The following java for-loop exercises have been collected from various internet sources such as programmr.com and codewars. Go to my tutoring page if you need more help and would like to talk to a tutor.
User input does not work with the embedded compiler (paiza) below. That is why you see the problems being worded and setup slightly differently than on the rest of the page.
Happy Coding!
Exercise 1:
Determine and print the number of times the character ‘a’ appears in the input entered by the user.
Program Starts:
Enter String:
This is a test Output:
Output:
Number of a's: 1
Exercise 2:
Write a program that will print a box of #’s taking from user the height and width values.
Program Starts:
Enter height:
7
Enter width:
5
Output:
#####
#####
#####
#####
#####
#####
#####
Exercise 3
Write a program to find the sum of 5 integers.
Program Starts:
Enter an integer:
2
Enter an integer:
4
Enter an integer:
3
Enter an integer:
-2
Enter an integer:
3
Output:
Total is: 15
Exercise 4
Write a java program to calculate the factorial value of given number. Factorial x –> x * x-1 * x-2…x*1
Example: factorial 4 = 4 * 3 * 2 * 1 = 24
Program Starts:
Enter a number:
5
Output:
Factorial of the number is: 120
Exercise 5
Suppose we have a database composed of two fields or columns (arrays), the first field is for the username (user[]) and the other one is for the password(pass[]) .
This is how it looks like:
user[0] = “Hassan” ;
user[1] =”Idris”;
user[2]=”Trevor” ;
And their passwords correspond with their indexes.
pass[0] = “homecomingking”;
pass[1] = “turnupcharlie”;
pass[2] = “afraidofthedark”;
Then if one of them had successfully login, the output should be:
Enter username: Hassan
Enter password: homecomingking
Hello Hassan!
But if not, “Incorrect Login!”
You can ignore case for the username but not for the password.
Program Starts:
Enter username:
Becky
Enter password:
123
Output:
Hello Becky!
Exercise 6
You have to design the code such that the user has only three tries to guess the correct pin of the account. You set the pin as a constant with a final attribute. When correct display “Correct, welcome back.” When incorrect display “Incorrect, try again.”. When ran out of tries display “Sorry but you have been locked out.”
Program Starts:
Please enter pin:
22132
Output:
Incorrect, try again.
Please enter pin:
23412
Output:
Incorrect, try again.
Please enter pin:
12345
Output:
Correct, welcome back.
Program Starts:
Please enter pin:
22132
Output:
Incorrect, try again.
Please enter pin:
23412
Output:
Incorrect, try again.
Please enter pin:
00000
Output:
Sorry but you have been locked out.
Exercise 7
Write a program that prompts user for a word and prints “Yes” if it is a palindrome and “No” if it is not.
Program Starts:
Enter a string:
mom
Output:
Yes
Exercise 8 (Advanced)
This is a code wars kata. click here to train on “Abbreviate a Two Word Name” on code wars.
Write a function to convert a name into initials. You can assume the program takes in two words with one space in between them.
The output should be two capital letters with a dot separating them.
It should look like this:
Program Starts:
Please enter name:
Sam Smith
Output:
S.S
Exercise 9
This is a code wars kata. click here to train on “Grasshopper – Summation” on code wars.
Write a program that finds the summation of every number from 1 to num. The number will always be a positive integer greater than 0.
Program Starts:
Please enter number
2
Output:
1 + 2 = 3
Program Starts:
Please enter number
8
Output:
1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 = 36
Exercise 10
This is a code wars kata. click here to train on “Sentence Smash” on code wars.
Write a method smash that takes an array of words and smashes them together into a sentence and returns the sentence. You can ignore any need to sanitize words or add punctuation, but you should add spaces between each word. Be careful, there shouldn’t be a space at the beginning or the end of the sentence!
var words = ['hello', 'world', 'this', 'is', 'great']; smash(words); // returns "hello world this is great"
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