Program Logic and Indefinite Loops - Building Java Programs: A Back to Basics Approach - page 356

The following sample log of execution demonstrates the new input robustness of
this program:

Try to guess my two-digit
number, and I'll tell you how
many digits from your guess
appear in my number.

Your guess? 12
Incorrect (hint: 0 digits match)
Your guess? okay
Not an integer; try again.
Your guess? 34
Incorrect (hint: 1 digits match)
Your guess? 35
Incorrect (hint: 1 digits match)
Your guess? 67
Incorrect (hint: 0 digits match)
Your guess? 89
Incorrect (hint: 0 digits match)
Your guess? 3
Incorrect (hint: 2 digits match)
Your guess? 300
Out of range; try again.
Your guess? 30
You got it right in 7 tries.

Notice that we're careful to comment our code to document relevant preconditions
and postconditions of our methods. The precondition of the matches method is that
the two parameters are unique two-digit numbers. The postcondition of our new
getGuesses method is that it returns a guess between 0 and 99 inclusive. Also, note
that the program does not count invalid input ( okay and 300 in the previous sample
log of execution) as guesses.

Chapter Summary

Java has a while loop in addition to its for loop. The
while loop can be used to write indefinite loops that keep
executing until some condition fails.

Java can generate pseudorandom numbers using objects of
the Random class.

The do/while loop is a variation on the while loop that
performs its loop test at the end of the loop body. A
do/while loop is guaranteed to execute its body at least
once.

Priming a loop means setting the values of variables that
will be used in the loop test, so that the test will be sure to
succeed the first time and the loop will execute.