07. స్విచ్ స్టేట్‌మెంట్స్ & మోడరన్ స్విచ్ ఎక్స్‌ప్రెషన్స్ (Switch Statements & Modern Switch Expressions)

public class WeeklySchedulePlanner {
    public static void main(String[] args) {
        System.out.println("==================================================");
        System.out.println("      WEEKLY SCHEDULE & WORKFLOW PLANNER ENGINE    ");
        System.out.println("==================================================");

        int dayNumber = 4; // Thursday

        // 1. Classic Switch Statement with Fall-through & Break
        System.out.print("[CLASSIC SWITCH] Day " + dayNumber + " is: ");
        switch (dayNumber) {
            case 1: System.out.println("Monday (Sprint Planning)"); break;
            case 2: System.out.println("Tuesday (Code Development)"); break;
            case 3: System.out.println("Wednesday (Mid-week Sync)"); break;
            case 4: System.out.println("Thursday (Code Review & QA)"); break;
            case 5: System.out.println("Friday (Deployment to Staging)"); break;
            case 6: case 7: System.out.println("Weekend (Recharge & Family)"); break;
            default: System.out.println("Invalid day index!");
        }

        // 2. Modern Java 14+ Switch Expression with Arrow Syntax
        String focusArea = switch (dayNumber) {
            case 1 -> "Sprint Planning & Architecture Roadmap";
            case 2, 3 -> "Core Feature Implementation (Full-Throttle)";
            case 4 -> "Automated Testing, Security Audit & PR Reviews";
            case 5 -> "Production Release & Monitoring";
            case 6, 7 -> "Offline (Personal Downtime)";
            default -> "Unassigned Day";
        };

        System.out.println("--------------------------------------------------");
        System.out.println("[MODERN SWITCH] Focus Area: " + focusArea);
        System.out.println("==================================================");
    }
}

public class OrderStatusTracker {
    public static void main(String[] args) {
        String trackingId   = "IND-DEL-984210";
        String currentStatus = "OUT_FOR_DELIVERY";

        System.out.println("--------------------------------------------------");
        System.out.println("       LOGISTICS ORDER DISPATCH & TRACKING        ");
        System.out.println("--------------------------------------------------");
        System.out.println("Tracking ID   : " + trackingId);
        System.out.println("Current Status: " + currentStatus);

        // String based Modern Switch Expression
        String customerAlert = switch (currentStatus.toUpperCase()) {
            case "ORDER_PLACED" -> "Your order has been confirmed by the merchant.";
            case "PROCESSING"   -> "Warehouse team is currently packaging your items.";
            case "SHIPPED"      -> "Package has left the central distribution hub.";
            case "OUT_FOR_DELIVERY" -> {
                String deliveryExecutive = "శ్రీకాంత్ యాదవ్ (Ph: +91 98765 43210)";
                yield "Out for delivery today! Agent: " + deliveryExecutive;
            }
            case "DELIVERED"    -> "Package delivered successfully! Thank you for shopping.";
            case "CANCELLED", "RETURNED" -> "Order was canceled. Refund initiated to source bank.";
            default -> "Unknown status code. Please contact customer care.";
        };

        System.out.println("--------------------------------------------------");
        System.out.println("Customer Notification:
  >> " + customerAlert);
        System.out.println("--------------------------------------------------");
    }
}

public class CloudBillingTierEngine {
    public static void main(String[] args) {
        String instanceTier = "ENTERPRISE_PRO";
        int activeHours     = 720; // Full 30 days month
        double discountRate = 0.10; // 10% Long-term commitment

        System.out.println("==================================================");
        System.out.println("      HYPER-SCALE CLOUD INFRASTRUCTURE BILLING    ");
        System.out.println("==================================================");

        // Modern Switch Expression evaluating hourly rate using yield
        double hourlyRateUSD = switch (instanceTier.toUpperCase()) {
            case "NANO", "MICRO" -> 0.015;
            case "SMALL", "MEDIUM" -> 0.045;
            case "LARGE", "XLARGE" -> 0.180;
            case "ENTERPRISE_PRO" -> {
                double baseCompute = 0.450; // 16 vCPU, 64GB RAM
                double dedicatedNetworkSla = 0.080; // 10 Gbps SLA
                yield baseCompute + dedicatedNetworkSla;
            }
            default -> {
                System.out.println("[WARN] Unrecognized tier. Defaulting to standard Micro.");
                yield 0.015;
            }
        };

        double grossCostUSD = activeHours * hourlyRateUSD;
        double discountUSD  = grossCostUSD * discountRate;
        double netCostUSD    = grossCostUSD - discountUSD;
        double netCostINR    = netCostUSD * 83.25;

        System.out.printf("  Selected Tier  : %s%n", instanceTier);
        System.out.printf("  Billing Rate   : $%.3f USD per hour%n", hourlyRateUSD);
        System.out.printf("  Uptime Hours   : %d hours%n", activeHours);
        System.out.println("--------------------------------------------------");
        System.out.printf("  Gross Compute  : $%,10.2f USD%n", grossCostUSD);
        System.out.printf("  Commitment Disc: -$%,9.2f USD (10%%)%n", discountUSD);
        System.out.println("--------------------------------------------------");
        System.out.printf("  TOTAL INVOICE  : $%,10.2f USD%n", netCostUSD);
        System.out.printf("  TOTAL IN INR   : ₹ %,10.2f INR%n", netCostINR);
        System.out.println("==================================================");
    }
}