17) Classification of data types in the programming language Java.

Data type defines a set of permitted values on which the legal operations can be performed.  In java, all the variables needs to be declared first i.e. before using a particular variable, it must be declared in the program for the memory allocation process. Like int pedal = 1;

This statement exists a field named "pedal" that holds the numerical value as 1. The value assigned to a variable determines its data type, on which the legal operations of java are performed. This behavior specifies that, Java is a strongly-typed programming language.  The data types in the Java programming language are divided into two categories  and can be explained using the following hierarchy structure :

•  Primitive Data Types 

•  Reference Data Types

 Primitive Data Types   The primitive data types are predefined data types, which always hold the value of the same data type, and  the values of a primitive data type don't share the state with other primitive values. These data types are named by a reserved keyword in Java  programming language. 

There are eight primitive data types supported by Java programming language : byte  The byte data type is an 8-bit signed two's complement integer. It ranges from -128 to127 (inclusive). This type of data type is useful to save   memory  in large arrays.. We can also use byte instead of int  to increase the limit of the code. The syntax of declaring a byte type variable is shown as: byte b = 5;

 int   The int data type is used to store the integer values not the fraction values. It is a 32-bit signed two's complement integer data type. It ranges from -2,147,483,648 to 2,147,483,647 that is more enough to store large number in your program.  However for wider range of values use long. The syntax of declaring a int type variable is shown as:

int num = 50;

 float  The float data type is a single-precision 32-bit IEEE 754 floating point. It ranges from 1.40129846432481707e-45 to 3.40282346638528860e+38 (positive or negative). Use a float (instead of double) to save memory in large arrays. We do not use this data type for the exact values such as currency. For that we have to use java.math.BigDecimal class. The syntax of declaring a float type variable is:

float f = 105.65;     float f = -5000.12;

 double   This data type is a double-precision 64-bit IEEE 754 floating point. It ranges from 4.94065645841246544e-324d to 1.79769313486231570e+308d (positive or negative). This data type is generally the default choice for decimal values. The syntax of declaring a double type variable is shown as:

double d =6677.60;

 char  The char data type is a single 16-bit, unsigned Unicode character. It ranges from 0 to 65,535. They are not integral data type like int, short etc. i.e. the char data type can't hold the numeric values. The syntax of declaring a char type variable is shown as:

 char caps = 'c'; 

 boolean  The  boolean data type represents only two values: true and false and occupy is 1-bit in the memory. These values are keywords in Java and  represents the two boolean states: on or off, yes or no. We use boolean data type for specifying conditional statements as if, while, do, for. In Java, trueand false are not the same as True and False. They are defined constants of the language. The syntax of declaring a boolean type variable is shown as:

boolean result = true;

Floating-point numbers

A floating-point number represents a real number that may have a fractional values i.e. In the floating type of variable, you can assign the numbers in an in a decimal or scientific notation. Floating-point number have only a limited number of digits, where most values can be represented only approximately. The floating-point types are float and double with a single-precision 32-bit IEEE 754 floating point and double-precision 64-bit IEEE 754 floating point respectively.