package address;import java.io.*;public class AddressesPK implements Serializable {  public String firstName;  public String lastName;  public AddressesPK() {  }	//設置復合鍵  public AddressesPK(String firstName, String lastName) {    this.firstName = firstName;    this.lastName = lastName;  }  //用于匹配對象  public boolean equals(Object obj) {    if (this.getClass().equals(obj.getClass())) {      AddressesPK that = (AddressesPK) obj;      return this.firstName.equals(that.firstName) && this.lastName.equals(that.lastName);    }    return false;  }  public int hashCode() {    return (firstName + lastName).hashCode();  }}