[postgis] ClassCastException with PostGis Example

[Paul Ramsey]

Some tests might help see where things are breaking:
- Print out obj.toString() before casting it.
- Retrieve the geometry column as a String and print that out too.

Silvio wrote:
> 
> Hi,
> 
> I have just installed PostGis with PostGreSql but the PostGis Example
> doesn't work.
> 
> This is the example (http://postgis.refractions.net/docs/x441.html)
> 
> import java.sql.*;
>   import java.util.*;
>   import java.lang.*;
>   import org.postgis.*;
> 
>   public class JavaGIS {
>     public static void main(String[] args)
>     {
>       java.sql.Connection conn;
>       try
>       {
>         /*
>         * Load the JDBC driver and establish a connection.
>         */
>         Class.forName("org.postgresql.Driver");
>         String url = "jdbc:postgresql://localhost:5432/database";
>         conn = DriverManager.getConnection(url, "postgres", "");
> 
>         /*
>         * Add the geometry types to the connection. Note that you
>         * must cast the connection to the pgsql-specific connection *
> implementation before calling the addDataType() method.
>         */
> 
> ((org.postgresql.Connection)conn).addDataType("geometry","org.postgis.PGgeom
> etry");
> 
> ((org.postgresql.Connection)conn).addDataType("box3d","org.postgis.PGbox3d")
> ;
> 
>                   /*
>         * Create a statement and execute a select query.
>         */
>         Statement s = conn.createStatement();
>         ResultSet r = s.executeQuery("select AsText(geom) as geom,id from
> geomtable");
>         while( r.next() )
>         {
>           /*
>           * Retrieve the geometry as an object then cast it to the geometry
> type.
>           * Print things out.
>           */
> 
>           PGgeometry geom = (PGgeometry)r.getObject(1);
> ********************CAST ERROR*****************
> 
>           int id = r.getInt(2);
>                       System.out.println("Row " + id + ":");
>           System.out.println(geom.toString());
>         }
>                   s.close();
>         conn.close();
>       }
>       catch( Exception e )
>       {
>         e.printStackTrace();
>       }
>     }
>   }
> 
> The compiling phase is ok
> After, when I try to run the class I get the following error:
> 
> java.lang.ClassCastException: java.lang.String
>         at PostGis.main(PostGis.java:42)
> 
> (the error is referred to the line 42 where I have written "CAST ERROR")
> 
> I hope that somebody can help me!!
> 
> Thanks in advance.
> 
> Silvio B.
> 
> 
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> 
> 
> 
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-- 
      __
     /
     | Paul Ramsey
     | Refractions Research
     | Email: pramsey at refractions.net
     | Phone: (250) 885-0632
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