How to use

addToMultiValuesMap

method

in

org.apache.sis.internal.util.CollectionsExt

/**
 * Closes this element. This method verifies that there is no unprocessed value (dates,
 * numbers, booleans or strings), but ignores inner elements as required by ISO 19162.
 *
 * This method add the keywords of ignored elements in the {@code ignoredElements} map as below:
 * <ul>
 *   <li><b>Keys</b>: keyword of ignored elements. Note that a key may be null.</li>
 *   <li><b>Values</b>: keywords of all elements containing an element identified by the above-cited key.
 *       This list is used for helping the users to locate the ignored elements.</li>
 * </ul>
 *
 * @param  ignoredElements  the collection where to declare ignored elements.
 * @throws ParseException if the list still contains some unprocessed values.
 */
final void close(final Map<String, List<String>> ignoredElements) throws ParseException {
  if (list != null) {
    for (final Object value : list) {
      if (value instanceof Element) {
        CollectionsExt.addToMultiValuesMap(ignoredElements, ((Element) value).keyword, keyword);
      } else {
        throw new UnparsableObjectException(locale, Errors.Keys.UnexpectedValueInElement_2,
            new Object[] {keyword, value}, offset + keyword.length());
      }
    }
  }
}

/**
 * Closes this element. This method verifies that there is no unprocessed value (dates,
 * numbers, booleans or strings), but ignores inner elements as required by ISO 19162.
 *
 * This method add the keywords of ignored elements in the {@code ignoredElements} map as below:
 * <ul>
 *   <li><b>Keys</b>: keyword of ignored elements. Note that a key may be null.</li>
 *   <li><b>Values</b>: keywords of all elements containing an element identified by the above-cited key.
 *       This list is used for helping the users to locate the ignored elements.</li>
 * </ul>
 *
 * @param  ignoredElements  the collection where to declare ignored elements.
 * @throws ParseException if the list still contains some unprocessed values.
 */
final void close(final Map<String, List<String>> ignoredElements) throws ParseException {
  if (list != null) {
    for (final Object value : list) {
      if (value instanceof Element) {
        CollectionsExt.addToMultiValuesMap(ignoredElements, ((Element) value).keyword, keyword);
      } else {
        throw new UnparsableObjectException(locale, Errors.Keys.UnexpectedValueInElement_2,
            new Object[] {keyword, value}, offset + keyword.length());
      }
    }
  }
}

if (variable.isCoordinateSystemAxis()) {
  for (final Dimension dimension : variable.dimensions) {
    CollectionsExt.addToMultiValuesMap(dimToAxes, dimension, variable);

if (variable.isCoordinateSystemAxis()) {
  for (final Dimension dimension : variable.dimensions) {
    CollectionsExt.addToMultiValuesMap(dimToAxes, dimension, variable);

CollectionsExt.addToMultiValuesMap(aliases, key, key);
name = ((ScopedName) name).tail();
final String alias = name.toString();
final List<String> fullNames = CollectionsExt.addToMultiValuesMap(aliases, alias, key);
if (fullNames.size() > 1) {
  CollectionsExt.addToMultiValuesMap(aliases, alias, alias);

CollectionsExt.addToMultiValuesMap(aliases, key, key);
name = ((ScopedName) name).tail();
final String alias = name.toString();
final List<String> fullNames = CollectionsExt.addToMultiValuesMap(aliases, alias, key);
if (fullNames.size() > 1) {
  CollectionsExt.addToMultiValuesMap(aliases, alias, alias);

if (variable.isCoverage()) {
  final List<String> dimensions = Arrays.asList(variable.getGridDimensionNames());
  CollectionsExt.addToMultiValuesMap(contents, dimensions, variable);

if (variable.isCoverage(2)) {
  final List<String> dimensions = Arrays.asList(variable.getGridDimensionNames());
  CollectionsExt.addToMultiValuesMap(contents, dimensions, variable);

/**
 * Tests {@link CollectionsExt#addToMultiValuesMap(Map, Object, Object)}, then
 * opportunistically tests {@link CollectionsExt#removeFromMultiValuesMap(Map, Object, Object)},
 */
@Test
public void testAddAndRemoveToMultiValuesMap() {
  final Map<String, List<Integer>> map = new LinkedHashMap<>();
  final Integer A1 = 2;
  final Integer A2 = 4;
  final Integer B1 = 3;
  final Integer B2 = 6;
  final Integer B3 = 9;
  assertArrayEquals(new Integer[] {A1},         CollectionsExt.addToMultiValuesMap(map, "A", A1).toArray());
  assertArrayEquals(new Integer[] {B1},         CollectionsExt.addToMultiValuesMap(map, "B", B1).toArray());
  assertArrayEquals(new Integer[] {B1, B2},     CollectionsExt.addToMultiValuesMap(map, "B", B2).toArray());
  assertArrayEquals(new Integer[] {A1, A2},     CollectionsExt.addToMultiValuesMap(map, "A", A2).toArray());
  assertArrayEquals(new Integer[] {B1, B2, B3}, CollectionsExt.addToMultiValuesMap(map, "B", B3).toArray());
  assertArrayEquals(new String[]  {"A", "B"},   map.keySet().toArray());
  assertArrayEquals(new Integer[] {A1, A2},     map.get("A").toArray());
  assertArrayEquals(new Integer[] {B1, B2, B3}, map.get("B").toArray());
  assertNull(                                   CollectionsExt.removeFromMultiValuesMap(map, "C", A2));
  assertArrayEquals(new Integer[] {A1},         CollectionsExt.removeFromMultiValuesMap(map, "A", A2).toArray());
  assertArrayEquals(new Integer[] {B1, B3},     CollectionsExt.removeFromMultiValuesMap(map, "B", B2).toArray());
  assertArrayEquals(new Integer[] {},           CollectionsExt.removeFromMultiValuesMap(map, "A", A1).toArray());
  assertArrayEquals(new String[]  {"B"},        map.keySet().toArray());
  assertArrayEquals(new Integer[] {B1, B3},     map.get("B").toArray());
}

importedKeys.add(relation);
for (final String column : relation.getForeignerKeys()) {
  CollectionsExt.addToMultiValuesMap(foreignerKeys, column, relation);