🔥 Interface Mastery Assignments (Java)

1. Comparable

👉 Assignment:

• Create a Student class (id, name, marks).
• Implement Comparable<Student> to sort by marks.
• Store students in an ArrayList, sort using Collections.sort(), and print.

✔️ Expected Learning: Natural ordering, compareTo(), sorting with Comparable.

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2. Comparator

👉 Assignment:

• Extend previous Student example.

• Write 3 Comparators:

  1. Sort by name
  2. Sort by id
  3. Sort by marks descending

• Use Collections.sort(list, comparator) and test all.

✔️ Learning: Multiple sorting strategies.

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3. Cloneable

👉 Assignment:

• Create a Book class (title, author, price).
• Implement Cloneable and override clone().
• Perform shallow copy and show how changes affect both.
• Then implement deep copy (if Book contains another object like Publisher).

✔️ Learning: Shallow vs Deep cloning.

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4. Serializable

👉 Assignment:

• Create Employee class (id, name, salary).
• Serialize object → save to file.
• Deserialize it back → read from file.
• Show what happens when you mark a field transient.

✔️ Learning: Object persistence, transient keyword.

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5. Runnable

👉 Assignment:

• Create a PrintTask class that implements Runnable.
• Thread should print numbers from 1–10 with sleep.
• Start multiple threads concurrently.

✔️ Learning: Multithreading basics.

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6. Callable

👉 Assignment:

• Create a FactorialTask class implementing Callable<Long>.
• Use ExecutorService with Future to calculate factorial.
• Submit multiple tasks and print results.

✔️ Learning: Callable vs Runnable, return values from thread.

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7. Iterable & Iterator

👉 Assignment:

• Create a custom MyArray<T> collection.
• Implement Iterable<T>.
• Write your own Iterator to traverse elements.
• Test with for-each loop.

✔️ Learning: Custom collections, iteration mechanics.

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8. Collection Interfaces (List, Set, Map, Queue)

👉 Assignment:

• Take List<Student> → demonstrate duplicates allowed + ordering.
• Convert to Set<Student> → remove duplicates.
• Use Map<Integer, String> for student rollNo → name mapping.
• Use Queue<String> for ticket booking system simulation.

✔️ Learning: Collection framework fundamentals.

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9. AutoCloseable & Closeable

👉 Assignment:

• Create a class MyResource implementing AutoCloseable.
• Inside close(), print "Resource Closed".
• Use it inside try-with-resources block.

✔️ Learning: Resource management.

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10. Remote (RMI)

👉 Assignment:

• Create a simple RMI project:

  • Interface Calculator (extends Remote) with add, sub methods.
  • Implement it on server side.
  • Call from client.

✔️ Learning: Remote Method Invocation basics.

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11. EventListener

👉 Assignment:

• Create a custom ButtonClickListener interface extending EventListener.
• Class Button should register listeners & notify them on click.
• Test by adding multiple listeners.

✔️ Learning: Event-driven programming.

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12. Stream

👉 Assignment:

• Create a List<Employee>.

• Use Stream API to:

  1. Filter employees with salary > 50k.
  2. Convert names to uppercase.
  3. Sort by salary.
  4. Collect into a new List.

✔️ Learning: Fluent API + Stream operations.

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🚀 Final Real-World Project Assignment

👉 Build a Mini E-commerce System using interfaces:

• Product interface → classes Book, Electronics.
• Payment interface → classes CreditCardPayment, UPIPayment.
• Discount interface → different discount strategies.
• Use Comparable for sorting products by price.
• Use Serializable to save cart state.
• Use Runnable for sending confirmation emails in background.

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