Add toImmutableSortedListBy to Collectors2.Closes #1136

Signed-off-by: Utkarsh Nagar <utkarshnagar2000@gmail.com> reword Add toImmutableSortedListBy to Collectors2.Closes#1136 Signed-off-by: Utkarsh Nagar <utkarshnagar2000@gmail.com>
eclipse · Sep 17, 2021 · db29e86 · db29e86
1 parent 22b5d9a
commit db29e86
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diff --git a/eclipse-collections/src/main/java/org/eclipse/collections/impl/collector/Collectors2.java b/eclipse-collections/src/main/java/org/eclipse/collections/impl/collector/Collectors2.java
@@ -491,6 +491,21 @@ private Collectors2()
                 EMPTY_CHARACTERISTICS);
     }
 
+    /**
+     * <p>Returns the elements as a ImmutableList that has been sorted using the specified comparator.</p>
+     * <p>Examples:</p>
+     * {@code ImmutableList<Integer> list1 = Interval.oneTo(5).stream().collect(Collectors2.toImmutableSortedListBy(Object::toString));}<br>
+     * {@code ImmutableList<Integer> list2 = Interval.oneTo(5).reduceInPlace(Collectors2.toImmutableSortedListBy(Object::toString));}
+     * <p>
+     * Equivalent to using @{@link RichIterable#toImmutableSortedListBy(Function)}}
+     * </p>
+     * {@code ImmutableList<Integer> list = Interval.oneTo(5).toImmutableSortedListBy(Object::toString);}
+     */
+    public static <T, V extends Comparable<? super V>> Collector<T, ?, ImmutableList<T>> toImmutableSortedListBy(Function<? super T, ? extends V> function)
+    {
+        return Collectors2.toImmutableSortedList(Comparators.byFunction(function));
+    }
+
     /**
      * <p>Returns the elements as a MutableSortedBag.</p>
      * <p>Examples:</p>

diff --git a/unit-tests/src/test/java/org/eclipse/collections/impl/collector/Collectors2Test.java b/unit-tests/src/test/java/org/eclipse/collections/impl/collector/Collectors2Test.java
@@ -950,6 +950,27 @@ public void toImmutableSortedListParallel()
         Assert.assertEquals(expected, actual2);
     }
 
+    @Test
+    public void toImmutableSortedListBy()
+    {
+        MutableList<Integer> expected = SMALL_INTERVAL.toSortedListBy(Object::toString);
+        ImmutableList<Integer> actual = this.smallData.stream().collect(Collectors2.toImmutableSortedListBy(Object::toString));
+        Assert.assertEquals(expected, actual);
+        ImmutableList<Integer> actual2 = SMALL_INTERVAL.reduceInPlace(Collectors2.toImmutableSortedListBy(Object::toString));
+        Assert.assertEquals(expected, actual2);
+    }
+
+    @Test
+    public void toImmutableSortedListByParallel()
+    {
+        MutableList<Integer> expected = LARGE_INTERVAL.toSortedListBy(Object::toString);
+        ImmutableList<Integer> actual =
+                this.bigData.parallelStream().collect(Collectors2.toImmutableSortedListBy(Object::toString));
+        Assert.assertEquals(expected, actual);
+        ImmutableList<Integer> actual2 = LARGE_INTERVAL.reduceInPlace(Collectors2.toImmutableSortedListBy(Object::toString));
+        Assert.assertEquals(expected, actual2);
+    }
+
     @Test
     public void toSortedListWithComparator()
     {