could not get a field value by reflection getter and query to sum multiple columns in pure Hibernate
<p>I have written this query but getting problem with this query.
and i want to write that query in Hibernate.</p>

<pre><code>Query getActivoCrtTotalquery = (Query) session
                .createQuery("select sum(a.servicios_por_pagares)+sum(a.producto_en_processo)+sum(a.materia_prima)+sum(a.moteriales)+sum(a.marcaderia_en_transito)+sum(a.mercaderia)+sum(a.productos_terminado) from Activocrt_Master a where a.dni=:dni" );

        getActivoCrtTotalquery.setParameter("dni", dni);
                List list = getActivoCrtTotalquery.list();
            result = (double) list.get(0);
            session.close();
</code></pre>

<p><strong>Exception</strong>: </p>

<blockquote>
  <p>org.hibernate.PropertyAccessException: could not get a field value by
  reflection getter of com.caja.creditprocess.hbmfiles.Doi_Master.dni
    at
  org.hibernate.property.DirectPropertyAccessor$DirectGetter.get(DirectPropertyAccessor.java:35)
    at
  org.hibernate.tuple.entity.AbstractEntityTuplizer.getIdentifier(AbstractEntityTuplizer.java:183)
    at
  org.hibernate.persister.entity.AbstractEntityPersister.getIdentifier(AbstractEntityPersister.java:3596)
    at
  org.hibernate.persister.entity.AbstractEntityPersister.isTransient(AbstractEntityPersister.java:3312)
    at org.hibernate.engine.ForeignKeys.isTransient(ForeignKeys.java:181)
    at
  org.hibernate.engine.ForeignKeys.getEntityIdentifierIfNotUnsaved(ForeignKeys.java:218)
    at org.hibernate.type.EntityType.getIdentifier(EntityType.java:397)
    at
  org.hibernate.type.ManyToOneType.nullSafeSet(ManyToOneType.java:87)
    at
  org.hibernate.param.NamedParameterSpecification.bind(NamedParameterSpecification.java:38)
    at
  org.hibernate.loader.hql.QueryLoader.bindParameterValues(QueryLoader.java:491)
    at
  org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1563)
    at org.hibernate.loader.Loader.doQuery(Loader.java:673)     at
  org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236)
    at org.hibernate.loader.Loader.doList(Loader.java:2213)     at
  org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2104)    at
  org.hibernate.loader.Loader.list(Loader.java:2099)    at
  org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:378)   at
  org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:338)
    at
  org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:172)
    at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1121)   at
  org.hibernate.impl.QueryImpl.list(QueryImpl.java:79)  at
  com.caja.creditprocess.daoimpl.EvaluationDAOImpl.getActivoCrtTotal(EvaluationDAOImpl.java:302)
    at
  com.caja.creditprocess.managerimpl.EvaluationManagerImpl.saveActivo(EvaluationManagerImpl.java:278)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)  at
  sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at
  sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)     at
  org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:302)
    at
  org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190)
    at
  org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
    at
  org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:110)
    at
  org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
    at
  org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:208)
    at com.sun.proxy.$Proxy28.saveActivo(Unknown Source)    at
  EvaluationTest.sendActivoDetails(EvaluationTest.java:150)     at
  sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)   at
  sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at
  sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)     at
  org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
    at
  org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at
  org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at
  org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at
  org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
    at
  org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83)
    at
  org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)
    at
  org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:231)
    at
  org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)  at
  org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)   at
  org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)     at
  org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)   at
  org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)  at
  org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at
  org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)    at
  org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:174)
    at
  org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at
  org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at
  org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at
  org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
    at
  org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at
  org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
  Caused by: java.lang.IllegalArgumentException: Can not set
  java.lang.String field com.caja.creditprocess.hbmfiles.Doi_Master.dni
  to java.lang.String   at
  sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:167)
    at
  sun.reflect.UnsafeFieldAccessorImpl.throwSetIllegalArgumentException(UnsafeFieldAccessorImpl.java:171)
    at
  sun.reflect.UnsafeFieldAccessorImpl.ensureObj(UnsafeFieldAccessorImpl.java:58)
    at
  sun.reflect.UnsafeObjectFieldAccessorImpl.get(UnsafeObjectFieldAccessorImpl.java:36)
    at java.lang.reflect.Field.get(Field.java:393)  at
  org.hibernate.property.DirectPropertyAccessor$DirectGetter.get(DirectPropertyAccessor.java:32)
    ... 62 more</p>
</blockquote>

<p><strong>My Entities are</strong></p>

<pre><code>  @Entity
@Table(name="Activocrt_Master")
public class Activocrt_Master implements Serializable{

    @Id
    @Column(name="activocrt_master_id")
    private String activocrt_master_id;

    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name="dni")
    private Doi_Master dni;


    @Column(name="servicios_por_pagares")
    private double servicios_por_pagares;

    @Column(name="producto_en_processo")
    private double producto_en_processo;

    @Column(name="materia_prima")
    private double materia_prima;

    @Column(name="moteriales")
    private double moteriales;

    @Column(name="marcaderia_en_transito")
    private double marcaderia_en_transito;

    @Column(name="mercaderia")
    private double mercaderia;

    @Column(name="productos_terminado")
    private double productos_terminado;

//setters and getters

}
</code></pre>

<p><strong>Doi_Master.java</strong></p>

<pre><code>@Entity
@Table(name="Doi_Master")
public class Doi_Master implements Serializable{

    @Id
    @Column(name="dni")
    private String dni;

//setters and getters
}
</code></pre>