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POCan't save an object to database using hibernate
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copied!<p>I am new to sturts2 and hibernate frameworks. I am making test web application. I have one model class 'UserDetails' one DAO class one Implementation of DAO and action class. And when saving object to database I'm getting the following error: </p> <p>UserDetails.class</p> <pre><code>package org.project.model; import javax.persistence.Column; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.Table; @Entity @Table(name="user_details") public class UserDetails { private int userId; private String userName; @Id @GeneratedValue @Column(name="id") public int getUserId() { return userId; } public void setUserId(int userId) { this.userId = userId; } @Column(name="name") public String getUserName() { return userName; } public void setUserName(String userName) { this.userName = userName; } } </code></pre> <p>UserDetailsDaoImpl - implementation class</p> <pre><code> package org.project.model.dao.iml; import java.util.List; import org.hibernate.Session; import org.hibernate.Transaction; import org.project.model.UserDetails; import org.project.model.dao.UserDetailsDao; import com.googlecode.s2hibernate.struts2.plugin.annotations.SessionTarget; import com.googlecode.s2hibernate.struts2.plugin.annotations.TransactionTarget; public class UserDetailsDaoImpl implements UserDetailsDao { @SessionTarget Session session; @TransactionTarget Transaction transaction; @Override public void saveUser(UserDetails user) { try { session.save(user); } catch (Exception e) { transaction.rollback(); e.printStackTrace(); } } @SuppressWarnings("unchecked") @Override public List<UserDetails> listUser() { List<UserDetails> users = null; try { users = session.createQuery("from UserDetails").list(); } catch (Exception e) { e.printStackTrace(); } return users; } } </code></pre> <p>Action class is</p> <pre><code>package org.project.actions; import java.util.ArrayList; import java.util.List; import org.project.model.UserDetails; import org.project.model.dao.UserDetailsDao; import com.opensymphony.xwork2.ActionSupport; import com.opensymphony.xwork2.ModelDriven; public class UserAction extends ActionSupport implements ModelDriven<UserDetails>{ private static final long serialVersionUID = -2167265047934268752L; private UserDetails user = new UserDetails(); private UserDetailsDao userDao; private List<UserDetails> userList = new ArrayList<UserDetails>(); @Override public UserDetails getModel(){ return user; } public String add() { userDao.saveUser( user ); return SUCCESS; } public String list() { userList = userDao.listUser(); return SUCCESS; } public String execute(){ return SUCCESS; } /* With all setter and getter methods */ </code></pre> <p>And when I press save button the following error occurs</p> <pre><code>java.lang.NullPointerException org.project.actions.UserAction.add(UserAction.java:26) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) java.lang.reflect.Method.invoke(Unknown Source) com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:440) com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:279) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:242) com.googlecode.s2hibernate.struts2.plugin.s2hibernatevalidator.interceptor.HibernateValidatorInterceptor.intercept(HibernateValidatorInterceptor.java:77) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:163) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:148) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:93) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:128) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) org.apache.struts2.interceptor.ProfilingActivationInterceptor.intercept(ProfilingActivationInterceptor.java:104) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:148) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:128) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) com.googlecode.s2hibernate.struts2.plugin.interceptors.SessionTransactionInjectorInterceptor.intercept(SessionTransactionInjectorInterceptor.java:157) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:236) org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52) org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:468) org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77) org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(Stru tsPrepareAndExecuteFilter.java:76) </code></pre> <p>What maybe wrong? Thanks in advance.</p>

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