-
Notifications
You must be signed in to change notification settings - Fork 103
Expand file tree
/
Copy pathIntSummaryStatistics.java
More file actions
171 lines (160 loc) · 4.67 KB
/
IntSummaryStatistics.java
File metadata and controls
171 lines (160 loc) · 4.67 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
/*
* Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*/
package java.util;
import java.util.function.IntConsumer;
import java.util.stream.Collector;
/**
* 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());
}
}