Conditionals and Loops - Java Software Solutions: Foundations of Program Design - page 231

The following loop prints the values from 1 to 5. Each iteration
through the loop prints one value, then increments the counter.

KEY CONCEPT
A while statement executes the
same statement until its condition
becomes false.

int count = 1;
while (count <= 5)
{
System.out.println (count);
count++;
}

Note that the body of the while loop is a block containing two statements. The
entire block is repeated on each iteration of the loop.
Let's look at another program that uses a while loop. The Average program
shown in Listing 5.7 reads a series of integer values from the user, sums them up,
and computes their average.
We don't know how many values the user may enter, so we need to have a way
to indicate that the user has finished entering numbers. In this program, we desig-
nate zero to be a sentinel value that indicates the end of the input. The while loop
continues to process input values until the user enters zero. This assumes that zero

LISTING 5.7

//********************************************************************
// Average.java Author: Lewis/Loftus
//
// Demonstrates the use of a while loop, a sentinel value, and a
// running sum.
//********************************************************************

import java.text.DecimalFormat;
import java.util.Scanner;

public class Average
{
//-----------------------------------------------------------------
// Computes the average of a set of values entered by the user.
// The running sum is printed as the numbers are entered.
//-----------------------------------------------------------------
public static void main (String[] args)
{
int sum = 0, value, count = 0;
double average;

Scanner scan = new Scanner (System.in);