Java Tutorial

Write a method isAdult(int age) that returns true for 18 or above.

Find the highest mark in the array.

Count the vowels in a string.

Add a withdraw(double amount) method that only withdraws if the balance is enough.

Add a constructor Product(String name) with a default price of 1.0.

Make an Employee class whose salary can only increase via giveRaise(percent).

Create a CurrentAccount that overrides monthlyFee() to return 100.

Add a WalletPayment that returns "Paid from wallet".

Create an EmailNotifier that implements Notifier and prints "Email to …".

Which access modifier lets only classes in the same package use a method?

Parse "abc" with Integer.parseInt and print "Invalid number" instead of crashing.

Count how many times each word appears in a list.

Write a generic method swap that swaps two elements of a List<T>.

Sort a list of names by length, then alphabetically.

Get the names of the top 2 most expensive orders.

Return the uppercase name of customer 1 or "GUEST".

Append a line to log.txt, creating the file if needed.

Find the date 45 days after today.

Run two async lookups and combine their results with CompletableFuture.

Create a record Student(String name, int marks) that rejects marks above 100.

Which Maven command runs only the tests?

Insert a product with a PreparedStatement.

Add a test that an unknown coupon gives no discount.

Add GET /api/products/{id} that returns 404 when not found.