lesson 2

• Data Type


  A classification system in Java used to specify the variables' value type
• The data type used varies on what kind of operation it needs to be used upon without any errors
• Primitive Data Types


  Data types that are built into a programming language, also called pre-defined data types
• Non-Primitive Data Types


  Data types that are not built into the programming language
• Primitive Data Types


  • Integers, floating points, characters are some examples
  • Can be used by the user to declare variables directly
• Integer


  Represents whole numbers, ranges from -2147483648 to 2147483647, uses 4 bytes of memory
• Integer


  • int Age = 21;
• Character


  Used for storing characters, uses 1 byte of memory, enclosed in single quotes
• Character


  • char MiddleInitial = 'A';
• Boolean


  True or False values, uses 1 byte, usually used for conditional operations and looping
• Boolean


  • bool is_true = true;
• Floating-Point


  Used for holding floating-point numbers (decimals and exponents), uses 4 bytes, stores 6-7 decimal points
• Floating-Point


  • float Pi = 3.14;
• Long


  Stores whole numbers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807
• Long


  • long num1 = 254512131215848;
• Short


  Stores whole numbers from -32,768 to 32,767
• Short


  • Short num2 = 30000;
• Double Float


  Same as float but has double precision on decimal values, stores 15 decimal digits
• Double Float


  • double Pi = 3.1415;
• Void


  Represents a valueless entity, used for functions that do not return a value
• Void


  • void FunctionName(){}
• Array


  A collection of items stored at continuous memory locations
• String


  Designed to hold a sequence of characters in a single variable
• Operators


  Symbols used to indicate an operation that tells what to do with the numbers in order to get to the final result
• Types of Operators


  • Arithmetic Operators
  • Relational/Comparison Operators
  • Logical Operators
• Arithmetic Operators


  • Addition (+), Subtraction (-), Multiplication (*), Division (/), Modulus (%), Increment (++), Decrement (--)
• Relational Operators


  • Equal to (==), Not Equal to (!=), Greater than (>), Less than (<), Greater than or Equal to (>=), Less than or Equal to (<=)
• Logical Operators


  • Logical and (&&), Logical or (||), Logical not (!)
• Implicit Conversion


  Java automatically converts between certain data types if they are compatible
• Implicit Conversion


  • int a = 10;

  long b = a; //this converts the value of a from int to long
• Casting


  You can use casting to convert between certain data types that are not automatically compatible
• Casting


  • double num = 1.2;

  int numm = (int) num; //convert the value of num from double to int
• String Parsing


  You can convert a String to another data type using parsing methods
• String Parsing


  • String thisString = "5";

  int thisInt = Integer.parseInt(thisString); //converting from string to int