Introduction to Java Programming Exercises

1. Hands-on Exercises
Java 101: Introduction to Java

2. Hands-on Exercise
Basic Java Program

3. Create Basic Java Program
• Create the following program by typing it into
a text editor, and save it as HelloWorld.java.

4. Compile Basic Java Program
• Compile it by typing at the command-line: javac
HelloWorld.java.
• This creates a Java bytecode file named:
HelloWorld.class.

5. Execute Basic Java Program
• Execute it by typing at the command-line: java
HelloWorld.

6. Hands on Exercise
Command Line Arguments

7. Command Line Arguments
• Create a program that takes a name as command-line argument and
prints “Hi <name>, How are you?”

8. Hands-on Exercise
Integer Operations

9. Exercise: Integer Operations
• Create new Java project in Eclipse called IntegerOperations
• Create a Java class named IntOps that performs integer operations on a pair of integers
from the command line and prints the results.

10. Solution: Integer Operations

11. Hands-on Exercise
Leap Year Finder

12. Exercise: Leap Year Finder
• A year is a leap year if it is either divisible by 400 or
divisible by 4 but not 100.
• Create a java project in Eclipse named LeapYearFinder
• Write a java class named LeapYear that takes a year as
command line argument and prints true if it’s a leap
year and false if not

13. Solution: Leap Year Finder

14. Hands-on Exercise
Powers of Two

15. Exercise: Powers of Two
• Create a new Java project in Eclipse named Pow2
• Write a java class named PowerOfTwo to print powers of 2 that are
<= 2N where N is a number passed as an argument to the program.
– Increment i from 0 to N.
– Double v each time

16. Solution: Power of 2

17. Bonus Exercises
Java 101: Introduction to Java

18. Hands-on Exercise
Random Number Generator

19. Exercise: Random Number Generator
• Create a new java project in Eclipse called RandomInteger
• Write a java class named RandomInt to generate a pseudo-random
number between 0 and N-1 where N is a number passed as an
argument to the program

20. Solution: Random Number Generator

21. Hands-on Exercise
Array of Days

22. Exercise: Array of Days
• Create a new Java project in Eclipse named ArrayOfDays
• Create a java class named DayPrinter that prints out
names of the days in a week from an array using a for-
loop.

23. Solution: Arrays of Days
public class DayPrinter {
public static void main(String[] args) {
//initialize the array with the names of days of the
week
String[] daysOfTheWeek =
{"Sunday","Monday","Tuesday","Wednesday",
"Thuesday","Friday”,"Saturday"};
//loop through the array and print their elements to
//stdout
for (int i= 0;i < daysOfTheWeek.length;i++ ){
System.out.println(daysOfTheWeek[i]);
}
}
}
% javac DayPrinter.java
% java DayPrinter
Sunday
Monday
Tuesday
Wednesday
Thuesday
Friday
Saturday

24. Hands-on Exercise
Print Personal Details

25. Exercise: Print Personal Details
• Write a program that will print your name and
address in the Console view of Eclipse, for
example:
Alex Johnson
23 Main Street
New York, NY 10001 USA

26. Hands-on Exercise
Sales Discount

27. Exercise: Sales Discount
• Create a new project in Eclipse named Sale
• Create, compile, and run the FriendsAndFamily class as illustrated below
• Debug this program in your IDE to find out how it works