在JAVA中， 以下程序的运行结果是(     )

class Person {
    public Person() {
        System.out.println("this is a Person");
    }
}
public class Teacher extends Person {
    private String name = "tom";
    public Teacher() {
        System.out.println("this is a teacher");
        super();
    }
    public static void main(String[] args) {
        Teacher teacher = new Teacher();
        System.out.println(this.name);
    }
}