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Author Message
 Post subject: Generating equals and hashCode with Hibernate tools
PostPosted: Thu Jul 21, 2005 11:18 am 
Newbie

Joined: Tue Jul 19, 2005 6:39 am
Posts: 4
Location: Venice, Italy
Hibernate version: 3.0.5

Hibernate tools version: Eclipse plugin 3.0.0 alpha4

Hi,
I generate the equals and hashCode methods using the meta-syntax on this hbm file:


Code:
<?xml version="1.0" encoding="ASCII"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping auto-import="true" default-access="property" default-cascade="none" default-lazy="true" package="com.foo.bar.test.equals">
  <class abstract="false" dynamic-insert="false" dynamic-update="false" mutable="true" name="TestEquals" optimistic-lock="version" polymorphism="implicit" select-before-update="false" table="testEquals">
    <meta attribute="implement-equals" inherit="true">true</meta>
    <id column="id" name="id" type="long">
      <meta attribute="use-in-equals" inherit="true">true</meta>
      <generator class="native"/>
    </id>
    <property column="text1" name="text1" type="string"/>
    <property column="text2" name="text2" type="string"/>
    <property column="text3" name="text3" type="string"/>
  </class>
</hibernate-mapping>


obtaining this generated class:

Code:
/**
* TestEquals generated by hbm2java
*/
public class TestEquals  implements java.io.Serializable {

    // Fields   

     private Long id;
     private String text1;
     private String text2;
     private String text3;


    // Constructors

    /** default constructor */
    public TestEquals() {
    }
   
    /** constructor with id */
    public TestEquals(Long id) {
        this.id = id;
    }
   
   
   

    // Property accessors

    /**
     *
     */
    public Long getId() {
        return this.id;
    }
   
    public void setId(Long id) {
        this.id = id;
    }

    /**
     *
     */
    public String getText1() {
        return this.text1;
    }
   
    public void setText1(String text1) {
        this.text1 = text1;
    }

    /**
     *
     */
    public String getText2() {
        return this.text2;
    }
   
    public void setText2(String text2) {
        this.text2 = text2;
    }

    /**
     *
     */
    public String getText3() {
        return this.text3;
    }
   
    public void setText3(String text3) {
        this.text3 = text3;
    }

   public boolean equals(Object other) {
         if ( (this == other ) ) return true;
       if ( (other == null ) ) return false;
       if ( !(other instanceof TestEquals) ) return false;
       TestEquals castOther = ( TestEquals ) other;
         
       return (this.getId()==castOther.getId()) || ( this.getId()!=null && castOther.getId()!=null && this.getId().equals(castOther.getId()) );
   }
   
   public int hashCode() {
         int result = 17;
         
         result = 37 * result + this.getId().hashCode();
         ;
         ;
         ;
         return result;
   }   


}


In the generated code for the method hashCode() there is a list of ";" as long as the number of properties of the class not included in the clause "use-in-equals". This is only a bit ridiculous to see, but should be fixed.

My concern is: is it possible to get a NullPointerException in the method hashCode()? What if I issue a new TestEquals()? In this case getId() should return null. Have I to define an explicit unsaved-value clause in the id mapping with a not null value?

Thanks
Adriano


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