Java 静态变量，用于维护内存中Employee对象数量的计数
静态变量，用于维护内存中Employee对象数量的计数
实例源码：
源代码：
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public class Main /**from NowJava.com - 时 代 Java**/3
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{5
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public static void main(String[] args)7
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{9
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// show that count is 0 before creating Employees11
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System.out.printf("Employees before instantiation: %d%n",13
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Employee.getCount());15
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// create two Employees; count should be 218
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Employee e1 = new Employee("Ana", "Bates");20
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Employee e2 = new Employee("Mary", "Lady");22
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// show that count is 2 after creating two Employees26
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System.out.printf("%nEmployees after instantiation:%n");28
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System.out.printf("via e1.getCount(): %d%n", e1.getCount());30
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System.out.printf("via e2.getCount(): %d%n", e2.getCount());32
/**33
n o w j a v a . c o m34
**/35
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System.out.printf("via Employee.getCount(): %d%n", 37
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Employee.getCount());39
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// get names of Employees43
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System.out.printf("%nEmployee 1: %s %s%nEmployee 2: %s %s%n",45
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e1.getFirstName(), e1.getLastName(), 47
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e2.getFirstName(), e2.getLastName());49
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} 51
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}53
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class Employee 56
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{58
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private static int count = 0; // number of Employees created60
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private String firstName;62
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private String lastName;64
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// initialize Employee, add 1 to static count and 67
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// output String indicating that constructor was called69
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public Employee(String firstName, String lastName)71
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{73
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this.firstName = firstName;75
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this.lastName = lastName;77
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++count; // increment static count of employees80
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System.out.printf("Employee constructor: %s %s; count = %d%n",82
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firstName, lastName, count);84
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} 86
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// get first name89
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