> For the complete documentation index, see [llms.txt](https://codewithmeiy.gitbook.io/core-java/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://codewithmeiy.gitbook.io/core-java/test-your-knowledge/input-output.md).

# Input / Output

Here are 20 problem statements that test your knowledge of console input/output in Java:

1. **Print Message**: Write a Java program to print "Hello, World!" to the console.
2. **Read Integer**: Prompt the user to enter an integer and then print it back to the console.
3. **Read Double**: Prompt the user to enter a double value and then print it back to the console.
4. **Read String**: Prompt the user to enter their name and then print a greeting message with their name.
5. **Read Multiple Integers**: Prompt the user to enter three integers separated by spaces and then print their sum.
6. **Read Multiple Doubles**: Prompt the user to enter three double values separated by commas and then print their average.
7. **Read Character**: Prompt the user to enter a single character and then print it back to the console.
8. **Read Line**: Prompt the user to enter a sentence and then print the sentence in uppercase letters.
9. **Read Boolean**: Prompt the user to enter a boolean value (true/false) and then print it back to the console.
10. **Read Array**: Prompt the user to enter five integers separated by spaces and then print the array in reverse order.
11. **Read Matrix**: Prompt the user to enter elements of a 3x3 matrix and then print the matrix.
12. **Read Password**: Prompt the user to enter a password (without displaying it) and then print "Access Granted" if the password is correct.
13. **Read File Path**: Prompt the user to enter a file path and then print the name of the file.
14. **Read Age**: Prompt the user to enter their age and then print "You are a minor" if the age is less than 18, otherwise print "You are an adult".
15. **Read Name and Age**: Prompt the user to enter their name and age, then print a message with their name and whether they are a minor or an adult.
16. **Read Multiple Strings**: Prompt the user to enter three words separated by commas and then print them in alphabetical order.
17. **Read Two Numbers**: Prompt the user to enter two numbers separated by a space, then print their sum, difference, product, and quotient.
18. **Read Decimal Number**: Prompt the user to enter a decimal number and then print its square root.
19. **Read Date**: Prompt the user to enter a date in the format "DD/MM/YYYY" and then print it in the format "Month DD, YYYY".
20. **Read Color**: Prompt the user to enter a color (red, green, blue) and then print a message based on the color (e.g., "You chose red").
21. **Basic Input/Output**: Prompt the user to enter their name and age, then print a greeting message with their name and age.
22. **Read and Display Array**: Prompt the user to enter five numbers separated by spaces, store them in an array, and then print the array.
23. **Calculate Area**: Prompt the user to enter the radius of a circle, calculate the area, and print the result.
24. **User Authentication**: Ask the user to enter a username and password. If the username is "admin" and the password is "password123", print "Access granted"; otherwise, print "Access denied".
25. **Calculate Discount**: Prompt the user to enter the price of an item and the discount percentage. Calculate the discounted price and print it.
26. **Temperature Conversion**: Prompt the user to enter a temperature in Celsius, convert it to Fahrenheit, and print the result.
27. **String Manipulation**: Prompt the user to enter a string, convert it to uppercase, and print the result.
28. **Calculate GPA**: Prompt the user to enter grades for three subjects, calculate the GPA, and print it.
29. **Find Maximum and Minimum**: Prompt the user to enter five numbers separated by spaces, find and print the maximum and minimum numbers.
30. **Check Prime Number**: Prompt the user to enter a number, check if it's prime, and print "Prime" or "Not Prime" accordingly.
31. **Reverse String**: Prompt the user to enter a string, reverse it, and print the result.
32. **Shopping Cart**: Implement a simple shopping cart where the user can enter the name and price of items until they enter "done". Print the total cost.
33. **Count Characters**: Prompt the user to enter a sentence, count the number of characters (excluding spaces), and print the count.
34. **Generate Multiplication Table**: Prompt the user to enter a number, generate its multiplication table from 1 to 10, and print it.
35. **Factorial Calculation**: Prompt the user to enter a number, calculate its factorial, and print the result.
36. **Check Palindrome**: Prompt the user to enter a word, check if it's a palindrome, and print "Palindrome" or "Not Palindrome" accordingly.
37. **Sorting Array**: Prompt the user to enter five numbers separated by spaces, sort them in ascending order, and print the sorted array.
38. **Binary to Decimal Conversion**: Prompt the user to enter a binary number, convert it to decimal, and print the result.
39. **Word Count**: Prompt the user to enter a paragraph, count the number of words, and print the count.
40. **Create Calendar**: Prompt the user to enter a month and year, then print the calendar for that month.

These problem statements cover a wide range of scenarios, from simple input/output tasks to more complex calculations and manipulations.