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3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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23 
24 package org.openjdk.tests.java.util.stream;
25 
26 /*
27  * THE CONTENTS OF THIS FILE HAVE TO BE IN SYNC WITH THE EXAMPLES USED
28  * IN THE JAVADOC.
29  *
30  * @test
31  * @bug 8231161
32  * @compile CollectorExample.java
33  * @summary Compilation test only. Compile code snippets from
34  * java.util.stream.Collector class-level API documentation
35  */
36 
37 import java.util.*;
38 import java.util.function.BiConsumer;
39 import java.util.function.BinaryOperator;
40 import java.util.function.Function;
41 import java.util.function.Supplier;
42 import java.util.stream.Collector;
43 import java.util.stream.Collectors;
44 
45 public class CollectorExample {
46 
47     // Empty helper classes
48 
49     class Widget {
50     }
51 
52     class Employee {
getSalary()53         public int getSalary() {
54             return 0;    // money isn't everything
55         }
56 
getDepartment()57         public Department getDepartment() {
58             return new Department();
59         }
60     }
61 
62     class Department {
63     }
64 
testSnippet1(Collector<T, A, R> collector, T t1, T t2)65     <T, A, R> void testSnippet1(Collector<T, A, R> collector, T t1, T t2) {
66 
67         Supplier<A> supplier = collector.supplier();
68         BiConsumer<A, T> accumulator = collector.accumulator();
69         BinaryOperator<A> combiner = collector.combiner();
70         Function<A, R> finisher = collector.finisher();
71 
72         // Example start
73         A a1 = supplier.get();
74         accumulator.accept(a1, t1);
75         accumulator.accept(a1, t2);
76         R r1 = finisher.apply(a1);
77 
78         A a2 = supplier.get();
79         accumulator.accept(a2, t1);
80         A a3 = supplier.get();
81         accumulator.accept(a3, t2);
82         R r2 = finisher.apply(combiner.apply(a2, a3));
83     }
84 
testSnippet2()85     void testSnippet2() {
86         Collector<Widget, ?, TreeSet<Widget>> intoSet =
87                 Collector.of(TreeSet::new, TreeSet::add,
88                         (left, right) -> { left.addAll(right); return left; });
89     }
90 
testSnippet3(Collector<T, A, R> collector, Collection<T> data)91     <T, A, R> void testSnippet3(Collector<T, A, R> collector, Collection<T> data) {
92         A container = collector.supplier().get();
93         for (T t : data)
94             collector.accumulator().accept(container, t);
95         collector.finisher().apply(container);
96     }
97 
testSnippet4and5()98     void testSnippet4and5() {
99         Collector<Employee, ?, Integer> summingSalaries
100                 = Collectors.summingInt(Employee::getSalary);
101 
102         Collector<Employee, ?, Map<Department, Integer>> summingSalariesByDept
103                 = Collectors.groupingBy(Employee::getDepartment, summingSalaries);
104     }
105 }
106