Salve a tutti,

premetto che sono alle prime armi con java e probabilmente il mio errore è dovuto alla mia ignoranza in materia.

Il codice che mi restituisce l'errore è il seguente:

codice:
public void eseguiQueryUpdate(String qry){ 
query = qry; int ru = 0; 
try{ 
   Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); 
   conn = DriverManager.getConnection(URL,"root","matumba"); 
   ps = conn.prepareStatement(query);
   try { 
      pu.executeUpdate();
    } 
   catch (SQLException e) {
   e.printStackTrace();
    } 
   } 
   catch(Exception ex){
    ex.printStackTrace();
    }
}
l'errore invece è:

java.lang.NullPointerException
at cavalli.util.dbconn.ManagerConnection.eseguiQueryU pdate(ManagerConnection.java:51)
at cavalli.util.servlet.Registrazione.processData(Reg istrazione.java:98)
at cavalli.util.servlet.Registrazione.doGet(Registraz ione.java:34)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:717)
at org.apache.catalina.core.ApplicationFilterChain.in ternalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.do Filter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invo ke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invo ke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke( StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke (ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invok e(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.servic e(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(H ttp11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11Conn ectionHandler.process(Http11Protocol.java:602)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run( JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)
java.lang.NullPointerException
at cavalli.util.dbconn.ManagerConnection.eseguiQueryU pdate(ManagerConnection.java:51)
at cavalli.util.servlet.Registrazione.processData(Reg istrazione.java:109)
at cavalli.util.servlet.Registrazione.doGet(Registraz ione.java:34)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:717)
at org.apache.catalina.core.ApplicationFilterChain.in ternalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.do Filter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invo ke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invo ke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke( StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke (ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invok e(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.servic e(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(H ttp11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11Conn ectionHandler.process(Http11Protocol.java:602)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run( JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)
java.lang.NullPointerException
at cavalli.util.dbconn.ManagerConnection.eseguiQueryU pdate(ManagerConnection.java:51)
at cavalli.util.servlet.Registrazione.processData(Reg istrazione.java:120)
at cavalli.util.servlet.Registrazione.doGet(Registraz ione.java:34)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:717)
at org.apache.catalina.core.ApplicationFilterChain.in ternalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.do Filter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invo ke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invo ke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke( StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke (ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invok e(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.servic e(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11Processor.process(H ttp11Processor.java:859)
at org.apache.coyote.http11.Http11Protocol$Http11Conn ectionHandler.process(Http11Protocol.java:602)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run( JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)


Ho provato a fare una stampa delle query che mi restituiscono le exception ma mi sembrano corrette in tutto e per tutto.

Il DB su cui lavoro è MySql.

Ho davvero bisogno di una mano.

Grazie mille.