// main.java
public class Main {
    public static void main(String[] args) {
       // TODO: 给Person类增加一个静态字段count和静态方法getCount，统计实例的个数       
       Person p1 = new Person("小明");       
       System.out.println(Person.getCount()); // 1       
       Person p2 = new Person("小红");       
       System.out.println(Person.getCount()); // 2       
       Person p3 = new Person("小军");       
       System.out.println(Person.getCount()); // 3    
    }
}

// Person.java
public class Person {
    String name;    
    private static int count;    
    public Person(String name) {
       this.name = name;       
       count+=1;    
    }
    public static int getCount() {
       return count;    
    }

}