Add object methods support for the sortBy(), groupBy(), countBy() and

indexBy().

Author: javadev

src/main/java/com/github/underscore/$.java

@@ -504,8 +504,8 @@ public static <E> Set<E> sample(final List<E> list, final int howMany) {
         return samples;
     }
 
-    public static <E, T extends Comparable<? super T>> List<E> sortBy(final List<E> list, final Function1<E, T> func) {
-        final List<E> sortedList = newArrayList(list);
+    public static <E, T extends Comparable<? super T>> List<E> sortBy(final Iterable<E> iterable, final Function1<E, T> func) {
+        final List<E> sortedList = newArrayList(iterable);
         Collections.sort(sortedList, new Comparator<E>() {
             @Override
             public int compare(E o1, E o2) {
@@ -515,8 +515,12 @@ public int compare(E o1, E o2) {
         return sortedList;
     }
 
-    public static <K, V extends Comparable<? super V>> List<Map<K, V>> sortBy(final List<Map<K, V>> list, final K key) {
-        final List<Map<K, V>> sortedList = newArrayList(list);
+    public <E, T extends Comparable<? super T>> List<E> sortBy(final Function1<E, T> func) {
+        return sortBy((Iterable<E>) iterable, func);
+    }
+
+    public static <K, V extends Comparable<? super V>> List<Map<K, V>> sortBy(final Iterable<Map<K, V>> iterable, final K key) {
+        final List<Map<K, V>> sortedList = newArrayList(iterable);
         Collections.sort(sortedList, new Comparator<Map<K, V>>() {
             @Override
             public int compare(Map<K, V> o1, Map<K, V> o2) {
@@ -542,6 +546,10 @@ public static <K, E> Map<K, List<E>> groupBy(final Iterable<E> iterable, final F
         return retVal;
     }
 
+    public <K, E> Map<K, List<E>> groupBy(final Function1<E, K> func) {
+        return groupBy((Iterable<E>) iterable, func);
+    }
+
     public static <K, E> Map<K, List<E>> indexBy(final Iterable<E> iterable, final String property) {
         return groupBy(iterable, new Function1<E, K>() {
             @Override
@@ -555,6 +563,10 @@ public K apply(E elem) {
         });
     }
 
+    public <K, E> Map<K, List<E>> indexBy(final String property) {
+        return indexBy((Iterable<E>) iterable, property);
+    }
+
     public static <K, E> Map<K, Integer> countBy(final Iterable<E> iterable, Function1<E, K> func) {
         final Map<K, Integer> retVal = newLinkedHashMap();
         for (E e : iterable) {
@@ -568,6 +580,10 @@ public static <K, E> Map<K, Integer> countBy(final Iterable<E> iterable, Functio
         return retVal;
     }
 
+    public <K, E> Map<K, Integer> countBy(Function1<E, K> func) {
+        return countBy((Iterable<E>) iterable, func);
+    }
+
     public static <E> E[] toArray(final Iterable<E> iterable) {
         return (E[]) newArrayList(iterable).toArray();
     }

src/test/java/com/github/underscore/CollectionsTest.java

@@ -771,6 +771,14 @@ public Integer apply(Integer item) {
             }
         });
         assertEquals("[5, 4, 6, 3, 1, 2]", result.toString());
+        final List<Integer> resultObj =
+        new $(asList(1, 2, 3, 4, 5, 6)).sortBy(
+            new Function1<Integer, Integer>() {
+            public Integer apply(Integer item) {
+                return Double.valueOf(Math.sin(item) * 1000).intValue();
+            }
+        });
+        assertEquals("[5, 4, 6, 3, 1, 2]", resultObj.toString());
     }
 
 /*
@@ -808,6 +816,14 @@ public Double apply(Double num) {
             }
         });
         assertEquals("{1.0=[1.3], 2.0=[2.1, 2.4]}", result.toString());
+        final Map<Double, List<Double>> resultObj =
+        new $(asList(1.3, 2.1, 2.4)).groupBy(
+            new Function1<Double, Double>() {
+            public Double apply(Double num) {
+                return Math.floor(num);
+            }
+        });
+        assertEquals("{1.0=[1.3], 2.0=[2.1, 2.4]}", resultObj.toString());
     }
 
 /*
@@ -835,6 +851,9 @@ public String toString() {
         final Map<String, List<Person>> result =
         $.indexBy(asList(new Person("moe", 40), new Person("larry", 50), new Person("curly", 60)), "age");
         assertEquals("{40=[moe, 40], 50=[larry, 50], 60=[curly, 60]}", result.toString());
+        final Map<String, List<Person>> resultObj =
+        new $(asList(new Person("moe", 40), new Person("larry", 50), new Person("curly", 60))).indexBy("age");
+        assertEquals("{40=[moe, 40], 50=[larry, 50], 60=[curly, 60]}", resultObj.toString());
         final Map<String, List<Person>> result2 =
         $.indexBy(asList(new Person("moe", 40), new Person("larry", 50), new Person("curly", 60)), "age2");
         assertEquals("{null=[moe, 40, larry, 50, curly, 60]}", result2.toString());
@@ -866,6 +885,14 @@ public String apply(Person person) {
             }
         });
         assertEquals("{moe=2, curly=1}", result.toString());
+        final Map<String, Integer> resultObj =
+        new $(asList(new Person("moe", 40), new Person("moe", 50), new Person("curly", 60))).countBy(
+            new Function1<Person, String>() {
+            public String apply(Person person) {
+                return person.name;
+            }
+        });
+        assertEquals("{moe=2, curly=1}", resultObj.toString());
     }
 
 /*

src/test/java/com/github/underscore/UnderscoreTest.java

@@ -220,4 +220,19 @@ public void optional() {
         assertEquals("Optional.absent()", Optional.absent().toString());
         assertEquals("Optional.of(1)", Optional.of(1).toString());
     }
+
+    @Test
+    public void stackoverflow() {
+        // http://stackoverflow.com/questions/109383/how-to-sort-a-mapkey-value-on-the-values-in-java?rq=1
+        assertEquals("[D=67.3, B=67.4, C=67.4, A=99.5]", $.sortBy((new LinkedHashMap<String, Double>() { {
+            put("A", 99.5);
+            put("B", 67.4);
+            put("C", 67.4);
+            put("D", 67.3);
+        } }).entrySet(), new Function1<Map.Entry<String, Double>, Double>() {
+            public Double apply(Map.Entry<String, Double> item) {
+                return item.getValue();
+            }
+        }).toString());
+    }
 }