Java Reference
In-Depth Information
circleArray
circleArray[0]
Circle object 0
reference
circleArray[1]
Circle object 1
circleArray[9]
Circle object 9
F IGURE 9.19
In an array of objects, an element of the array contains a reference to an
object.
Listing 9.11 gives an example that demonstrates how to use an array of objects. The pro-
gram summarizes the areas of an array of circles. The program creates circleArray , an
array composed of five Circle objects; it then initializes circle radii with random values and
displays the total area of the circles in the array.
L ISTING 9.11
TotalArea.java
1 public class TotalArea {
2 /** Main method */
3 public static void main(String[] args) {
4 // Declare circleArray
5 CircleWithPrivateDataFields[] circleArray;
6
7 // Create circleArray
8 circleArray = createCircleArray();
9
10
array of objects
// Print circleArray and total areas of the circles
11
printCircleArray(circleArray);
12 }
13
14 /** Create an array of Circle objects */
15 public static CircleWithPrivateDataFields[] createCircleArray() {
16 CircleWithPrivateDataFields[] circleArray =
17 new CircleWithPrivateDataFields[ 5 ];
18
19 for ( int i = 0 ; i < circleArray.length; i++) {
20 circleArray[i] =
21
new CircleWithPrivateDataFields(Math.random() * 100 );
22 }
23
24
// Return Circle array
25
return circleArray;
return array of objects
26 }
27
28 /** Print an array of circles and their total area */
29 public static void printCircleArray(
30 CircleWithPrivateDataFields[] circleArray) {
31 System.out.printf( "%-30s%-15s\n" , "Radius" , "Area" );
32 for ( int i = 0 ; i < circleArray.length; i++) {
33 System.out.printf( "%-30f%-15f\n" , circleArray[i].getRadius(),
34 circleArray[i].getArea());
35 }
36
37 System.out.println( "—————————————————————————————————————————-" );
38
39 // Compute and display the result
40 System.out.printf( "%-30s%-15f\n" , "The total area of circles is" ,
41
pass array of objects
sum(circleArray) );
42 }
 
 
Search WWH ::




Custom Search