# 📚 Java Programming Language – Part 2/10: Operators & Control Flow
#Java #Programming #OOP #ControlFlow #Coding

Welcome to Part 2 of our Java series! Today we'll explore operators and control flow structures.

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## 🔹 Java Operators Overview
Java provides various operators for:
- Arithmetic calculations
- Logical decisions
- Variable assignments
- Comparisons

### 1. Arithmetic Operators

int a = 10, b = 3;
System.out.println(a + b);  // 13 (Addition)
System.out.println(a - b);  // 7 (Subtraction)
System.out.println(a * b);  // 30 (Multiplication)
System.out.println(a / b);  // 3 (Division - integer)
System.out.println(a % b);  // 1 (Modulus)
System.out.println(a++);    // 10 (Post-increment)
System.out.println(++a);    // 12 (Pre-increment)

### 2. Relational Operators

System.out.println(a == b); // false (Equal to)
System.out.println(a != b);  // true (Not equal)
System.out.println(a > b);   // true (Greater than)
System.out.println(a < b);   // false (Less than)
System.out.println(a >= b);  // true (Greater or equal)
System.out.println(a <= b);  // false (Less or equal)

### 3. Logical Operators

boolean x = true, y = false;
System.out.println(x && y);  // false (AND)
System.out.println(x || y);  // true (OR)
System.out.println(!x);      // false (NOT)

### 4. Assignment Operators

int c = 5;
c += 3;  // Equivalent to c = c + 3
c -= 2;  // Equivalent to c = c - 2
c *= 4;  // Equivalent to c = c * 4
c /= 2;  // Equivalent to c = c / 2

---

## 🔹 Control Flow Statements
Control the execution flow of your program.

### 1. if-else Statements

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

### 2. Ternary Operator

String result = (age >= 18) ? "Adult" : "Minor";
System.out.println(result);

### 3. switch-case Statement

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

### 4. Loops
#### while Loop

int i = 1;
while (i <= 5) {
    System.out.println(i);
    i++;
}

#### do-while Loop

int j = 1;
do {
    System.out.println(j);
    j++;
} while (j <= 5);

#### for Loop

for (int k = 1; k <= 5; k++) {
    System.out.println(k);
}

#### Enhanced for Loop (for-each)

int[] numbers = {1, 2, 3, 4, 5};
for (int num : numbers) {
    System.out.println(num);
}

---

## 🔹 Break and Continue
Control loop execution flow.

// Break example
for (int i = 1; i <= 10; i++) {
    if (i == 5) {
        break;  // Exit loop
    }
    System.out.println(i);
}

// Continue example
for (int i = 1; i <= 10; i++) {
    if (i % 2 == 0) {
        continue;  // Skip even numbers
    }
    System.out.println(i);
}

---

## 🔹 Practical Example: Number Guessing Game

import java.util.Scanner;
import java.util.Random;

public class GuessingGame {
    public static void main(String[] args) {
        Random rand = new Random();
        int secretNumber = rand.nextInt(100) + 1;
        Scanner scanner = new Scanner(System.in);
        int guess;
        
        do {
            System.out.print("Guess the number (1-100): ");
            guess = scanner.nextInt();
            
            if (guess < secretNumber) {
                System.out.println("Too low!");
            } else if (guess > secretNumber) {
                System.out.println("Too high!");
            }
        } while (guess != secretNumber);
        
        System.out.println("Congratulations! You guessed it!");
        scanner.close();
    }
}

---

### 📌 What's Next?
In Part 3, we'll cover:
➡️ Methods and Functions
➡️ Method Overloading
➡️ Recursion

#JavaProgramming #ControlFlow #LearnToCode 🚀

### 4. Switch Expressions (Java 14)

String dayType = switch (day) {
    case "Mon", "Tue", "Wed", "Thu", "Fri" -> "Weekday";
    case "Sat", "Sun" -> "Weekend";
    default -> throw new IllegalArgumentException();
};

---

## 🔹 Practical Example: Employee Processing

public class Employee {
    private String name;
    private String department;
    private double salary;
    // Constructor, getters
}

List<Employee> employees = // ... initialized list

// Stream processing example
Map<String, Double> avgSalaryByDept = employees.stream()
    .collect(Collectors.groupingBy(
        Employee::getDepartment,
        Collectors.averagingDouble(Employee::getSalary)
    ));

// Modern Java features
List<String> highEarners = employees.stream()
    .filter(e -> e.salary() > 100000)
    .map(Employee::name)
    .sorted()
    .toList();  // Java 16+ toList()

System.out.println(avgSalaryByDept);
System.out.println(highEarners);

---

## 🔹 Best Practices
1. Prefer immutability with records and unmodifiable collections
2. Use Optional instead of null checks
3. Favor functional style with streams for data processing
4. Keep lambdas short and readable
5. Adopt modern features gradually in existing codebases

---

### 🎉 Congratulations!
You've completed our 10-part Java series! Here's what we covered:
1. Java Basics
2. Operators & Control Flow
3. Methods & Functions
4. OOP Concepts
5. Inheritance & Polymorphism
6. Interfaces & Abstract Classes
7. Packages & Access Modifiers
8. Exception Handling
9. Collections Framework
10. Streams & Modern Features

#JavaProgramming #CompleteCourse #ModernJava 🚀

What's next?
➡️ Build real projects
➡️ Explore frameworks (Spring, Jakarta EE)
➡️ Learn design patterns
➡️ Contribute to open source

Happy coding! 👨‍💻👩‍💻