by Dinesh Thakur

Identifier is is a simple variable name which is defined as the value container. The type of value stored by identifier is defined by the special java keyword is termed as primitive data type.

In the given example there are some identifiers have been used like byteident, shortident, intident, longident, charident, stringident, floatident, doubleident. And there are some primitive data types of used identifiers have been also used in the program like byte, short, int, long, float, double, char and String. 

In addition to the rules that governs identifiers, Java programmers follow certain style conventions to make up names for classes, methods, constants, variables, interfaces and packages.

1. Class names in Java begins with a capital letter. Class names should be descriptive names or noun phrases but not very long. If class name contains multiple words then each subsequent word in the class name begins with a capital letter. For example: Employee, GradeBook, CommissionEmployee, ProcessExamResult etc.

2. Names of the fields that are not final and method's name should begin with a lowercase letter. Method names should be verbs or verb phrases. However, if they contain multiple words then each subsequent word in the name begins with a capital letter. For example: firstName, salary, getName, getMaximum etc.

3. Names of the packages intended only for local use should have a first identifier that begins with a lowercase letters.

4. Constant represent fixed values that cannot be altered. For example, PI is constant with a fixed value 3.14159. Such constants should be written in uppercase.

These conventions are followed so that programmers can distinguish whether an identifier corresponds to a class name, variable, method, package in a program.

All the data type has it's own capacity to keep the maximum value. Which have been mentioned below : 

Primitive Data Types

byte Byte-length integer 8-bit two's complement
short Short integer 16-bit two's complement
int Integer 32-bit two's complement
long Long integer 64-bit two's complement
Real numbers
float Single-precision floating point 32-bit IEEE 754
double Double-precision floating point 64-bit IEEE 754
Other types
char A single character 16-bit Unicode character
boolean A boolean value (true or false) true or false