Core Java Programming for Complete Beginners to Pro [2025]

Explore Java basics by mastering keywords, identifiers, literals, and primitive data types. Learn how access specifiers, modifiers, defaults, and naming rules shape Java programs.

Explore key Java fundamentals by answering common questions on exe vs class files, function versus method, Java bytecode, parameters and arguments, comments, Git, and Unicode.

learn why the Java main method is public and static, how the JVM invokes it, and how command line arguments are passed as a string array args.

Create objects in Java with the new keyword and constructors, and distinguish referenced from unreferenced objects while noting object state, behavior, and identity under JVM memory management.

this lecture shows that object references hold the base address, not the data, and demonstrates how passing a reference enables in-place data modification, unlike call by value.

Explore local variables in Java, declared inside a method or constructor, with lifetime limited to scope. They must be initialized before use and are declared with default access specifier.

Learn how the JVM allocates memory across the stack, heap, method area, native method area, and the PC register, and how instance variables are allocated and initialized in objects.

Learn how instance variables work in Java through a demo class, illustrating private data, default values, and access modifiers across objects.

Explore how static variables are initialized by the class loader at class loading time, ahead of main, and how static data is shared across instances, demonstrated with example outputs.

Explore final variables in Java, including how instance and static variables require initialization, auto initialization by the JVM or class loader, and how public static final constants are declared.

Discover how Java blocks work: static blocks run once at class loading time before main, while non-static blocks run for each object before the constructor, showing their execution order.

Explore static and non-static blocks in Java, showing class loading initializes static data, then sequential blocks execute; observe non-static blocks before constructors and object data updates.

this lecture explains wrapper classes in java and how they convert between strings and primitives using parse methods and toString for boolean, byte, short, int, long, float, double, and character.

Explore wrapper classes in Java, including boolean, byte, short, char, int, float, long, and double, and learn autoboxing and unboxing with practical constructor examples and string conversions.

Explore wrapper classes in Java by converting primitive types to strings and vice versa. Practice autoboxing and unboxing, and use parse and toString methods in hands-on demos.

Show how command line arguments in Java are passed to main as a String[] named args, with size equal to inputs (zero if none), illustrated by an Armstrong number example.

Learn to read a command line argument in java, convert it from string to int, and determine if the input is an Armstrong number using a digit cube sum loop.

Use Scanner class to take input from standard input in Java, including creating the Scanner with System.in, importing java.util.Scanner, and reading data with nextLine and nextInt/nextDouble.

Use the Scanner class to read a number from the keyboard and compute the sum of its digits with a modulo ten loop, then print the result.

Learn to take keyboard input using the data input stream class from java.io, constructing with system.in, reading lines with readLine, handling IO exception, and parsing to int or double.

Learn how to use the data input stream class from java.io to read keyboard input, convert it to integers with parseInt, and implement a prime number checker.

Learn the fundamentals of for, while, and do-while loops in Java with practical examples, including printing numbers, identifying even and odd numbers, and using break and continue in nested loops.

Demonstrate building a parity checker that prints even and odd numbers in a range using a while loop with input via scanner, and compare with for and do while loops.

Explore Java loops by implementing the same program with for, while, and do-while loops, using scanner input to determine and print whether numbers are even or odd.

Explore loops in Java by building a simple program that uses a while true loop, tests a break condition, and prints incremental values to show break behavior.

Explore loop concepts in Java using a practical example, including do-while and while loops, increment operators, break, and conditions to control program flow.

Demonstrates configuring for and while loops as outer and nested loops in Java, with a do-while inner loop. Produces 00012, illustrating execution flow and interview-ready loop patterns.

Explain the use of the continue statement in a labeled outer loop S1 within a nested for loop, showing how it skips iterations and prints values for i and j.

Demonstrates swapping two numbers using a third variable in java, by taking keyboard input with a scanner and showing values before and after the swap.

Learn to print number triangle patterns in Java with nested loops and user input, demonstrating outer and inner loops that form sequences like 112123123412345 and 332 with line breaks.

Learn to design a triangle pattern in Java using nested loops and a scanner to input the number of rows, printing stars or numbers per row.

Explore unary operators in Java for beginners, including seven types — unary plus, unary minus, increment, decrement, typecasting, bitwise inversion, and boolean complement — with practical examples.

Explore practical Java unary operators, including unary plus, unary minus, and pre/post increment and decrement, plus typecasting, auto conversion, and bitwise inversion and boolean complement operators, with hands-on code examples.

Explore bitwise operators in core java with examples of and, or, and xor on 8-bit words, plus short-circuit logical operators and the unary, binary, and ternary forms.

Learn how binary and ternary operators work in Java, including arithmetic and assignment nuances, short-circuit evaluation, and how type casting and operator differences resolve incompatible types.

Explore basic conditionals in Java, including if-else, boolean handling, and switch cases, with practical examples and differences from C, and modern string switch support.

Explain why the Java main method is static, as a class method called by the JVM by class name with no object, and that non-static main leads to runtime termination.

Learn how the public static void main(String[] args) serves as the Java program entry point, invoked by the class name without creating an instance, with final and other modifiers' effects.

Learn that you can overload the main method in Java. The Java virtual machine calls only the main with a string array parameter.

Declare constants in Java with public static final, not const, and ensure they are initialized. Java has no global variables; use static class variables accessed by class name.

Understand how command line arguments let a Java program receive input at runtime by the JVM creating a string array and passing it as the main method's args parameter.

Explore autoboxing and unboxing in Java, driven by wrapper classes for the eight primitive types introduced in JDK 1.5. See how primitives convert to wrapper objects and back through unboxing.

This lecture explains converting a string to int and back using the Integer wrapper class, showing two static methods for converting from string to int and from int to string.

Explore Java comments and their types, including single-line, multi-line, and document comments, and learn how the compiler skips them and how they explain variables, methods, and classes.

Define a class as a blueprint for creating objects and its attributes, fields, methods, and a constructor. Recognize that Java is an object oriented language with predefined classes in java.lang.

define an object as the instance of a class, carrying state, behavior, and identity. recognize that in java, object is the base class for every class.

Explore inheritance as a core object‑oriented concept, where a child class reuses the base class's properties and behavior, forming a maintainable hierarchy through extends and implements.

Explains polymorphism as multiple forms of an object in Java, covering compile time polymorphism (method overloading) and runtime polymorphism (method overriding) with early and dynamic binding.

Explore encapsulation as wrapping data and the methods that operate on it into a single unit to hide internal details and protect data from unauthorized access.

Explore typecasting of object references in Java with inheritance, showing that a base class reference can point to a child object and require casting to access child members.

Discover how the super keyword acts as a non-static reference to base members in inheritance. Use it to differentiate base and child variables, call base constructors, and invoke overridden methods.

Master method overriding in inheritance by redefining base method in a child with the same name, return type, and parameters, while noting static, private, and final methods cannot be overridden.

Explain how a Java abstract class is declared with the abstract keyword and cannot be instantiated; it may contain abstract and non-abstract methods, with abstract methods overridden by child classes.

Explore Java interfaces: the interface keyword, implicit abstract nature, and constants as public static final, with methods that are public abstract and interface offers static, default, and private variants.

Explain marker interfaces in Java as blank interfaces with no methods or variables, and illustrate how Cloneable in java.lang signals object cloning.

Differentiate abstract class and interface by noting that abstract class cannot support multiple inheritance. Interface supports multiple inheritance and defines only abstract, default, private, or static methods with constants.

Learn to print a triangle pattern in Java using nested loops and Scanner input, showing sequences from the current row to the total rows.

Design a multiplication table in Java by reading a number with a Scanner and printing results from 1 to 10 using System.out and a for loop.

Learn to generate the Fibonacci series up to a user defined range using Java, starting from 0 and 1, printing each value via a for loop and a temp swap.

Write a Java program to check whether a number is a palindrome by reversing digits with a scanner input and comparing it to the original.

Enter a number and determine if it is prime in Java by counting divisors from 1 to n using the Scanner, and print whether it is a prime or not.

Explore how Java arrays are data structures that hold primitive types or object references in zero-based indices, and learn declaration, construction, initialization, length, and array index out of bounds exception.

learn to read input from the keyboard using scanner, declare and initialize arrays with default values, print elements, and sort them in ascending order with Arrays.sort from java.util.

Explore java array concepts, including array of object references and two dimensional arrays, with memory layout, default null references, and initialization for string and user defined classes.

Explore array of object reference and two dimensional array in Java, including memory management, constructing EMP objects, and reading input with Scanner to populate and print array elements.

Learn to enter array elements from the keyboard, initialize the array, and determine the biggest and smallest values using a for loop and conditional checks.

Learn to find the second largest number in an array using Java by taking keyboard input with Scanner, initializing, and updating largest and second largest values with a for-each loop.

Discover how to reverse a Java array by swapping symmetric elements in place, after reading the size from keyboard, initializing elements, and printing the reversed array.

Enter array elements from the keyboard and find all pairs that sum to a given value using a static findPair method and nested loops.

Sort the array with the Arrays class, then remove duplicates from the sorted array by using a static remove method and Arrays.copyOf to resize the result.

Learn bubble sort by illustrating how the largest element moves to the end, using nested loops and swapping in a Java example, with arrays printed before and after sorting.

Discover how selection sort arranges an array in ascending order by repeatedly placing the smallest element at the front, with a hands-on Java example.

Explore linear searching, implement a Java linear search to find an element in an array, return its index or -1 when not found, and understand input handling and array traversal.

Learn binary search in Java by sorting an array and implementing a static binary search method that returns the index of a target or -1, using command line input.