com.github.tomschi.commons.springdatajpa.dbo.AbstractJpaCompositeKey Maven / Gradle / Ivy
package com.github.tomschi.commons.springdatajpa.dbo;
import java.io.Serializable;
/**
* The {@link AbstractJpaCompositeKey} can be used as base class for
* JPA IdClass. Equals and hash code method is already implemented.
*
* @param The type of the first id.
* @param The type of the second id.
*
* @author Tomschi
* @since 0.1.2
*/
public abstract class AbstractJpaCompositeKey implements Serializable {
private static final long serialVersionUID = 1L;
/**
* Returns the first id.
* @return The id of type {@link T}
*/
protected abstract T getFirstId();
/**
* Returns the second id.
* @return The id of type {@link S}
*/
protected abstract S getSecondId();
/**
* Indicates if this object is equals to another object.
* For checking this equality the first id and the second
* id is used. Two objects are equal, if the given object
* is this object (this == obj) or the given
* object has the same class like this and both id's are equal.
*
* @param obj The reference object with which to compare.
* @return True, if obj equals this, else false.
*/
@Override
public boolean equals(Object obj) {
return this == obj
|| this.getClass() == obj.getClass()
&& getFirstId().equals(((AbstractJpaCompositeKey) obj).getFirstId())
&& getSecondId().equals(((AbstractJpaCompositeKey) obj).getSecondId());
}
/**
* Returns a hash code value for the object. The value
* is generated with the hashcode of the class name and
* the hashcode of the id's.
*
* @return A hash code value for the object.
*/
@Override
public int hashCode() {
return (this.getClass().getName().hashCode() * 13) + getFirstId().hashCode() + getSecondId().hashCode();
}
}