Topics (Inprogress)

Here is a comprehensive list of Java topics that will be covered in the notes, categorized by difficulty level and subject area. The goal is to include every relevant topic with detailed explanations, examples, and best practices.

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1. Basics of Java

1. What is Java?
   • Features of Java (WORA, OOP, Rich API, etc.)
   • JVM, JRE, and JDK
2. Hello World Program
   • Compilation and Execution
3. Variables and Data Types
   • Primitive and Non-Primitive Data Types
   • Type Casting (Widening and Narrowing)
4. Operators in Java
   • Arithmetic, Relational, Logical, Bitwise, etc.
5. Input/Output in Java
   • Scanner and BufferedReader for input
   • Printing Output using System.out.println
6. Comments in Java
   • Single-line, Multi-line, and Documentation Comments

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2. Control Flow

1. Conditional Statements
   • if, else if, and else
   • Ternary Operator
2. Switch Case
   • Syntax and Fall-Through Behavior
3. Loops in Java
   • for, while, and do-while Loops
   • Enhanced for Loop
4. Break and Continue
5. Nested Loops

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3. Object-Oriented Programming (OOP)

1. Classes and Objects
   • Creating Classes and Objects
   • this Keyword
2. Constructors
   • Default, Parameterized, and Copy Constructors
3. Inheritance
   • super Keyword
   • Method Overriding
   • final Keyword in Inheritance
4. Polymorphism
   • Compile-Time Polymorphism (Method Overloading)
   • Runtime Polymorphism (Method Overriding)
5. Abstraction
   • Abstract Classes
   • Interfaces (Pre-Java 8 and Post-Java 8)
6. Encapsulation
   • Getters and Setters
   • Access Modifiers (private, protected, public, default)
7. Static and Non-Static Members
8. Nested and Inner Classes
9. Object Class Methods
   • toString, equals, hashCode, etc.

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4. Arrays and Strings

1. Arrays
   • Single-Dimensional and Multi-Dimensional Arrays
   • Array Manipulation (Arrays Class)
2. Strings
   • Immutable Nature of Strings
   • String Methods (charAt, substring, equals, etc.)
   • StringBuilder and StringBuffer
3. String Tokenization (split and StringTokenizer)

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5. Collections Framework

1. List Interface
   • ArrayList, LinkedList, Vector
2. Set Interface
   • HashSet, LinkedHashSet, TreeSet
3. Map Interface
   • HashMap, LinkedHashMap, TreeMap, Hashtable
4. Queue Interface
   • PriorityQueue, Deque
5. Collections Utility Class
   • Sorting, Searching, etc.

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6. Exception Handling

1. Types of Exceptions
   • Checked and Unchecked Exceptions
2. Try-Catch-Finally
3. Throw and Throws
4. Custom Exceptions

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7. Input/Output (I/O)

1. File Handling
   • Reading and Writing Files (FileReader, FileWriter, BufferedReader, etc.)
2. Serialization and Deserialization
3. Working with java.nio

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8. Multithreading and Concurrency

1. Thread Lifecycle
2. Creating Threads
   • Extending Thread Class
   • Implementing Runnable Interface
3. Synchronization
   • synchronized Keyword
   • Inter-thread Communication (wait, notify, notifyAll)
4. Executor Framework
   • ExecutorService and Thread Pools
5. Concurrency Utilities
   • CountDownLatch, CyclicBarrier, Semaphore, etc.

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9. Advanced Java Features

1. Lambda Expressions
2. Functional Interfaces (Predicate, Consumer, Supplier, etc.)
3. Stream API
   • Filtering, Mapping, Reducing, Collectors
4. Optional Class
5. Annotations
   • Built-in Annotations (@Override, @FunctionalInterface)
   • Custom Annotations
6. Reflection API
7. Generics

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10. Java 8 and Beyond

1. Features Introduced in Java 8
   • Default Methods in Interfaces
   • Stream API and Functional Programming
   • Date and Time API (LocalDate, LocalTime, Duration, etc.)
2. Enhancements in Later Versions
   • Module System (Java 9)
   • Var Keyword (Java 10)
   • Switch Expressions (Java 12+)
   • Records (Java 14)
   • Text Blocks (Java 15)

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11. JDBC (Java Database Connectivity)

1. Connecting Java with Databases
2. CRUD Operations
3. Prepared Statements
4. Transactions

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12. Design Patterns

1. Singleton Pattern
2. Factory Pattern
3. Builder Pattern
4. Observer Pattern
5. Dependency Injection

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13. Miscellaneous Topics

1. Enums
2. final, finally, and finalize
3. Garbage Collection
4. JVM Architecture
5. Working with Regular Expressions (Pattern and Matcher)
6. Debugging and Logging (Logger, Log4j)

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Java Basics

1. Data Types and Variables

Primitive Data Types

• Definition: Basic building blocks of data in Java, directly stored in memory.
• Types:
  • int: Stores integers (e.g., 1, -10). Example:

    int age = 25;
    

  • float: Stores decimal numbers with single precision. Example:

    float price = 19.99f;
    

  • double: Stores decimal numbers with double precision. Example:

    double salary = 12345.67;
    

  • char: Stores a single character. Example:

    char grade = 'A';
    

  • boolean: Stores true or false. Example:

    boolean isEligible = true;
    

Reference Data Types

• Definition: Store references to objects in memory.
• Examples:
  • String: Sequence of characters. Example:

    String name = "John Doe";
    

  • Arrays: Collection of elements of the same type. Example:

    int[] numbers = {1, 2, 3, 4, 5};
    

  • Objects: Instances of classes. Example:

    class Person {
        String name;
        int age;
    }
    
    Person p = new Person();
    p.name = "Alice";
    p.age = 30;
    

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2. Operators

Arithmetic Operators

• Used for mathematical operations.
• Example:

  int a = 10, b = 5;
  System.out.println(a + b); // Addition
  System.out.println(a - b); // Subtraction
  System.out.println(a * b); // Multiplication
  System.out.println(a / b); // Division
  System.out.println(a % b); // Modulus
  

Relational Operators

• Compare two values and return boolean results.
• Example:

  int x = 10, y = 20;
  System.out.println(x > y); // Greater than
  System.out.println(x < y); // Less than
  System.out.println(x == y); // Equal to
  System.out.println(x != y); // Not equal to
  

Logical Operators

• Combine multiple boolean expressions.
• Example:

  boolean a = true, b = false;
  System.out.println(a && b); // Logical AND
  System.out.println(a || b); // Logical OR
  System.out.println(!a);    // Logical NOT
  

Bitwise Operators

• Perform operations on bits.
• Example:

  int a = 5, b = 3; // Binary: a = 0101, b = 0011
  System.out.println(a & b); // Bitwise AND
  System.out.println(a | b); // Bitwise OR
  System.out.println(a ^ b); // Bitwise XOR
  

Unary Operators

• Operate on a single operand.
• Example:

  int a = 10;
  System.out.println(+a); // Unary plus
  System.out.println(-a); // Unary minus
  System.out.println(++a); // Increment
  System.out.println(--a); // Decrement
  

Ternary Operator

• Short-hand for if-else.
• Example:

  int a = 10, b = 20;
  int max = (a > b) ? a : b;
  System.out.println(max); // Prints 20
  

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3. Control Flow Statements

If-Else

• Conditional execution of code.
• Example:

  int age = 18;
  if (age >= 18) {
      System.out.println("Adult");
  } else {
      System.out.println("Minor");
  }
  

Switch-Case

• Multiple conditions with specific cases.
• Example:

  int day = 3;
  switch (day) {
      case 1: System.out.println("Monday"); break;
      case 2: System.out.println("Tuesday"); break;
      case 3: System.out.println("Wednesday"); break;
      default: System.out.println("Invalid day");
  }
  

Loops

For Loop

• Example:

  for (int i = 0; i < 5; i++) {
      System.out.println(i);
  }
  

While Loop

• Example:

  int i = 0;
  while (i < 5) {
      System.out.println(i);
      i++;
  }
  

Do-While Loop

• Example:

  int i = 0;
  do {
      System.out.println(i);
      i++;
  } while (i < 5);
  

Break and Continue

• Break: Exit the loop.
• Continue: Skip the current iteration.
• Example:

  for (int i = 0; i < 10; i++) {
      if (i == 5) break;
      if (i % 2 == 0) continue;
      System.out.println(i);
  }
  

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4. Input and Output

Scanner Class for User Input

• Example:

  import java.util.Scanner;
  
  public class InputExample {
      public static void main(String[] args) {
          Scanner scanner = new Scanner(System.in);
  
          System.out.println("Enter your name:");
          String name = scanner.nextLine();
  
          System.out.println("Enter your age:");
          int age = scanner.nextInt();
  
          System.out.println("Hello, " + name + ". You are " + age + " years old.");
      }
  }
  

Basic Output Using System.out

• Example:

  public class OutputExample {
      public static void main(String[] args) {
          System.out.println("Hello, World!"); // Print with newline
          System.out.print("This is inline");  // Print inline
      }
  }