Inserting to Oracle Nested Table in Java

I want to write a Java program that will insert a row to a table that has a number of nested tables. Following that, I want to insert an unpredictable number of rows to each of these nested tables.

There are lots of examples a PreparedStatement of this sort:

    new PreparedStatement("INSERT INTO CONTAINER_TBL (A, B, NESTED_TBL)
        VALUES ('X', 'Y', 
            NESTED_TBL_TYPE(NESTED_ROW_TYPE('Q', 99),
                            NESTED_ROW_TYPE('R', 999))
         )");

This is fine if I know ahead of time how many nested rows I'll need to insert. But what if I don't?

Pass a Java array as a collection:

Oracle 12c Setup:

CREATE USER test_user IDENTIFIED BY password;
GRANT CREATE SESSION TO test_user;
ALTER USER test_user QUOTA UNLIMITED ON users;

CREATE TYPE test_user.nested_row_type AS OBJECT( a CHAR(1), b INTEGER );
/

CREATE TYPE test_user.nested_tbl_type AS TABLE OF test_user.nested_row_type;
/

CREATE TABLE test_user.container_tbl(
  a CHAR(1),
  b CHAR(1),
  nested_tbl test_user.nested_tbl_type
) NESTED TABLE nested_tbl STORE AS nested_tbl_tbl;

Java: (Using ojdbc7.jar)

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import oracle.jdbc.OracleConnection;
import oracle.jdbc.OraclePreparedStatement;
import oracle.sql.ARRAY;

public class LoadOracleObjectCollection {
  public static void main(String[] args) {
    try{
      Class.forName("oracle.jdbc.OracleDriver");

      Connection con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl","test_user","password");

      Object[] objs = new Object[]{
        con.createStruct( "NESTED_ROW_TYPE", new Object[]{ "Q", 99 } ),
        con.createStruct( "NESTED_ROW_TYPE", new Object[]{ "R", 999 } )
      };

      ARRAY a = ((OracleConnection) con).createARRAY("NESTED_TBL_TYPE", objs);

      PreparedStatement st = con.prepareCall( "INSERT INTO container_tbl ( a, b, nested_tbl ) VALUES ( ?, ?, ? )" );

      st.setString( 1, "x" );
      st.setString( 2, "y" );
      ((OraclePreparedStatement) st).setARRAY( 3 , a );
      st.execute();
      st.close();
      con.close();
    } catch(ClassNotFoundException | SQLException e) {
      System.out.println(e);
    }
  }
}

Oracle Query

SELECT c.a, c.b, n.a, n.b
FROM   test_user.container_tbl c
       CROSS JOIN TABLE( c.nested_tbl ) n;

Results:

A B A          B
- - - ----------
x y Q         99
x y R        999

Version with older syntax:

Just passing to and from a dummy query (rather than inserting into the database) to also show how to retrieve an array of objects:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import oracle.jdbc.OracleConnection;
import oracle.jdbc.OraclePreparedStatement;
import oracle.sql.ARRAY;
import oracle.sql.ArrayDescriptor;
import oracle.sql.Datum;
import oracle.sql.STRUCT;
import oracle.sql.StructDescriptor;

public class ArrayOfObjectsTest
{
  public static void main( final String[] args ){
    try{
      Class.forName( "oracle.jdbc.OracleDriver" );

      Connection con = DriverManager.getConnection("jdbc:oracle:thin:@localhost:1521:orcl","test_user","password");

      OracleConnection oc = (OracleConnection) con;
      StructDescriptor sd = new StructDescriptor( "NESTED_ROW_TYPE", oc );
      ArrayDescriptor  ad = new ArrayDescriptor( "NESTED_TBL_TYPE", oc );

      ARRAY array = new ARRAY( ad,oc,new STRUCT[]{
        new STRUCT(sd,oc,new Object[]{ 'P',99 } ),
        new STRUCT(sd,oc,new Object[]{ 'Q',999 } )
      } );

      OraclePreparedStatement st = (OraclePreparedStatement) con.prepareStatement( "SELECT ? FROM DUAL" );
      st.setARRAY( 1, array);
      ResultSet rs = st.executeQuery();

      while( rs.next() )
      {
        Object[] structs = (Object[]) rs.getArray( 1 ).getArray();
        for ( Object struct : structs )
        {
          Datum[] datums = ((STRUCT) struct).getOracleAttributes();
          System.out.println( datums[0].stringValue() + ", " + datums[1].intValue() ) );
        }
      }
      st.close();
      con.close();
    } catch (ClassNotFoundException | SQLException ex) {
      System.out.println( ex.getMessage() );
      ex.printStackTrace();
    }
  }  
}

Output: