Java 具有用于构建实体的内部类的实体

我正在JPA中尝试一对一映射， 这里我采取了学生和联系人的关系，每个学生都有一个联系人

我已经创建了学生实体，如下所示

@Entity
@Table(name="TBL_STUDENT")
public class Student  implements  Serializable{

   public Student(){ }
   @Id
   @GeneratedValue(strategy=GenerationType.IDENTITY)
   @Column(name="ID")  
   private Integer studentId;

   @OneToOne(targetEntity=StudentContact.class,fetch=FetchType.LAZY)
   @JoinColumn(name="CONTACT_ID")
   private StudentContact contact;
   ....
   ....
   ....
}

@Entity
@Table(name="TBL_STD_CONTACT")
public class StudentContact extends Serializable{
     public StudentContact(){ }

     @Id
     @Column(name="ID")
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Integer contactId;
     ...
     ...
     // all the properties mapped,

     public static class Builder{
         private Integer contactId;
         private String phoneNo;
         private String streetAddr;
         ....
         // all the properties as same as StudentContact

         public Builder(String val){
            this.city = val;
         }

         public Builder setContactId(Integer contactId) {
            this.contactId = contactId;
            return this;
         }

         // rest all the setter methods are like the above, having return type Builder

         public StudentContact build(){
              return new StudentContact(this);
         }
     }

     private StudentContact(Builder builder){
            this.contactId = builder.contactId;
            this.city = builder.city;
            this.phoneNo = builder.phoneNo;
            .......
            ...
     }
}

public class StudentTest {
    public static void main(String [] args){
        try{
             StudentDAO dao = new StudentDAO();
             Student student = dao.getEntity(110);  
             StudentContact contact = new StudentContact.Builder("Bhubaneshwar")
                                      .setPhoneNo("9867342313")
                                      .setPinCode("400392")
                                      .setState("Odhisha").build(); 

             student.setContact(contact);
             dao.updateEntity(student);
           }catch(Exception e){
               e.printStackTrace();
           }
}

现在，StudentContact实体如下所示

@Entity
@Table(name="TBL_STUDENT")
public class Student  implements  Serializable{

   public Student(){ }
   @Id
   @GeneratedValue(strategy=GenerationType.IDENTITY)
   @Column(name="ID")  
   private Integer studentId;

   @OneToOne(targetEntity=StudentContact.class,fetch=FetchType.LAZY)
   @JoinColumn(name="CONTACT_ID")
   private StudentContact contact;
   ....
   ....
   ....
}

@Entity
@Table(name="TBL_STD_CONTACT")
public class StudentContact extends Serializable{
     public StudentContact(){ }

     @Id
     @Column(name="ID")
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Integer contactId;
     ...
     ...
     // all the properties mapped,

     public static class Builder{
         private Integer contactId;
         private String phoneNo;
         private String streetAddr;
         ....
         // all the properties as same as StudentContact

         public Builder(String val){
            this.city = val;
         }

         public Builder setContactId(Integer contactId) {
            this.contactId = contactId;
            return this;
         }

         // rest all the setter methods are like the above, having return type Builder

         public StudentContact build(){
              return new StudentContact(this);
         }
     }

     private StudentContact(Builder builder){
            this.contactId = builder.contactId;
            this.city = builder.city;
            this.phoneNo = builder.phoneNo;
            .......
            ...
     }
}

public class StudentTest {
    public static void main(String [] args){
        try{
             StudentDAO dao = new StudentDAO();
             Student student = dao.getEntity(110);  
             StudentContact contact = new StudentContact.Builder("Bhubaneshwar")
                                      .setPhoneNo("9867342313")
                                      .setPinCode("400392")
                                      .setState("Odhisha").build(); 

             student.setContact(contact);
             dao.updateEntity(student);
           }catch(Exception e){
               e.printStackTrace();
           }
}

在上面的StudentContact实体中，您可以看到我创建了一个内部类生成器，其职责是通过使用其“build”方法构建StudentContact对象，您可以在下面提到的StudentTest类中看到

现在我写了一个StudentTest类，主要方法如下：

@Entity
@Table(name="TBL_STUDENT")
public class Student  implements  Serializable{

   public Student(){ }
   @Id
   @GeneratedValue(strategy=GenerationType.IDENTITY)
   @Column(name="ID")  
   private Integer studentId;

   @OneToOne(targetEntity=StudentContact.class,fetch=FetchType.LAZY)
   @JoinColumn(name="CONTACT_ID")
   private StudentContact contact;
   ....
   ....
   ....
}

@Entity
@Table(name="TBL_STD_CONTACT")
public class StudentContact extends Serializable{
     public StudentContact(){ }

     @Id
     @Column(name="ID")
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Integer contactId;
     ...
     ...
     // all the properties mapped,

     public static class Builder{
         private Integer contactId;
         private String phoneNo;
         private String streetAddr;
         ....
         // all the properties as same as StudentContact

         public Builder(String val){
            this.city = val;
         }

         public Builder setContactId(Integer contactId) {
            this.contactId = contactId;
            return this;
         }

         // rest all the setter methods are like the above, having return type Builder

         public StudentContact build(){
              return new StudentContact(this);
         }
     }

     private StudentContact(Builder builder){
            this.contactId = builder.contactId;
            this.city = builder.city;
            this.phoneNo = builder.phoneNo;
            .......
            ...
     }
}

public class StudentTest {
    public static void main(String [] args){
        try{
             StudentDAO dao = new StudentDAO();
             Student student = dao.getEntity(110);  
             StudentContact contact = new StudentContact.Builder("Bhubaneshwar")
                                      .setPhoneNo("9867342313")
                                      .setPinCode("400392")
                                      .setState("Odhisha").build(); 

             student.setContact(contact);
             dao.updateEntity(student);
           }catch(Exception e){
               e.printStackTrace();
           }
}

当我从netbeans IDE运行StudentTest时，它给出了一个错误

Exception in thread "main" java.lang.VerifyError: Constructor must call super() or this() before return in method com.entities.StudentContact.<init>()V at offset 0

线程“main”java.lang.VerifyError中出现异常：构造函数必须调用super（）或this（），然后才能在方法com.entities.StudentContact中返回。（）V偏移量0

我无法理解这个错误，这个错误是否是因为我在StudentContact类中创建的内部类

---

如何解决这个问题，java.lang.VerifyError意味着字节码不正确。通常可以通过项目的全面清理/重建来修复。（我有时在包/类重命名或类从一个包移动到另一个包后看到它）

---

正如注释中提到的：

extends Serializable

不正确。（可能是您字节码问题的原因？

即使我在StudentContact的私有构造函数中编写了super（）或this（），它仍然会给出一个错误，您还有其他问题；StudentContact extends Serializable就是其中之一