Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You 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, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.lucene.search; import java.io.IOException; import org.apache.lucene.index.DocValues; import org.apache.lucene.index.LeafReaderContext; import org.apache.lucene.index.NumericDocValues; import org.apache.lucene.index.SortedNumericDocValues; /** * SortField for {@link SortedNumericDocValues}. * <p> * A SortedNumericDocValues contains multiple values for a field, so sorting with * this technique "selects" a value as the representative sort value for the document. * <p> * By default, the minimum value in the list is selected as the sort value, but * this can be customized. * <p> * Like sorting by string, this also supports sorting missing values as first or last, * via {@link #setMissingValue(Object)}. * @see SortedNumericSelector */ public class SortedNumericSortField extends SortField { private final SortedNumericSelector.Type selector; private final SortField.Type type; /** * Creates a sort, by the minimum value in the set * for the document. * @param field Name of field to sort by. Must not be null. * @param type Type of values */ public SortedNumericSortField(String field, SortField.Type type) { this(field, type, false); } /** * Creates a sort, possibly in reverse, by the minimum value in the set * for the document. * @param field Name of field to sort by. Must not be null. * @param type Type of values * @param reverse True if natural order should be reversed. */ public SortedNumericSortField(String field, SortField.Type type, boolean reverse) { this(field, type, reverse, SortedNumericSelector.Type.MIN); } /** * Creates a sort, possibly in reverse, specifying how the sort value from * the document's set is selected. * @param field Name of field to sort by. Must not be null. * @param type Type of values * @param reverse True if natural order should be reversed. * @param selector custom selector type for choosing the sort value from the set. */ public SortedNumericSortField(String field, SortField.Type type, boolean reverse, SortedNumericSelector.Type selector) { super(field, SortField.Type.CUSTOM, reverse); if (selector == null) { throw new NullPointerException(); } if (type == null) { throw new NullPointerException(); } this.selector = selector; this.type = type; } /** Returns the numeric type in use for this sort */ public SortField.Type getNumericType() { return type; } /** Returns the selector in use for this sort */ public SortedNumericSelector.Type getSelector() { return selector; } @Override public int hashCode() { final int prime = 31; int result = super.hashCode(); result = prime * result + selector.hashCode(); result = prime * result + type.hashCode(); return result; } @Override public boolean equals(Object obj) { if (this == obj) return true; if (!super.equals(obj)) return false; if (getClass() != obj.getClass()) return false; SortedNumericSortField other = (SortedNumericSortField) obj; if (selector != other.selector) return false; if (type != other.type) return false; return true; } @Override public String toString() { StringBuilder buffer = new StringBuilder(); buffer.append("<sortednumeric" + ": \"").append(getField()).append("\">"); if (getReverse()) buffer.append('!'); if (missingValue != null) { buffer.append(" missingValue="); buffer.append(missingValue); } buffer.append(" selector="); buffer.append(selector); buffer.append(" type="); buffer.append(type); return buffer.toString(); } @Override public void setMissingValue(Object missingValue) { this.missingValue = missingValue; } @Override public FieldComparator<?> getComparator(int numHits, int sortPos) { switch (type) { case INT: return new FieldComparator.IntComparator(numHits, getField(), (Integer) missingValue) { @Override protected NumericDocValues getNumericDocValues(LeafReaderContext context, String field) throws IOException { return SortedNumericSelector.wrap(DocValues.getSortedNumeric(context.reader(), field), selector, type); } }; case FLOAT: return new FieldComparator.FloatComparator(numHits, getField(), (Float) missingValue) { @Override protected NumericDocValues getNumericDocValues(LeafReaderContext context, String field) throws IOException { return SortedNumericSelector.wrap(DocValues.getSortedNumeric(context.reader(), field), selector, type); } }; case LONG: return new FieldComparator.LongComparator(numHits, getField(), (Long) missingValue) { @Override protected NumericDocValues getNumericDocValues(LeafReaderContext context, String field) throws IOException { return SortedNumericSelector.wrap(DocValues.getSortedNumeric(context.reader(), field), selector, type); } }; case DOUBLE: return new FieldComparator.DoubleComparator(numHits, getField(), (Double) missingValue) { @Override protected NumericDocValues getNumericDocValues(LeafReaderContext context, String field) throws IOException { return SortedNumericSelector.wrap(DocValues.getSortedNumeric(context.reader(), field), selector, type); } }; default: throw new AssertionError(); } } }