| /* |
| * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| package java.util; |
| |
| import java.util.function.IntConsumer; |
| |
| /** |
| * A state object for collecting statistics such as count, min, max, sum, and |
| * average. |
| * |
| * <p>This class is designed to work with (though does not require) |
| * {@linkplain java.util.stream streams}. For example, you can compute |
| * summary statistics on a stream of ints with: |
| * <pre> {@code |
| * IntSummaryStatistics stats = intStream.collect(IntSummaryStatistics::new, |
| * IntSummaryStatistics::accept, |
| * IntSummaryStatistics::combine); |
| * }</pre> |
| * |
| * <p>{@code IntSummaryStatistics} can be used as a |
| * {@linkplain java.util.stream.Stream#collect(Collector) reduction} |
| * target for a {@linkplain java.util.stream.Stream stream}. For example: |
| * |
| * <pre> {@code |
| * IntSummaryStatistics stats = people.stream() |
| * .collect(Collectors.summarizingInt(Person::getDependents)); |
| *}</pre> |
| * |
| * This computes, in a single pass, the count of people, as well as the minimum, |
| * maximum, sum, and average of their number of dependents. |
| * |
| * @implNote This implementation is not thread safe. However, it is safe to use |
| * {@link java.util.stream.Collectors#summarizingInt(java.util.function.ToIntFunction) |
| * Collectors.toIntStatistics()} on a parallel stream, because the parallel |
| * implementation of {@link java.util.stream.Stream#collect Stream.collect()} |
| * provides the necessary partitioning, isolation, and merging of results for |
| * safe and efficient parallel execution. |
| * |
| * <p>This implementation does not check for overflow of the sum. |
| * @since 1.8 |
| */ |
| public class IntSummaryStatistics implements IntConsumer { |
| private long count; |
| private long sum; |
| private int min = Integer.MAX_VALUE; |
| private int max = Integer.MIN_VALUE; |
| |
| /** |
| * Construct an empty instance with zero count, zero sum, |
| * {@code Integer.MAX_VALUE} min, {@code Integer.MIN_VALUE} max and zero |
| * average. |
| */ |
| public IntSummaryStatistics() { } |
| |
| /** |
| * Records a new value into the summary information |
| * |
| * @param value the input value |
| */ |
| @Override |
| public void accept(int value) { |
| ++count; |
| sum += value; |
| min = Math.min(min, value); |
| max = Math.max(max, value); |
| } |
| |
| /** |
| * Combines the state of another {@code IntSummaryStatistics} into this one. |
| * |
| * @param other another {@code IntSummaryStatistics} |
| * @throws NullPointerException if {@code other} is null |
| */ |
| public void combine(IntSummaryStatistics other) { |
| count += other.count; |
| sum += other.sum; |
| min = Math.min(min, other.min); |
| max = Math.max(max, other.max); |
| } |
| |
| /** |
| * Returns the count of values recorded. |
| * |
| * @return the count of values |
| */ |
| public final long getCount() { |
| return count; |
| } |
| |
| /** |
| * Returns the sum of values recorded, or zero if no values have been |
| * recorded. |
| * |
| * @return the sum of values, or zero if none |
| */ |
| public final long getSum() { |
| return sum; |
| } |
| |
| /** |
| * Returns the minimum value recorded, or {@code Integer.MAX_VALUE} if no |
| * values have been recorded. |
| * |
| * @return the minimum value, or {@code Integer.MAX_VALUE} if none |
| */ |
| public final int getMin() { |
| return min; |
| } |
| |
| /** |
| * Returns the maximum value recorded, or {@code Integer.MIN_VALUE} if no |
| * values have been recorded. |
| * |
| * @return the maximum value, or {@code Integer.MIN_VALUE} if none |
| */ |
| public final int getMax() { |
| return max; |
| } |
| |
| /** |
| * Returns the arithmetic mean of values recorded, or zero if no values have been |
| * recorded. |
| * |
| * @return the arithmetic mean of values, or zero if none |
| */ |
| public final double getAverage() { |
| return getCount() > 0 ? (double) getSum() / getCount() : 0.0d; |
| } |
| |
| @Override |
| /** |
| * {@inheritDoc} |
| * |
| * Returns a non-empty string representation of this object suitable for |
| * debugging. The exact presentation format is unspecified and may vary |
| * between implementations and versions. |
| */ |
| public String toString() { |
| return String.format( |
| "%s{count=%d, sum=%d, min=%d, average=%f, max=%d}", |
| this.getClass().getSimpleName(), |
| getCount(), |
| getSum(), |
| getMin(), |
| getAverage(), |
| getMax()); |
| } |
| } |