Java의 추상 클래스

/* File name : Employee.java */
public abstract class Employee {
   private String name; private String address; private int number;
   public Employee(String name, String address, int number) {
      System.out.println("Constructing an Employee");
      this.name = name; this.address = address;
      this.number = number;
   }
   public double computePay() {
      System.out.println("Inside Employee computePay"); return 0.0;
   }
   public void mailCheck() {
      System.out.println("Mailing a check to " + this.name + " " + this.address);
   }
   public String toString() {
      return name + " " + address + " " + number;
   }
   public String getName() {
      return name;
   }
   public String getAddress() {
      return address;
   }
   public void setAddress(String newAddress) {
      address = newAddress;
   }
   public int getNumber() {
      return number;
   }
}

/* File name : AbstractDemo.java */
public class AbstractDemo {
   public static void main(String [] args) {
      /* Following is not allowed and would raise error */
      Employee e = new Employee("George W.", "Houston, TX", 43);
      System.out.println("\n Call mailCheck using Employee reference--");
      e.mailCheck();
    }
 }

Employee.java:46: Employee is abstract; cannot be instantiated
Employee e = new Employee("George W.", "Houston, TX", 43); ^ 1 error