Unit 1: Primitive Types

  • Data Types: int, double, boolean, char
  • Variable Declaration: int x = 5;
  • Arithmetic: +, -, *, /, %, precedence rules (PEMDAS)
  • Casting: int to double, double to int (truncation)
  • Input: Scanner sc = new Scanner(System.in);
  • Output: System.out.println();

    Unit 2: Using Objects

  • Objects: Created with new
  • Strings: String str = “hello”;
  • Methods: length(), substring(), indexOf(), charAt()
  • Null References: null
  • Equality: == (reference), .equals() (content)
  • Math Class: Math.pow(), Math.sqrt(), Math.random()

    Unit 4: Iteration

  • Loops:
    • while(condition) { }
    • for(initialization; condition; update) { }
    • do { } while(condition);
  • Break/Continue: Exit or skip loop iteration
  • Nested Loops: Loop inside another loop
  • Loop Applications: Traversing arrays, searching, counting

    Unit 5: Writing Classes

  • Class Anatomy: Fields, methods, constructors
  • Constructor: Initializes object state
  • public ClassName(type parameter) { }
  • Accessors (Getters): Return field value
  • Mutators (Setters): Modify field value
  • Static Members: Shared across all instances
  • Encapsulation: Use private fields and public methods

    Unit 6: Array

  • Declaration: type[] arrayName = new type[size];
  • Access Elements: array[index]
  • Iteration: Use loops to traverse arrays
  • Common Operations: Finding max/min, sum, average
  • Bounds Checking: Avoid ArrayIndexOutOfBoundsException

    Unit 7: ArrayList

  • ArrayList Declaration: ArrayList list = new
  • ArrayList<>();
  • Methods:
    • add(), remove(), set(), get(), size()
  • Dynamic Resizing: Can grow or shrink as needed
  • Iteration: For-each or standard for loop
  • Autoboxing/Unboxing: Convert between primitives and wrapper objects

    Unit 8: 2D Arrays

  • Declaration: type[][] arrayName = new type[rows][cols];
  • Access Elements: array[row][col]
  • Iteration: Use nested loops for row-column traversal
  • Applications: Grids, matrices
  • Common Algorithms: Row-wise, column-wise processing

    Unit 9: Inheritance

  • Inheritance: class Subclass extends Superclass
  • Subclass: Inherits fields/methods from superclass
  • Method Overriding: Redefine superclass method in subclass
  • Super Keyword: Call superclass constructor/method
  • Polymorphism: Use superclass reference for subclass object
  • Object Class: All classes inherit from Object