Java Assessment(Tanishq Gandhi)

assignment/Eight.java

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+public class Eight {
+    public static void main(String[] args) {
+        long id = 101L;
+        String sql = """
+                SELECT id, name
+                FROM users
+                WHERE id = %d
+                AND status = 'ACTIVE'
+                ORDER BY name ASC;
+                """;
+        String finalQuery = sql.formatted(id);
+        System.out.println(finalQuery);
+    }
+}

assignment/Fifth.java

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+import java.util.Optional;
+
+record Users(String name, boolean isActive) {}
+
+public class Fifth {
+    public static void main(String[] args) {
+        String targetId = "user123";
+
+        findUser(targetId)
+                .filter(Users::isActive)
+                .map(Users::name)
+                .ifPresentOrElse(
+                        System.out::println,
+                        () -> System.out.println("User not found")
+                );
+    }
+
+    static Optional<Users> findUser(String id) {
+        if ("user123".equals(id)) {
+            return Optional.of(new Users("Ansh", false));
+        }
+        return Optional.empty();
+    }
+}

assignment/First.java

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+interface NotificationService {
+    void send(String message);
+
+    default void sendWithRetry(String message, int retries) {
+        for (int i = 1; i <= retries; i++) {
+            try {
+                send(message);
+                return;
+            } catch (Exception e) {
+                System.out.println("Attempt " + i + " failed.");
+            }
+        }
+    }
+}
+
+public class First {
+    public static void main(String[] args) {
+        NotificationService service = (msg) -> {
+            if (Math.random() > 0.5) throw new RuntimeException();
+            System.out.println("Sent: " + msg);
+        };
+
+        service.sendWithRetry("Quick Test", 3);
+    }
+
+}

assignment/Fourth.java

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+import java.util.List;
+import java.util.function.Predicate;
+
+public class Fourth {
+    public static void main(String[] args) {
+        List<Integer> numbers = List.of(-10, -5, 0, 2, 4, 7, 10, 15);
+
+        Predicate<Integer> isPositive = n -> n > 0;
+        Predicate<Integer> isEven = n -> n % 2 == 0;
+
+        Predicate<Integer> isPositiveEven = isPositive.and(isEven);
+
+        numbers.stream()
+                .filter(isPositiveEven)
+                .forEach(System.out::println);
+
+    }
+}

assignment/Second.java

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+@FunctionalInterface
+interface StringValidator {
+    boolean check(String s);
+}
+
+public class Second {
+    public static void main(String[] args) {
+        String input = "Java17";
+
+        validate(input, s -> !s.isEmpty());
+
+        validate(input, s -> s.length() > 5);
+
+        validate(input, s -> Character.isUpperCase(s.charAt(0)));
+    }
+
+    static void validate(String val, StringValidator validator) {
+        System.out.println("Input: " + val + " | Result: " + validator.check(val));
+    }
+}

assignment/Seventh.java

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+sealed interface Payment permits CardPayment, UpiPayment {}
+
+final class CardPayment implements Payment {
+    String number = "1234-5678";
+}
+
+final class UpiPayment implements Payment {
+    String id = "user@upi";
+}
+
+public class Seventh {
+    public static void main(String[] args) {
+        Payment pay1 = new CardPayment();
+        Payment pay2 = new UpiPayment();
+
+        process(pay1);
+        process(pay2);
+    }
+
+    public static void process(Payment p) {
+        if (p instanceof CardPayment c) {
+            System.out.println("Using Card: " + c.number);
+        } else if (p instanceof UpiPayment u) {
+            System.out.println("Using UPI: " + u.id);
+        }
+    }
+}

assignment/Sixth.java

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+import java.util.HashSet;
+import java.util.Set;
+
+record Employee(long id, double salary) {
+    private static long idGenerator = 100;
+    private static final Set<Long> uniqueIds = new HashSet<>();
+
+    public Employee {
+        if (salary <= 0) throw new IllegalArgumentException("Salary must be positive!");
+        uniqueIds.add(id);
+    }
+
+    public static Employee create(double salary) {
+        return new Employee(++idGenerator, salary);
+    }
+
+    public static int getUniqueEmployeeCount() {
+        return uniqueIds.size();
+    }
+
+    public static Set<Long> getAllIds() {
+        return uniqueIds;
+    }
+}
+
+public class Sixth {
+    public static void main(String[] args) {
+        Employee emp1 = Employee.create(50000.0);
+        Employee emp1Updated = new Employee(emp1.id(), 60000.0);
+        Employee emp2 = Employee.create(75000.0);
+
+        System.out.println("Total Unique IDs: " + Employee.getUniqueEmployeeCount());
+        System.out.println("List of Employee IDs: " + Employee.getAllIds());
+
+        System.out.println(emp1.hashCode());
+        System.out.println(emp1Updated.hashCode());
+    }
+}

assignment/Third.java

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+import java.util.List;
+
+class User {
+    private String name;
+    private int age;
+
+    public User(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    public String getName() { return name; }
+    public int getAge() { return age; }
+}
+
+public class Third {
+    public static void main(String[] args) {
+        List<User> users = List.of(
+                new User("Tanishq", 22),
+                new User("Ansh", 17),
+                new User("Priyanshu", 25),
+                new User("Akash", 40)
+        );
+
+        List<String> result = users.stream()
+                .filter(u -> u.getAge() >= 18)
+                .map(User::getName)
+                .map(String::toUpperCase)
+                .sorted()
+                .toList();
+
+        System.out.println(result);
+    }
+}