Merge pull request #9 from furplag/2.x

add Streamr#collect for Map .

pom.xml

@@ -22,7 +22,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>jp.furplag.sandbox</groupId>
   <artifactId>relic</artifactId>
-  <version>2.1.0-SNAPSHOT</version>
+  <version>2.1.0</version>
   <packaging>jar</packaging>
   <inceptionYear>2018</inceptionYear>
   <name>${project.artifactId}</name>

src/main/java/jp/furplag/sandbox/reflect/SavageReflection.java

@@ -20,7 +20,6 @@
 import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.Map;
-import java.util.function.Predicate;
 
 import org.apache.commons.lang3.ArrayUtils;
 

src/main/java/jp/furplag/sandbox/stream/Streamr.java

@@ -18,15 +18,20 @@
 
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.HashMap;
+import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.function.BinaryOperator;
 import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 import java.util.function.UnaryOperator;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+import org.apache.commons.lang3.tuple.Pair;
+
 import jp.furplag.function.ThrowablePredicate;
 
 /**
@@ -48,6 +53,18 @@ static <T, R extends Collection<T>> R collect(final Stream<T> stream, final Supp
     return stream(stream).collect(Collectors.toCollection(supplier));
   }
 
+  /**
+   * we might to use this many .
+   *
+   * @param <T> the type of the key of stream elements
+   * @param <U> the type of the value of stream elements
+   * @param entries {@link Stream} of {@link Pair}, maybe null
+   * @return {@link Map}
+   */
+  static <T, U> Map<T, U> collect(final Stream<Pair<T, U>> entries, BinaryOperator<U> mergeFunction, final Supplier<Map<T, U>> supplier) {
+    return Streamr.stream(entries).collect(Collectors.toMap(Pair::getLeft, Pair::getRight, Objects.requireNonNullElse(mergeFunction, (current, next) -> next), Objects.requireNonNullElse(supplier, HashMap::new)));
+  }
+
   /**
    * do less coding in case of {@link Collection#stream()} .
    *

src/test/java/jp/furplag/sandbox/stream/StreamrTest.java

@@ -23,17 +23,21 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.Deque;
 import java.util.HashSet;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Objects;
 import java.util.Queue;
 import java.util.Set;
 import java.util.concurrent.DelayQueue;
 import java.util.function.Function;
+import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 import java.util.stream.Stream;
 
+import org.apache.commons.lang3.tuple.Pair;
 import org.junit.Test;
 
 import jp.furplag.sandbox.stream.Streamr.Filter.FilteringMode;
@@ -148,6 +152,17 @@ public void testToSet() {
     assertEquals(new HashSet<>(Arrays.asList(new Integer[] { 1, 2, 3 })), Streamr.collect(Streamr.stream(new Integer[] { 1, null, 2, null, 3 }), HashSet::new));
   }
 
+  @Test
+  public void testToMap() {
+    assertEquals(Collections.emptyMap(), Streamr.collect(Stream.of((Pair<Integer, Integer>) null), null, null));
+    assertThat(Streamr.collect(Stream.of((Pair<Integer, Integer>) null, Pair.of(1, 2)), null, null).toString(), is("{1=2}"));
+    assertEquals(Stream.of(1, 2).map((x) -> Pair.of(x, x)).collect(Collectors.toMap(Pair::getLeft, Pair::getRight)), Streamr.collect(Stream.of((Pair<Integer, Integer>) null, Pair.of(2, 2), Pair.of(1, 1)), null, null));
+    assertThat(Streamr.collect(Stream.of((Pair<Integer, Integer>) null, Pair.of(1, 2), Pair.of(1, 1)), null, null).toString(), is("{1=1}"));
+    assertThat(Streamr.collect(Stream.of((Pair<Integer, Integer>) null, Pair.of(1, 2), Pair.of(1, 1)), (a, b) -> a, null).toString(), is("{1=2}"));
+    assertThat(Streamr.collect(Stream.of((Pair<Integer, Integer>) null, Pair.of(2, 2), Pair.of(1, 1), Pair.of(1, 2)), (a, b) -> b, LinkedHashMap::new).toString(), is("{2=2, 1=2}"));
+    assertThat(Streamr.collect(Stream.of((Pair<Integer, Integer>) Pair.of(2, 2), Pair.of(1, 1), Pair.of(1, 2)).sorted(Comparator.comparing(Pair::getLeft)), (a, b) -> b, LinkedHashMap::new).toString(), is("{1=2, 2=2}"));
+  }
+
   @Test
   public void testFilteringMode() {
     assertThat(Streamr.Filter.FilteringMode.And.and(), is(true));