在Java中添加艺术家(人员)时出错
我正在用Java创建一个软件,它应该能够注册艺术家、专辑和曲目 一切都连接到一个在Java中添加艺术家(人员)时出错,java,Java,我正在用Java创建一个软件,它应该能够注册艺术家、专辑和曲目 一切都连接到一个MySQL数据库,该软件只需要艺术家的名字,我向您展示我创建的方法。很抱歉,很多名字都是西班牙语的,但是这个 是为了我的学校,我不能用太多的英语单词。我想你能理解 这是连接DB的类Conexión: public class Conexion { Connection conexion=null; /*Conectamos a la Base de Datos*/ public Conexion(){
MySQL数据库
,该软件只需要艺术家的名字,我向您展示我创建的方法。很抱歉,很多名字都是西班牙语的,但是这个
是为了我的学校,我不能用太多的英语单词。我想你能理解
这是连接DB的类Conexión
:
public class Conexion {
Connection conexion=null;
/*Conectamos a la Base de Datos*/
public Conexion(){
try{
Class.forName("com.mysql.jdbc.Driver");
conexion=DriverManager.getConnection("jdbc:mysql://localhost/chinook", "root", "");
}catch(Exception excepcion){
excepcion.printStackTrace();
}
}
/*Devolvemos la conexion*/
public Connection getConnection(){
return conexion;
}
/*Cerramos la conexión a la Base de Datos*/
public void desconectar(){
try{
conexion.close();
}catch(Exception excepcion){
excepcion.printStackTrace();
}
}
}
这是类Coordinador
,该类用于实现不同类之间的联合(遵循MVC模型),我向您粘贴添加艺术家的部分,其他部分仅与视图相关:
public void addArtista(ArtistaVO artistaVO){
miLogica.validarRegistroArtista(artistaVO);
}
类ArtistaVO
我在其中创建艺术家的get和set:
public class ArtistaVO {
private int idArtista;
private String nombreArtista;
public int getIdArtista(){
return idArtista;
}
public void setIdArtista(int idArtista){
this.idArtista=idArtista;
}
public String getNombreArtista(){
return nombreArtista;
}
public void setNombreArtista(String nombreArtista){
this.nombreArtista=nombreArtista;
}
}
public void addArtista(ArtistaVO artistaVO){
Conexion conexion=new Conexion();
try{
//Insertamos los datos del Artista
PreparedStatement sqlAddArtist=conexion.getConnection().prepareStatement("INSERT into artist values(?,?)");
ResultSet resultado=sqlAddArtist.executeQuery();
while(resultado.next()){
sqlAddArtist.setString(1, artistaVO.getNombreArtista());
sqlAddArtist.setInt(2, getMaxId()+1);
}
JOptionPane.showMessageDialog(null, "Se ha añadido exitosamente","Información",JOptionPane.INFORMATION_MESSAGE);
sqlAddArtist.close();
conexion.desconectar();
}catch(SQLException excepcion){
System.out.println(excepcion.getMessage());
JOptionPane.showMessageDialog(null,"No se registro", "Error", JOptionPane.ERROR_MESSAGE);
}
}
注册艺术家的方法:
public class ArtistaVO {
private int idArtista;
private String nombreArtista;
public int getIdArtista(){
return idArtista;
}
public void setIdArtista(int idArtista){
this.idArtista=idArtista;
}
public String getNombreArtista(){
return nombreArtista;
}
public void setNombreArtista(String nombreArtista){
this.nombreArtista=nombreArtista;
}
}
public void addArtista(ArtistaVO artistaVO){
Conexion conexion=new Conexion();
try{
//Insertamos los datos del Artista
PreparedStatement sqlAddArtist=conexion.getConnection().prepareStatement("INSERT into artist values(?,?)");
ResultSet resultado=sqlAddArtist.executeQuery();
while(resultado.next()){
sqlAddArtist.setString(1, artistaVO.getNombreArtista());
sqlAddArtist.setInt(2, getMaxId()+1);
}
JOptionPane.showMessageDialog(null, "Se ha añadido exitosamente","Información",JOptionPane.INFORMATION_MESSAGE);
sqlAddArtist.close();
conexion.desconectar();
}catch(SQLException excepcion){
System.out.println(excepcion.getMessage());
JOptionPane.showMessageDialog(null,"No se registro", "Error", JOptionPane.ERROR_MESSAGE);
}
}
此方法用于创建艺术家ID:
public int getMaxId(){
int id=0;
Conexion conexion=new Conexion();
try{
Statement sqlMaxId=conexion.getConnection().createStatement();
ResultSet resultado=sqlMaxId.executeQuery("SELECT max(ArtistId) from artist");
if(resultado.next()){
id=resultado.getInt(0);
}
conexion.desconectar();
sqlMaxId.close();
}catch(SQLException excepcion){
System.out.println(excepcion.getMessage());
}
return id;
}
这属于单击按钮后注册艺术家的窗口:
public void actionPerformed(ActionEvent evento) {
if(evento.getSource()==botonAñadir){
try{
ArtistaVO artistaVO=new ArtistaVO();
artistaVO.setNombreArtista(campoTextoArtista.getText());
miCoordinador.addArtista(artistaVO);
}catch(Exception excepcion){
JOptionPane.showMessageDialog(null, "Error al añadir Artista", "Error", JOptionPane.ERROR_MESSAGE);
}
}
}
我得到的错误是error al añadir Artista
(错误添加艺术家),我不知道故障可能在哪里
这是我得到的例外:
java.lang.NullPointerException
at controlador.Coordinador.addArtista(Coordinador.java:108)
at vista.VistaArtistasAdd.actionPerformed(VistaArtistasAdd.java:70)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
这是方法ValidarRegistrotista
:
public void validarRegistroArtista(ArtistaVO artistaVO){
ArtistaDAO artistaDAO;
if(artistaVO.getIdArtista()>=0){
artistaDAO=new ArtistaDAO();
artistaDAO.addArtista(artistaVO);
}else{
JOptionPane.showMessageDialog(null, "Debe de introducirse algún numero de ID", "Advertencia", JOptionPane.WARNING_MESSAGE);
}
}
您正在绑定值之前执行数据库查询
PreparedStatement sqlAddArtist=conexion.getConnection().prepareStatement("INSERT into artist values(?,?)");
ResultSet resultado=sqlAddArtist.executeQuery();
while(resultado.next()){
sqlAddArtist.setString(1, artistaVO.getNombreArtista());
sqlAddArtist.setInt(2, getMaxId()+1);
}
这应该是这样的:
PreparedStatement sqlAddArtist=conexion.getConnection().prepareStatement("INSERT into artist values(?,?)");
sqlAddArtist.setString(1, artistaVO.getNombreArtista());
sqlAddArtist.setInt(2, getMaxId()+1);
sqlAddArtist.execute();
您正在绑定值之前执行数据库查询
PreparedStatement sqlAddArtist=conexion.getConnection().prepareStatement("INSERT into artist values(?,?)");
ResultSet resultado=sqlAddArtist.executeQuery();
while(resultado.next()){
sqlAddArtist.setString(1, artistaVO.getNombreArtista());
sqlAddArtist.setInt(2, getMaxId()+1);
}
这应该是这样的:
PreparedStatement sqlAddArtist=conexion.getConnection().prepareStatement("INSERT into artist values(?,?)");
sqlAddArtist.setString(1, artistaVO.getNombreArtista());
sqlAddArtist.setInt(2, getMaxId()+1);
sqlAddArtist.execute();
错误位于第
Coordinador.java:108行,是一个NullPointerException
。。。原因?我们应该看到的代码是:miLogica.validarregistoratista(artistaVO)但是我可以打赌artistaVO==null
。。。。也。。。刚刚添加了method@nadir似乎是对的。。。按照步骤,让我们知道,也检查重复的问题,NPE只需要本地化。。。。最后,请告诉你们的老师,在西班牙语社团生活中,我们用英语写代码……错误在第Coordinador.java:108行,是一个NullPointerException
。。。原因?我们应该看到的代码是:miLogica.validarregistoratista(artistaVO)但是我可以打赌artistaVO==null
。。。。也。。。刚刚添加了method@nadir似乎是对的。。。按照步骤,让我们知道,也检查重复的问题,NPE只需要本地化。。。。最后,请告诉你们的老师,在西班牙社团生活中,我们用英语写代码。。。