Java Language Fundamentals (SCJP)

Key Topics

1. Introduction to SCJP

• SCJP stands for Sun Certified Java Programmer.
• Covers core Java concepts.
• Emphasis on language features, syntax, and structures.

2. Language Fundamentals

Keywords

• Reserved words in Java that have predefined meanings in the language.
• Examples: int, boolean, char, class, public, final, etc.

Identifiers

• Names given to various program elements such as variables, methods, classes, etc.
• Must begin with a letter, currency character ($), or underscore (_).
• Cannot start with a number.

Data Types

• Primitive Types: byte, short, int, long, float, double, char, boolean.
• Reference Types: Objects and arrays.

Literals

• Constant values assigned to variables.
• Types: integer literals, floating-point literals, boolean literals, character literals, and string literals.

3. Syntax and Code Structure

Classes and Interfaces

• Class: Blueprint from which individual objects are created. Syntax: class ClassName {}
• Interface: Abstract type used to specify behaviors that classes must implement. Syntax: interface InterfaceName {}

Methods

• Blocks of code that perform a specific task and are defined within a class.
• Method structure: modifiers, return type, method name, parameter list, method body.

4. Variable Scope

Instance Variables

• Declared in a class, but outside any method, constructor, or block. They are instance-specific.

Class Variables (Static Variables)

• Declared with the static modifier.
• Shared among all instances of a class.

Local Variables

• Declared within a method, constructor, or block.
• Only accessible within the declared scope.

Parameters

• Variables passed to methods as input.

Summary

• Understanding these fundamentals is crucial for SCJP.
• Emphasis on syntax, data types, variables, and program structure.