Object-Oriented Programming with Java, part I + II

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Authors: Arto Hellas, Matti Luukkainen
Translators to English: Emilia Hjelm, Alex H. Virtanen, Matti Luukkainen, Virpi Sumu, Birunthan Mohanathas, Etiënne Goossens
Extra material added by: Etiënne Goossens, Maurice Snoeren, Johan Talboom
Adapted for Informatica by: Ruud Hermans

The course is maintained by Technische Informatica Breda

For loops

By now you will have noticed that there are usually 3 important components in a loop; the initialization, condition and increment

int i = 0;              //initialization
while(i < 10) {         //condition
    System.out.println(i);
    i++;                //increment
}

These 3 parts are key to a successful loop, and for instance, forgetting the increment will result in an infinite loop. They are split up on 3 different lines, which is not good for the structure of your code. To improve the structure, java offers a for-loop. This for-loop combines these 3 parts in a single line

for(int i = 0; i < 10; i++) {
    System.out.println(i);
}

This program is identical to the while loop. The for has all 3 different components between brackets, and is therefore different than the while() or if() conditions. This for-syntax is very powerful, but can some time getting used to. For now, you can pick if you do loops with a while() statement or a for() statement

Exercise for-loop-1 Checkerboard

Write a program, using for-loops, that draws a checkerboard Note that you will be using 2 for-loops here, one to iterate over the rows, and one that iterates over the columns. Note that you use # for the black tiles, and the first, topleft tile should be a #

Expected output:

# # # # # 
 # # # # #
# # # # # 
 # # # # #
# # # # # 
 # # # # #
# # # # # 
 # # # # #
# # # # # 
 # # # # #