Java Collection Hierarchy Explained

Day 41/200 - Java Learning Journey 🌱 ✨ Sharing what I learned today in Java. 🔆Learn a little every day, and one day you will realize how far you’ve come. 📚 Today I learned about Conditional Statements in java Today's Topic: Conditional Statements (if) 📍 Conditional Statements : 👉 These are also known as Decision Making Statements. 📍 If: 👉 The condition which is passed within the if will always check the boolean values and also the resultant will be boolean value. 👉 It is used to check only the one condition. 👉 Executes a block of code only if the condition is true. 👉 Syntax: if (condition){ //stmts } 📌 if(condition) without curly braces ,in that time the condition will be applied to the first line of the statement. Example 1: Checking if a number is positive or not. public class IfExample {    public static void main(String[] args) {    int number = 10;      if (number > 0) { // Checks if the number is greater than 0        System.out.println("The number is positive.");      }      System.out.println("End of program.");    } } O/p: The number is positive. End of program. Example 2: if Statement Skipping Execution. public class IfExample {    public static void main(String[] args) {      int number = -5;      if (number > 0) { // This condition is false        System.out.println("The number is positive.");      }      System.out.println("End of program.");    } } O/p: End of program. #Java#DailyLearning#Consistency#ConditionalStatements#Meghana M#10000 Coders#

Exception Handling in Java – My Learning Journey Today, I explored one of the most important concepts in Java – Exception Handling. 📌 What is an Exception? An exception is an unusual activity that occurs during the execution of a program due to faulty input, leading to abrupt termination. 💡 For example: When we divide a number by zero, the program stops immediately, and the remaining lines are not executed. This is called abrupt termination. ⚙️ Key Understanding - Exceptions do not occur at compile time - They occur during runtime (execution time) - When an exception happens:  - An exception object is created  - It is sent to the runtime system  - If no handling is present → Default Exception Handler terminates the program 🛠️ How to Handle Exceptions? We use try-catch blocks to handle exceptions and ensure smooth program execution. ✔️ Risky code is placed inside "try" ✔️ Handling logic is written in "catch" This helps in avoiding abrupt termination and allows the program to continue normally. 🔁 Multiple Catch Blocks We can use multiple "catch" blocks for a single "try". 👉 Important rules: - Only one catch block executes based on the exception - Always write specific exceptions first - Keep generic exception (Exception e) at the end 📚 Types of Exceptions I Learned - Arithmetic Exception (e.g., division by zero) - Negative Array Size Exception - Input Mismatch Exception - Array Index Out of Bounds Exception - Null Pointer Exception 🎯 Key Takeaway Exception handling helps us prevent abrupt termination and ensures the program runs smoothly and safely. 💭 Learning Java step by step and building strong fundamentals in OOP and error handling! #Java #ExceptionHandling #Programming #CodingJourney #OOP #Learning #SoftwareDevelopment

Day 44/200 - Java Learning Journey 🌱 ✨ Sharing what I learned today in Java. 🔆Your only limit is your mindset. 📚 Today I learned about Conditional Statements in java.(switch) Today's Topic: Conditional Statements(switch) 📍 switch: 👉 switch is an alternative for else-if. 👉 syntax: switch (expression) {    case value1:      // Code to execute if expression == value1      break;    case value2:      // Code to execute if expression == value2       break;    case value3:      // Code to execute if expression == value3      break;    default:      // Code to execute if no case matches } Example: public class SwitchExample {    public static void main(String[] args) {      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;        case 4:          System.out.println("Thursday");          break;        case 5:          System.out.println("Friday");          break;        default:          System.out.println("Weekend");      }    } } Output: Wednesday #Java#DailyLearning#Consistency#ConditionalStatements#switch#Meghana M#10000 Coders#

🚀 Day 22/100 – Java Learning Series Today I explored important looping and control concepts in Java, along with handling user input in programs. 🔹 while Loop The while loop executes a block of code as long as a condition remains true. It is useful when the number of iterations is not known beforehand. Syntax: while(condition){ // code } 🔹 do-while Loop The do-while loop is similar to the while loop, but it executes the code at least once, even if the condition is false. Syntax: do{ // code } while(condition); 🔹 Jumping Statements Jumping statements control the flow of loops and program execution. ✔ break – terminates the loop immediately ✔ continue – skips the current iteration and moves to the next ✔ return – exits from a method 🔹 Scanner Class The Scanner class (from java.util package) is used to take input from the user during program execution. Example: import java.util.Scanner; Scanner sc = new Scanner(System.in); int num = sc.nextInt(); 💡 Key Learning: Combining loops + jumping statements + user input helps build interactive and dynamic Java programs. Consistency in learning is the path to mastering programming. 💻🔥 #Java #JavaProgramming #CodingJourney #LearnJava #Programming #SoftwareDevelopment #JavaDeveloper #100DaysOfCode #10000 Coders #Meghana M

Day 55/200 - Java Learning Journey 🌱 ✨ Sharing what I learned today in Java. 🔆Every day is a new opportunity to improve your skills and expand your mindset. 📚 Today I learned about constructor chaining in Java Today's Topic: constructor chaining 📌 constructor chaining: 👉 Calling one constructor from another constructor is known as constructor chaining. 👉 constructor chaining is achieved by the this( ) call within the same class. 👉 constructor chaining is achieved by the super( ) call from the parent class. 👉 this( ) and super( ) must be the first statement inside the constructor. 👉 Only one (this() or super()) can be used in a constructor, not both. 👉 If we dont mention super( ) keyword in child class constructor,the JVM will give automatically the super( ) class for the constructor. 👉 whenever we use the keyword known as extends, the JVM automatically give super( ) class. 👉 If there are parameterized constructor in parent class manually we need to call those constructor by using super( ) class with parameters in child class constructor, at that time JVM will not give super( ) class. #Java#DailyLearning#Consistency#Constructor#ConstructorChaining#Meghana M#10000 Coders#

Day 43/200 - Java Learning Journey 🌱 ✨ Sharing what I learned today in Java. 🔆Dream big, start small, act now. 📚 Today I learned about Conditional Statements in java. Today's Topic: Conditional Statements (else-if) 📍 Else-if: 👉 It will be used when we have more than 2 condition to be checked. 👉 If the first if condition is false, Java checks the else if condition. 👉 Syntax: if(condition1) {    // Executes if condition1 is true } else if(condition2) {    // Executes if condition1 is true } else if(condition3) {    // Executes if condition1 is true } else {    // Executes if all above conditions are false } 👉 In if-else ,else-if "else" is an optional but better to follow for readability purpose. 👉 In both if-else ,else-if block "if" block is mandatory. Example: Grade Checker public class GradeCheck {    public static void main(String[] args) {      int marks = 75;      if (marks >= 90) {        System.out.println("Grade: A");      } else if (marks >= 75) {        System.out.println("Grade: B");      } else if (marks >= 60) {        System.out.println("Grade: C");      } else if (marks >= 40) {       System.out.println("Grade: D");      } else {       System.out.println("Grade: F (Fail)");      }    System.out.println("End of program.");    } } Ouput: Grade: B End of program. #Java#DailyLearning#Consistency#Else-if#ConditionalStatements#Meghana M#10000 Coders#

🚀 Day 30 | Core Java Learning Journey 📌 Topic: Map Hierarchy in Java Today, I explored the Map Hierarchy in Java Collections Framework — understanding how different Map interfaces and classes are structured and related. 🔹 What is Map in Java? ✔ Map is an interface that stores key-value pairs ✔ Each key is unique and maps to a specific value ✔ It is part of java.util package 🔹 Map Hierarchy (Understanding Structure) ✔ Map (Root Interface) ⬇ ✔ SortedMap (extends Map) ⬇ ✔ NavigableMap (extends SortedMap) ⬇ ✔ TreeMap (implements NavigableMap) 🔹 Important Implementing Classes ✔ HashMap • Implements Map • Does NOT maintain order • Allows one null key ✔ LinkedHashMap • Extends HashMap • Maintains insertion order ✔ TreeMap • Implements NavigableMap • Stores data in sorted order • Does NOT allow null key ✔ Hashtable • Implements Map • Thread-safe (synchronized) • Does NOT allow null key/value 🔹 Key Differences ✔ HashMap → Fast, no ordering ✔ LinkedHashMap → Maintains insertion order ✔ TreeMap → Sorted data ✔ Hashtable → Thread-safe but slower 📌 When to Use What? ✅ Use HashMap → when performance is priority ✅ Use LinkedHashMap → when insertion order matters ✅ Use TreeMap → when sorting is required ✅ Use Hashtable → when thread safety is needed 💡 Key Takeaway: Understanding Map hierarchy helps in choosing the right data structure based on use-case rather than just coding blindly. 🙏 Special thanks to Vaibhav Barde Sir for the guidance! 🔥 #CoreJava #JavaLearning #JavaDeveloper #Map #HashMap #TreeMap #LinkedHashMap #Hashtable #JavaCollections #Programming #LearningJourney

🚀 Exploring Built-in Methods of ArrayList in Java As part of my continuous learning in Java, I explored the powerful built-in methods of ArrayList that make data handling efficient and flexible. Understanding these methods is essential for writing clean and optimized code. Here’s a quick overview of some commonly used ArrayList methods 👇 🔹 1. add() Adds an element to the list list.add("Java"); 🔹 2. add(index, value) Inserts an element at a specific position list.add(1, "Python"); 🔹 3. addAll() Adds all elements from another collection list.addAll(otherList); 🔹 4. retainAll() Keeps only common elements between two collections list.retainAll(otherList); 🔹 5. removeAll() Removes all elements present in another collection list.removeAll(otherList); 🔹 6. set() Replaces an element at a specific index list.set(0, "C++"); 🔹 7. get() Retrieves an element by index list.get(0); 🔹 8. size() Returns the number of elements list.size(); 🔹 9. trimToSize() Trims capacity to match current size list.trimToSize(); 🔹 10. isEmpty() Checks if the list is empty list.isEmpty(); 🔹 11. contains() Checks if an element exists list.contains("Java"); 🔹 12. indexOf() Returns the first occurrence index list.indexOf("Java"); 🔹 13. lastIndexOf() Returns the last occurrence index list.lastIndexOf("Java"); 🔹 14. clear() Removes all elements from the list list.clear(); 🔹 15. subList(start, end) Returns a portion of the list list.subList(1, 3); 💡 Key Takeaway: Mastering these built-in methods helps in efficiently managing collections and solving real-world problems with ease. Consistency in practicing such concepts builds a strong foundation in Java development 💻✨ #Java #ArrayList #CollectionsFramework #Programming #Developers #LearningJourney #CodingSkills #KeepGrowing TAP Academy

🚀 Day 29 | Core Java Learning Journey 📌 Topic: TreeSet in Java Today, I learned about TreeSet, an important class in the Java Collections Framework used when we need sorted and unique elements. 🔹 TreeSet in Java ✔ TreeSet is a class that implements NavigableSet ✔ It also indirectly implements SortedSet and Set ✔ Introduced in JDK 1.2 ✔ Stores unique elements only (no duplicates allowed) 🔹 Data Structure Used ✔ Based on Self-Balancing Binary Search Tree (Red-Black Tree) ❗ (important correction) ✔ Elements are stored in sorted order 🔹 Key Features ✔ Does NOT follow insertion order ✔ Follows natural sorting order (default) ✔ Allows custom sorting using Comparator ✔ Does NOT allow null elements ❌ ✔ Stores homogeneous data (same type, for proper comparison) 📌 Important Methods • add() – add element • remove() – delete element • contains() – check element • first() – returns first (smallest) element • last() – returns last (largest) element • higher() – next greater element • lower() – next smaller element 📌 Performance ✔ Operations like add, remove, search → O(log n) 📌 When to Use TreeSet? ✔ When you need: ✅ Sorted data ✅ Unique elements ✅ Range-based operations 💡 Note: Unlike HashSet, TreeSet focuses on sorting rather than speed. 🙏 Special thanks to Vaibhav Barde Sir for the guidance! 🔥 #CoreJava #JavaLearning #JavaDeveloper #TreeSet #SortedSet #NavigableSet #JavaCollections #Programming #LearningJourney

🚀 Day 27 | Core Java Learning Journey 📌 Topic: Vector & Stack in Java Today, I learned about Vector and Stack, two important Legacy Classes in Java that are part of the early Java library and later became compatible with the Java Collections Framework. 🔹 Vector in Java ✔ Vector is a legacy class that implements the List interface ✔ Data structure: Growable (Resizable) Array ✔ Maintains insertion order ✔ Allows duplicate elements ✔ Allows multiple null values (not "NILL" ❌ → correct term is null ✔) ✔ Can store heterogeneous objects (different data types using Object) ✔ Synchronized by default (thread-safe, but slower than ArrayList) 📌 Important Methods of Vector • add() – add element • get() – access element • remove() – delete element • size() – number of elements • capacity() – current capacity of vector 💡 Note: Due to synchronization overhead, ArrayList is preferred in modern Java. 🔹 Stack in Java ✔ Stack is a subclass (child class) of Vector ✔ It is also a Legacy Class ✔ Data structure: LIFO (Last In, First Out) 📌 Core Methods of Stack • push() – add element to top • pop() – remove top element • peek() – view top element without removing 📌 Additional Useful Methods • isEmpty() – check if stack is empty • search() – find element position 💡 Note: In modern Java, Deque (ArrayDeque) is preferred over Stack for better performance. 📌 Key Difference: Vector vs Stack ✔ Vector → General-purpose dynamic array ✔ Stack → Specialized for LIFO operations 💡 Understanding these legacy classes helps in learning how Java data structures evolved and why modern alternatives are preferred today. Special thanks to Vaibhav Barde Sir for the guidance! #CoreJava #JavaLearning #JavaDeveloper #Vector #Stack #JavaCollections #Programming #LearningJourney