Primitive Data Types

The Java programming language is statically-typed, which means that all variables must first be declared before they can be used. This involves stating the variable's type and name

 int gear = 1;

Doing so tells your program that a field named "gear" exists, holds numerical data, and has an initial value of "1". A variable's data type determines the values it may contain, plus the operations that may be performed on it. In addition to int, the Java programming language supports seven other primitive data types. A primitive type is predefined by the language and is named by a reserved keyword. Primitive values do not share state with other primitive values. The eight primitive data types supported by the Java programming language are: 

• byte: The byte data type is an 8-bit signed two's complement integer. It has a minimum value of -128 and a maximum value of 127 (inclusive). The byte data type can be useful for saving memory in large arrays, where the memory savings actually matters. They can also be used in place of int where their limits help to clarify your code; the fact that a variable's range is limited can serve as a form of documentation. 

• short: The short data type is a 16-bit signed two's complement integer. It has a minimum value of -32,768 and a maximum value of 32,767 (inclusive) .
  you can use a short to save memory in large arrays, in situations where the memory savings actually matters. 

   int: By default, the int data type is a 32-bit signed two's complement integer, which has a minimum value of -2³¹ and a maximum value of 2³¹.int data type to represent an unsigned 32-bit integer, which has a minimum value of 0 and a maximum value of 2³²-1. Use the Integer class to use int data type as an unsigned integer. 

  long: The long data type is a 64-bit two's complement integer. The signed long has a minimum value of -2⁶³ and a maximum value of 2⁶³-1.long data type to represent an unsigned 64-bit long, which has a minimum value of 0 and a maximum value of 2⁶⁴-1.

  float: The float data type is a single-precision 32-bit .

  double: The double data type is a double-precision 64-bit .

  boolean: The boolean data type has only two possible values: true and false.

  char: The char data type is a single 16-bit Unicode character.  

  In addition to the eight primitive data types listed above, the Java programming language also provides special support for character strings via the java.lang.String class. Enclosing your character string within double quotes will automatically create a new String object; for example, String s = "this is a string";. String objects are immutable, which means that once created, their values cannot be changed. The String class is not technically a primitive data type, but considering the special support given to it by the language, you'll probably tend to think of it as such. 

  Default Values:

  It's not always necessary to assign a value when a field is declared. Fields that are declared but not initialized will be set to a reasonable default by the compiler. this default will be zero or null, depending on the data type.

  The following chart summarizes the default values for the above data types:

  Data Type	Default Value (for fields)
  byte	0
  short	0
  int	0
  long	0L
  float	0.0f
  double	0.0d
  char	'\u0000'
  String (or any object)	null
  boolean	false

  Local variables are slightly different; the compiler never assigns a default value to an uninitialized local variable. If you cannot initialize your local variable where it is declared, make sure to assign it a value before you attempt to use it. Accessing an uninitialized local variable will result in a compile-time error. 

  Difference between datatypes and literals:

  Data types :

  Primitive types are special data types built into the language; they are not objects created from a class 

  Literal : 

  A Literal is the source code representation of a fixed value; literals are represented directly in your code without requiring computation 

  Example: 

  boolean result = true;
  
  boolean - is data type
  true - is literal

  Next we are going to discuss about Literal .