Conditional Execution - Building Java Programs: A Back to Basics Approach - page 296

26. Consider the following Java method, which is written incorrectly:

// This method should return how many of its three
// arguments are odd numbers.
public static void printNumOdd(int n1, int n2, int n3) {
int count = 0;
if (n1 % 2 != 0) {
count++;
} else if (n2 % 2 != 0) {
count++;
} else if (n3 % 2 != 0) {
count++;

}
System.out.println(count + " of the 3 numbers are odd.");

}

Under what cases will the method print the correct answer, and when will it print an incorrect answer? What should
be changed to fix the code? Can you think of a way to write the code correctly without any if/else statements?

Exercises

1. Write a method called fractionSum that accepts an integer parameter n and returns as a double the sum of the
first n terms of the sequence

n

1
i

a

i = 1

In other words, the method should generate the following sequence:

1
2 +

1
3 +

1
4 +

1
5 + Á

1 +

You may assume that the parameter n is nonnegative .

2. Write a method called repl that accepts a String and a number of repetitions as parameters and returns the
String concatenated that many times. For example, the call repl("hello", 3) should return
"hellohellohello" . If the number of repetitions is zero or less, the method should return an empty string.
3. Write a method called season that takes as parameters two integers representing a month and day and returns a
String indicating the season for that month and day. Assume that the month is specified as an integer between 1
and 12 (1 for January, 2 for February, and so on) and that the day of the month is a number between 1 and 31. If the
date falls between 12/16 and 3/15, the method should return "winter" . If the date falls between 3/16 and 6/15, the
method should return "spring" . If the date falls between 6/16 and 9/15, the method should return "summer" . And
if the date falls between 9/16 and 12/15, the method should return "fall" .
4. Write a method called pow that accepts a base and an exponent as parameters and returns the base raised to the given
power. For example, the call pow(3, 4) should return 3 * 3 * 3 * 3 , or 81 . Assume that the base and exponent
are nonnegative.