http://jdbi.org/: jdbi is designed to provide convenient tabular data access in Java(tm). It uses the Java collections framework for query results, provides a convenient means of externalizing sql statements, and provides named parameter support for any database being used. 
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 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
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 * See the License for the specific language governing permissions and
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package org.jdbi.v3.core.result;

import java.util.stream.Stream;


Reduces row data from a ResultSet into a stream of result elements. Useful for collapsing one-to-many joins. 
Type parameters:
  • <C> – mutable result container type
  • <R> – result element type
See Also:
/**
 * Reduces row data from a {@link java.sql.ResultSet} into a stream of result
 * elements. Useful for collapsing one-to-many joins.
 *
 * @param <C> mutable result container type
 * @param <R> result element type
 * @see ResultBearing#reduceRows(RowReducer)
 */
public interface RowReducer<C, R> {
  
Returns a new, empty result container.

Returns:a new result container.
/**
   * Returns a new, empty result container.
   *
   * @return a new result container.
   */
  C container();

  
Accumulate data from the current row into the result container. Do not attempt to accumulate the RowView itself into the result container--it is only valid within the accumulate() method invocation. Instead, extract mapped types from the RowView by calling RowView.getRow() or RowView.getColumn() and store those values in the container. 
Params:
  • container – the result container
  • rowView – row view over the current result set row.
/**
   * Accumulate data from the current row into the result container. Do not attempt
   * to accumulate the {@link RowView} itself into the result container--it is only
   * valid within the {@link RowReducer#accumulate(Object, RowView) accumulate()}
   * method invocation. Instead, extract mapped types from the RowView by calling
   * {@code RowView.getRow()} or {@code RowView.getColumn()} and store those values
   * in the container.
   *
   * @param container the result container
   * @param rowView row view over the current result set row.
   */
  void accumulate(C container, RowView rowView);

  
Returns a stream of result elements from the result container.

Params:
  • container – the result container
Returns:stream of result elements.
/**
   * Returns a stream of result elements from the result container.
   *
   * @param container the result container
   * @return stream of result elements.
   */
  Stream<R> stream(C container);
}