Class_Till_Now(P-2)

#programming #learning #java

Continued

1)Token

Tokens are the smallest elements of a program
They are fundamental building blocks of the program.

2)Keywords

Reserved words with predefined meanings.
Each keyword perform a specific function in a program.
Keywords cannot be used as variable names

These are some keywords which is in Java....

3)Identifiers:

Identifiers in Java are the names used to various elements in a program like variables,methods,classes,interfaces and Packages.
They make the code more readable way.

Examples:

Variable names: age, totalSum
Class names: Student, Employee
Method names: calculateArea(), displayDetails().

Rules for Naming Identifiers:

1.Must begin with a letter (A-Z or a-z), a dollar sign ($), or an underscore (_).
2.Cannot start with a digit (e.g., 1variable is invalid).
3.Can contain letters, digits (0-9), underscores, and dollar signs.
4.Cannot use Java reserved keywords (e.g., class, int, if).
5.Identifiers are case-sensitive (MyVariable and myvariable are different).

4)Literals:

literals are constant values that are directly assigned to variables
Literals may belong to any of the data type.
They represent fixed values of various data types, such as numbers, characters, strings, or boolean values. Types:

1.Integer Literals:
These are whole numbers without a fractional part.

Decimal (Base 10): Default format.
Octal (Base 8): Prefix with 0.
Hexadecimal (Base 16): Prefix with 0x or 0X.
Binary (Base 2): Prefix with 0b or 0B.

Example:
int decimal = 100; // Decimal literal
int octal = 0144; // Octal literal (equivalent to 100 in decimal)
int hex = 0x64; // Hexadecimal literal (equivalent to 100 in decimal)
int binary = 0b1100100; // Binary literal (equivalent to 100 in decimal)

2.Floating-Point Literals
These represent decimal numbers with a fractional part
Example:
double pi = 3.14159; // Standard notation
float gravity = 9.8f; // 'f' indicates a float literal
double exp = 1.5e2; // Scientific notation (150.0)

3.Character Literals:
A single character enclosed in single quotes (').
Example:
char letter = 'A'; // Character literal
char digit = '7'; // Character literal
char symbol = '$'; // Character literal

4.String Literals:
A sequence of characters enclosed in double quotes (").
Example:
String greeting = "Hello, World!"; // String literal
String empty = ""; // Empty string literal

5.Boolean Literals:
These represent true or false.
Example:
boolean isJavaFun = true; // Boolean literal
boolean isFishTasty = false; // Boolean literal

5)ASCII(American Standard Code for Information Interchange)

standardized system that assigns numeric codes to letters, digits, punctuation marks.
Each character is represented by a unique 7-bit binary number.
allows computers to store and communicate text data efficiently.

6)UNICODE(Universal character encoding standard)