Modern Java — Lambda Expressions & Stream API Pipelines (ల్యాంబ్డా & స్ట్రీమ్స్ ఆర్కిటెక్చర్)

import java.util.*;
import java.util.function.*;

public class FunctionalInterfacesAndLambdasDemo {
    public static void main(String[] args) {
        System.out.println("=== 1. PREDICATE (CONDITION CHECK) ===");
        Predicate<Integer> isEligibleForLoan = score -> score >= 750;
        Predicate<Integer> isVIP = score -> score >= 820;

        System.out.println("Credit Score 780 eligible? " + isEligibleForLoan.test(780));
        System.out.println("Credit Score 720 eligible? " + isEligibleForLoan.test(720));
        // Predicate Chaining (and, or, negate)
        Predicate<Integer> eligibleNonVIP = isEligibleForLoan.and(isVIP.negate());
        System.out.println("Score 780 is Eligible Non-VIP? " + eligibleNonVIP.test(780));

        System.out.println("
=== 2. FUNCTION (TRANSFORMATION) ===");
        Function<String, Integer> parseWordLength = String::length; // Method reference
        Function<Integer, Double> calculateGST = price -> price * 1.18;

        System.out.println("Length of 'Hyderabad': " + parseWordLength.apply("Hyderabad"));
        System.out.println("Price ₹1000 + 18% GST: ₹" + calculateGST.apply(1000));

        System.out.println("
=== 3. CONSUMER (SIDE EFFECT) ===");
        Consumer<String> auditLogger = msg -> System.out.println("🔔 [AUDIT]: " + msg);
        auditLogger.accept("User 'admin' changed production configuration.");

        System.out.println("
=== 4. SUPPLIER (LAZY GENERATION) ===");
        Supplier<String> sessionTokenGenerator = () -> "TOK-" + UUID.randomUUID().toString().substring(0, 8);
        System.out.println("Generated New Token 1: " + sessionTokenGenerator.get());
        System.out.println("Generated New Token 2: " + sessionTokenGenerator.get());
    }
}

import java.util.*;
import java.util.stream.Collectors;

public class StreamPipelineAnalyticsBenchmark {

    public record Employee(int id, String name, String dept, double salary) {}

    public static void main(String[] args) {
        System.out.println("=== STREAM PIPELINE ANALYTICS BENCHMARK ===");

        List<Employee> employees = List.of(
            new Employee(1, "Balaji", "Engineering", 125000),
            new Employee(2, "Suresh", "Product", 95000),
            new Employee(3, "Kavitha", "Engineering", 140000),
            new Employee(4, "Ramesh", "Finance", 80000),
            new Employee(5, "Anand", "Engineering", 110000),
            new Employee(6, "Divya", "Finance", 92000)
        );

        // 1. FILTER & MAP: ఇంజనీరింగ్ విభాగంలో ₹1,15,000 కంటే ఎక్కువ జీతం ఉన్నవారి పేర్లు
        List<String> topEngineers = employees.stream()
            .filter(e -> "Engineering".equals(e.dept()))
            .filter(e -> e.salary() > 115000)
            .map(Employee::name)
            .toList(); // Modern Java 16+
        System.out.println("టాప్ ఇంజనీర్లు: " + topEngineers);

        // 2. REDUCE: మొత్తం సంస్థ యొక్క శాలరీ బిల్లు
        double totalSalaryBill = employees.stream()
            .map(Employee::salary)
            .reduce(0.0, Double::sum);
        System.out.printf("మొత్తం జీతాల వ్యయం: ₹%,.2f%n", totalSalaryBill);

        // 3. GROUPING BY: డిపార్ట్‌మెంట్ వారిగా ఉద్యోగుల వర్గీకరణ
        Map<String, List<Employee>> employeesByDept = employees.stream()
            .collect(Collectors.groupingBy(Employee::dept));
        System.out.println("
--- డిపార్ట్‌మెంట్ వారిగా ఉద్యోగులు ---");
        employeesByDept.forEach((dept, list) -> 
            System.out.printf("  [%-12s] : %d ఉద్యోగులు%n", dept, list.size())
        );

        // 4. PARALLEL STREAM: సమాంతర గణన
        long highEarnersCount = employees.parallelStream()
            .filter(e -> e.salary() >= 100000)
            .count();
        System.out.println("
₹1 లక్ష కంటే ఎక్కువ జీతం ఉన్న ఉద్యోగుల సంఖ్య: " + highEarnersCount);
    }
}

import java.time.Instant;
import java.util.*;
import java.util.stream.Collectors;

public class StockMarketTradeStreamEngine {

    public enum TradeType { BUY, SELL }

    // Java 21 LTS ఇమ్యూటబుల్ ట్రేడ్ రికార్డ్
    public record Trade(
        String tradeId,
        String ticker,
        TradeType type,
        double price,
        int quantity,
        Instant timestamp
    ) {
        public double getTotalValue() {
            return price * quantity;
        }
    }

    public static void main(String[] args) {
        System.out.println("=== REAL-TIME STOCK TRADE STREAM ANALYTICS ENGINE ===");

        List<Trade> tradeBook = List.of(
            new Trade("TR-101", "TCS", TradeType.BUY, 3850.50, 100, Instant.now()),
            new Trade("TR-102", "INFY", TradeType.SELL, 1520.00, 250, Instant.now()),
            new Trade("TR-103", "RELIANCE", TradeType.BUY, 2910.00, 500, Instant.now()),
            new Trade("TR-104", "TCS", TradeType.BUY, 3860.00, 200, Instant.now()),
            new Trade("TR-105", "HDFCBANK", TradeType.SELL, 1450.00, 800, Instant.now()),
            new Trade("TR-106", "RELIANCE", TradeType.SELL, 2905.00, 150, Instant.now())
        );

        System.out.println("మొత్తం ఇన్కమింగ్ ట్రేడ్ ఆర్డర్లు: " + tradeBook.size());

        // 1. ₹5,00,000 కంటే ఎక్కువ విలువైన బిగ్-బ్లాక్ ట్రేడ్స్ (Block Deals)
        System.out.println("
🔥 --- BLOCK DEALS (> ₹5,00,000) ---");
        tradeBook.stream()
            .filter(t -> t.getTotalValue() >= 500000)
            .sorted(Comparator.comparingDouble(Trade::getTotalValue).reversed())
            .forEach(t -> System.out.printf("  [%s] %-8s | %-4s | Qty: %-4d | Total: ₹%,.2f%n",
                t.tradeId(), t.ticker(), t.type(), t.quantity(), t.getTotalValue()));

        // 2. టిక్కర్ వారీగా మొత్తం ట్రేడింగ్ వాల్యూమ్ గ్రూపింగ్ (Grouping & Summing)
        System.out.println("
📊 --- TICKER WISE TOTAL TURNOVER ---");
        Map<String, Double> turnoverByTicker = tradeBook.stream()
            .collect(Collectors.groupingBy(
                Trade::ticker,
                Collectors.summingDouble(Trade::getTotalValue)
            ));

        turnoverByTicker.forEach((ticker, turnover) -> 
            System.out.printf("  Ticker: %-10s -> Turnover: ₹%,.2f%n", ticker, turnover)
        );

        // 3. మార్కెట్ సమ్మరీ గణాంకాలు (DoubleSummaryStatistics)
        DoubleSummaryStatistics stats = tradeBook.stream()
            .collect(Collectors.summarizingDouble(Trade::getTotalValue));

        System.out.println("
📈 --- LIVE MARKET METRICS ---");
        System.out.printf("కనిష్ట ట్రేడ్ విలువ (Min) : ₹%,.2f%n", stats.getMin());
        System.out.printf("గరిష్ట ట్రేడ్ విలువ (Max) : ₹%,.2f%n", stats.getMax());
        System.out.printf("సగటు ట్రేడ్ విలువ  (Avg) : ₹%,.2f%n", stats.getAverage());
        System.out.printf("మొత్తం టర్నోవర్   (Total): ₹%,.2f%n", stats.getSum());
    }
}