and allows data to be transferred more easily. These are UTF-8, UTF-16, and UTF-32.

2. Separators

   • Important symbols that perform specific functions. Include parentheses(()), braces({}), brackets([]), angle brackets (<>), semicolon(;), colon(:), comma(,), period(.).

3. Primitives - data types in Java that are not objects.

   • Byte, short, int, long, float, double are the first six primitives and they represent numbers. Each have a different size.
   • Char and boolean are the remaining primitive data types. Char can be any Unicode character. Boolean contains the states 'true' or 'false'

4. Variables- data placeholders

   • There are two variable types in Java, reference type and primitive type. Variable type references an object while primitive type holds a primitive. A Java variable must also have a name or identifier.

5. Constants - variables whose value cannot be changed once assigned. Declare a constant using keyword "final". By convention constant names are in uppercase with words separated by underscores.

6. Literals - when you assign a value to a variable and write source code in a way Java understands. This is a Literal, there are three kinds of Literals, string literals, literals of primitive types, and null literals. Only discuss literals of primitive types in this chapter.

   • Integer Literals - used to assign values to variables type byte, short, int and long. Cannot assign value that exceeds capacity of the variable.
   • Floating point literals - floating point numbers have a whole number part, decimal point, fractional part, and optional exponent. Two types of floating points in Java, float (32 bit size) and double (64 bit size).
   • Boolean Literals - hold either the true or false value.
   • Character literals - a Unicode character or escape sequence enclosed in single quotes. An escape sequence is a representation of a Unicode character that cannot be entered with the keyboard or has a special function within Java.