63. shape.computeVolume();
64. System.out.println("circle area: " + shape.getArea());
65. System.out.println("circle volume: " + shape.getVolume());
66. //多态调用
67. shape = sphere;
68. shape.computeArea();
69. shape.computeVolume();
70. System.out.println("Sphere area: " + shape.getArea());
71. System.out.println("Sphere volume: " + shape.getVolume());
72. }
73. }
这里对Circle对象多态调用computeVolume()毫无意义，仅是为了演示目的。其运行结果为：
74. circle area: 529.2967869138698
75. circle volume: 0.0
76. Sphere area: 2050.8395382450512
77. Sphere volume: 69865.26693621474
如果需要多态调用大量对象，可以使用数组和循环如下：
78. ...
79. for(int i = 0; i < objNum; i++) { //循环objNum次
80. shape[i].computeArea(); //i从0到objNum-1
81. shape[i].computeVolume();
82. System.out.println("The area: " + shape[i].getArea());
83. System.out.println("The volume: " + shape[i].getVolume());
84. }
这个循环语句也被称为多态管理循环。