public Object execute ();
public Object execute (Object param1);
public Object execute (Object param1, Object param2);
public Object execute (Object param1, Object param2, Object param3);
public Object executeWithArray (Object[] params);
public Object executeWithMap (Map params);

As evident from the examples above, queries are executed with one of the many execute methods defined in the Query interface. If your query declares between 0 and 3 parameters, you can use the execute version that takes the corresponding number of Object arguments; each argument should be set to the value of the corresponding declared parameter. For queries with more than 3 parameters, you can use the more generic executeWithArray and executeWithMap methods. See the Query interface Javadoc for details.

All execute methods declare a return type of Object, but they really return Collections. The JDO specification only uses Object rather than Collection to enable vendors to use proprietary return types in certain cases, and to allow for future expansion of the interface.

public void close (Object result);
public void closeAll ();

Query results may hold on to data store resources; therefore, all results should be closed when they are no longer needed. You can close an individual query result with the close method, or all open results at once with closeAll.

Note

Query results from Kodo JDO always implement the java.util.List interface. This allows you to access the results in any order, and supports the common need to only process a certain range of objects in the result set. Because Kodo JDO can be configured to use scrollable JDBC ResultSets where appropriate, list elements that are never accessed will not affect performance. Combined with Kodo JDO's memory-sensitive data structures, scrollable result sets also allow you to efficiently iterate over huge data sets -- even when the entire data set could not possibly fit into memory at once. These scrollable results consume database resources, however, so if you have configured Kodo to use scrolling result sets you are strongly encouraged to close your query results when you are through with them. If they are not closed immediately, they will be closed when they are garbage collected by the JVM.

PersistenceManager pm = ...;

Query query = pm.newQuery (Employee.class, "salary > 50000");
Collection employees = (Collection) query.execute ();
try
{
    for (Iterator itr = employees.iterator (); itr.hasNext ();)
        processEmployee ((Employee) itr.next ());
}
finally
{
    query.close (employees);
}