1. Java Basics
Platform Independent: Java code is compiled to bytecode (.class files), which runs
on the JVM.
Strongly Typed: Variables must be declared with a type.
OOP Language: Follows Object-Oriented Programming concepts: Encapsulation,
Inheritance, Polymorphism, Abstraction.
🟠 2. Data Types
Primitive types:
int (4 bytes), float (4 bytes), double (8 bytes), char (2 bytes), boolean, byte,
short, long
Non-primitive types:
Classes, Strings, Arrays, Interfaces
🔵 3. Control Structures
Conditionals: if, else, switch
Loops: for, while, do-while, for-each
Break & Continue: Used for loop control
🟣 4. Object-Oriented Concepts
Class: Blueprint for objects
Object: Instance of a class
Constructor: Special method to initialize objects
Inheritance: extends keyword
Polymorphism: Method Overloading (same name, different params), Method Overriding
(subclass version)
Encapsulation: Using private fields + getters/setters
Abstraction: Using abstract classes or interface
🟡 5. Modifiers
Access Modifiers: public, private, protected, default (no modifier)
Other Modifiers: static, final, abstract, synchronized, transient
🔴 6. Exception Handling
try, catch, finally
throw: to throw an exception
throws: declares that a method may throw exceptions
Checked vs Unchecked exceptions
🟢 7. Arrays & Strings
Array: Fixed-size collection (int[] arr = new int[5];)
Platform Independent: Java code is compiled to bytecode (.class files), which runs
on the JVM.
Strongly Typed: Variables must be declared with a type.
OOP Language: Follows Object-Oriented Programming concepts: Encapsulation,
Inheritance, Polymorphism, Abstraction.
🟠 2. Data Types
Primitive types:
int (4 bytes), float (4 bytes), double (8 bytes), char (2 bytes), boolean, byte,
short, long
Non-primitive types:
Classes, Strings, Arrays, Interfaces
🔵 3. Control Structures
Conditionals: if, else, switch
Loops: for, while, do-while, for-each
Break & Continue: Used for loop control
🟣 4. Object-Oriented Concepts
Class: Blueprint for objects
Object: Instance of a class
Constructor: Special method to initialize objects
Inheritance: extends keyword
Polymorphism: Method Overloading (same name, different params), Method Overriding
(subclass version)
Encapsulation: Using private fields + getters/setters
Abstraction: Using abstract classes or interface
🟡 5. Modifiers
Access Modifiers: public, private, protected, default (no modifier)
Other Modifiers: static, final, abstract, synchronized, transient
🔴 6. Exception Handling
try, catch, finally
throw: to throw an exception
throws: declares that a method may throw exceptions
Checked vs Unchecked exceptions
🟢 7. Arrays & Strings
Array: Fixed-size collection (int[] arr = new int[5];)
