ARRAYS - Java Programming: From Problem Analysis to Program Design - page 585

3. If a method has both a variable length formal parameter and other types
of formal parameters, then the variable length formal parameter must be
the last formal parameter of the formal parameter list.
Before giving more examples of methods with a variable length formal parameter list, we
note the following.
One way to process the elements of an array one-by-one, starting at the first element, is
to use an index variable, initialized to 0 , and a loop. For example, to process the elements
of an array, list , you can use a for loop, such as the following:

for ( int index; index < list.length; index++)
//process list[index]

In fact, this chapter uses these types of loops to process the elements of an array. The most
recent version of Java provides a special type of for loop to process the elements of an object,
such as an array. The syntax to use this for loop to process the elements of an array is:

for (dataType identifier : arrayName)
statements

where identifier is a variable and the data type of identifier is the same as the data
type of the array elements. This form of the for loop is called a foreach loop.
For example, suppose list is an array and each element is of type double , and sum is a
double variable. The following code finds the sum of the elements of list :

9

sum = 0; //Line 1

for ( double num : list) //Line 2

sum = sum + num; //Line 3

The for statement in Line 2 is read for each num in list . The identifier num is initialized
to list[0] . In the next iteration, the value of num is list[1] , and so on.
Using the foreach loop, the for loop in the method largest , in Example 9-10, can be
written as:
for ( double num : list)
{

if (max < num)
max = num;

}

(The modified program, named LargestNumberVersionII.java , that uses the foreach
loop to determine the largest element in list , can be found with the Additional Student
Files at www.cengagebrain.com.)
Example 9-11 shows that the variable length formal parameters (list) of a method can be
objects. This example uses the class Clock designed in Chapter 8.