Lambdas.

src/main/java/org/apache/commons/lang3/ArrayUtils.java

@@ -3663,7 +3663,7 @@ public static boolean isSorted(final short[] array) {
      * @since 3.4
      */
     public static <T extends Comparable<? super T>> boolean isSorted(final T[] array) {
-        return isSorted(array, (o1, o2) -> o1.compareTo(o2));
+        return isSorted(array, Comparable::compareTo);
     }
 
     /**

src/main/java/org/apache/commons/lang3/Streams.java

@@ -445,7 +445,7 @@ public ArrayCollector(final Class<O> elementType) {
 
         @Override
         public Supplier<List<O>> supplier() {
-            return () -> new ArrayList<>();
+            return ArrayList::new;
         }
 
         @Override
@@ -465,7 +465,7 @@ public BinaryOperator<List<O>> combiner() {
 
         @Override
         public Function<List<O>, O[]> finisher() {
-            return (list) -> {
+            return list -> {
                 @SuppressWarnings("unchecked")
                 final O[] array = (O[]) Array.newInstance(elementType, list.size());
                 return list.toArray(array);

src/test/java/org/apache/commons/lang3/FunctionsTest.java

@@ -152,7 +152,7 @@ void testRunnable() {
     @Test
     void testAsRunnable() {
         FailureOnOddInvocations.invocation = 0;
-        final Runnable runnable = Functions.asRunnable(() -> new FailureOnOddInvocations());
+        final Runnable runnable = Functions.asRunnable(FailureOnOddInvocations::new);
         final UndeclaredThrowableException e = assertThrows(UndeclaredThrowableException.class, () ->  runnable.run());
         final Throwable cause = e.getCause();
         assertNotNull(cause);
@@ -178,9 +178,7 @@ void testCallable() {
     @Test
     void testAsCallable() {
         FailureOnOddInvocations.invocation = 0;
-        final FailableCallable<FailureOnOddInvocations, SomeException> failableCallable = () -> {
+        final FailableCallable<FailureOnOddInvocations, SomeException> failableCallable = () -> new FailureOnOddInvocations();
-            return new FailureOnOddInvocations();
-        };
         final Callable<FailureOnOddInvocations> callable = Functions.asCallable(failableCallable);
         final UndeclaredThrowableException e = assertThrows(UndeclaredThrowableException.class, () ->  callable.call());
         final Throwable cause = e.getCause();
@@ -223,7 +221,7 @@ void testAcceptConsumer() {
     void testAsConsumer() {
         final IllegalStateException ise = new IllegalStateException();
         final Testable testable = new Testable(ise);
-        final Consumer<Testable> consumer = Functions.asConsumer((t) -> t.test());
+        final Consumer<Testable> consumer = Functions.asConsumer(t -> t.test());
         Throwable e = assertThrows(IllegalStateException.class, () -> consumer.accept(testable));
         assertSame(ise, e);
 
@@ -319,7 +317,7 @@ public void testApplyFunction() {
     public void testAsFunction() {
         final IllegalStateException ise = new IllegalStateException();
         final Testable testable = new Testable(ise);
-        final FailableFunction<Throwable, Integer, Throwable> failableFunction = (th) -> {
+        final FailableFunction<Throwable, Integer, Throwable> failableFunction = th -> {
             testable.setThrowable(th);
             return Integer.valueOf(testable.testInt());
         };
@@ -407,7 +405,7 @@ public void testGetFromSupplier() {
     @DisplayName("Test that asPredicate(FailablePredicate) is converted to -> Predicate ")
     public void testAsPredicate() {
         FailureOnOddInvocations.invocation = 0;
-        final Functions.FailablePredicate<Object, Throwable> failablePredicate = (t) -> FailureOnOddInvocations.failingBool();
+        final Functions.FailablePredicate<Object, Throwable> failablePredicate = t -> FailureOnOddInvocations.failingBool();
         final Predicate<?> predicate = Functions.asPredicate(failablePredicate);
         final UndeclaredThrowableException e = assertThrows(UndeclaredThrowableException.class, () -> predicate.test(null));
         final Throwable cause = e.getCause();
@@ -436,7 +434,7 @@ public void testAsBiPredicate() {
     @Test
     public void testAsSupplier() {
         FailureOnOddInvocations.invocation = 0;
-        final FailableSupplier<FailureOnOddInvocations, Throwable> failableSupplier = () -> new FailureOnOddInvocations();
+        final FailableSupplier<FailureOnOddInvocations, Throwable> failableSupplier = FailureOnOddInvocations::new;
         final Supplier<FailureOnOddInvocations> supplier = Functions.asSupplier(failableSupplier);
         final UndeclaredThrowableException e = assertThrows(UndeclaredThrowableException.class, () ->  supplier.get());
         final Throwable cause = e.getCause();

src/test/java/org/apache/commons/lang3/StreamsTest.java

@@ -36,7 +36,7 @@ class StreamsTest {
     @Test
     void testSimpleStreamMap() {
         final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
-        final List<Integer> output = Functions.stream(input).map((s) -> Integer.valueOf(s)).collect(Collectors.toList());
+        final List<Integer> output = Functions.stream(input).map(s -> Integer.valueOf(s)).collect(Collectors.toList());
         assertEquals(6, output.size());
         for (int i = 0;  i < 6;  i++) {
             assertEquals(i+1, output.get(i).intValue());
@@ -47,7 +47,7 @@ void testSimpleStreamMap() {
     void testSimpleStreamMapFailing() {
         final List<String> input = Arrays.asList("1", "2", "3", "4 ", "5", "6");
         try {
-            Functions.stream(input).map((s) -> Integer.valueOf(s)).collect(Collectors.toList());
+            Functions.stream(input).map(s -> Integer.valueOf(s)).collect(Collectors.toList());
             fail("Expected Exception");
         } catch (final NumberFormatException nfe) {
             assertEquals("For input string: \"4 \"", nfe.getMessage());
@@ -58,7 +58,7 @@ void testSimpleStreamMapFailing() {
     void testSimpleStreamForEach() {
         final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
         final List<Integer> output = new ArrayList<>();
-        Functions.stream(input).forEach((s) -> output.add(Integer.valueOf(s)));
+        Functions.stream(input).forEach(s -> output.add(Integer.valueOf(s)));
         assertEquals(6, output.size());
         for (int i = 0;  i < 6;  i++) {
             assertEquals(i+1, output.get(i).intValue());
@@ -76,7 +76,7 @@ void testToArray() {
     }
 
     protected <T extends Throwable> FailableConsumer<String, T> asIntConsumer(final T pThrowable) {
-        return (s) -> {
+        return s -> {
             final Integer i = Integer.valueOf(s);
             if (i.intValue() == 4) {
                 throw pThrowable;
@@ -117,8 +117,8 @@ void testSimpleStreamForEachFailing() {
     void testSimpleStreamFilter() {
         final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
         final List<Integer> output = Functions.stream(input)
-                .map((s) -> Integer.valueOf(s))
+                .map(s -> Integer.valueOf(s))
-                .filter((i) -> {
+                .filter(i -> {
                     return i.intValue() %2 == 0;
                 })
                 .collect(Collectors.toList());
@@ -133,7 +133,7 @@ private void assertEvenNumbers(final List<Integer> output) {
     }
 
     protected <T extends Throwable> FailablePredicate<Integer, T> asIntPredicate(final T pThrowable) {
-        return (i) -> {
+        return i -> {
             if (i.intValue() == 5) {
                 if (pThrowable != null) {
                     throw pThrowable;
@@ -147,7 +147,7 @@ protected <T extends Throwable> FailablePredicate<Integer, T> asIntPredicate(fin
     void testSimpleStreamFilterFailing() {
         final List<String> input = Arrays.asList("1", "2", "3", "4", "5", "6");
         final List<Integer> output = Functions.stream(input)
-                .map((s) -> Integer.valueOf(s))
+                .map(s -> Integer.valueOf(s))
                 .filter(asIntPredicate(null))
                 .collect(Collectors.toList());
         assertEvenNumbers(output);
@@ -156,7 +156,7 @@ void testSimpleStreamFilterFailing() {
         final IllegalArgumentException iae = new IllegalArgumentException("Invalid argument: " + 5);
         try {
             Functions.stream(input)
-                    .map((s) -> Integer.valueOf(s))
+                    .map(s -> Integer.valueOf(s))
                     .filter(asIntPredicate(iae))
                     .collect(Collectors.toList());
             fail("Expected Exception");
@@ -168,7 +168,7 @@ void testSimpleStreamFilterFailing() {
         final OutOfMemoryError oome = new OutOfMemoryError();
         try {
             Functions.stream(input)
-                    .map((s) -> Integer.valueOf(s))
+                    .map(s -> Integer.valueOf(s))
                     .filter(asIntPredicate(oome))
                     .collect(Collectors.toList());
             fail("Expected Exception");
@@ -180,7 +180,7 @@ void testSimpleStreamFilterFailing() {
         final SAXException se = new SAXException();
         try {
             Functions.stream(input)
-                    .map((s) -> Integer.valueOf(s))
+                    .map(s -> Integer.valueOf(s))
                     .filter(asIntPredicate(se))
                     .collect(Collectors.toList());
             fail("Expected Exception");

src/test/java/org/apache/commons/lang3/math/IEEE754rUtilsTest.java

@@ -62,7 +62,7 @@ public void testEnforceExceptions() {
 
         assertThrows(
                 IllegalArgumentException.class,
-                () -> IEEE754rUtils.min(),
+                IEEE754rUtils::min,
                 "IllegalArgumentException expected for empty input");
 
         assertThrows(
@@ -82,7 +82,7 @@ public void testEnforceExceptions() {
 
         assertThrows(
                 IllegalArgumentException.class,
-                () -> IEEE754rUtils.min(),
+                IEEE754rUtils::min,
                 "IllegalArgumentException expected for empty input");
 
         assertThrows(
@@ -92,7 +92,7 @@ public void testEnforceExceptions() {
 
         assertThrows(
                 IllegalArgumentException.class,
-                () -> IEEE754rUtils.max(),
+                IEEE754rUtils::max,
                 "IllegalArgumentException expected for empty input");
     }
 

src/test/java/org/apache/commons/lang3/math/NumberUtilsTest.java

@@ -691,7 +691,7 @@ public void testMinLong_nullArray() {
 
     @Test
     public void testMinLong_emptyArray() {
-        assertThrows(IllegalArgumentException.class, () -> NumberUtils.min());
+        assertThrows(IllegalArgumentException.class, NumberUtils::min);
     }
 
     @Test
@@ -710,7 +710,7 @@ public void testMinInt_nullArray() {
 
     @Test
     public void testMinInt_emptyArray() {
-        assertThrows(IllegalArgumentException.class, () -> NumberUtils.min());
+        assertThrows(IllegalArgumentException.class, NumberUtils::min);
     }
 
     @Test
@@ -729,7 +729,7 @@ public void testMinShort_nullArray() {
 
     @Test
     public void testMinShort_emptyArray() {
-        assertThrows(IllegalArgumentException.class, () -> NumberUtils.min());
+        assertThrows(IllegalArgumentException.class, NumberUtils::min);
     }
 
     @Test
@@ -767,7 +767,7 @@ public void testMinDouble_nullArray() {
 
     @Test
     public void testMinDouble_emptyArray() {
-        assertThrows(IllegalArgumentException.class, () -> NumberUtils.min());
+        assertThrows(IllegalArgumentException.class, NumberUtils::min);
     }
 
     @Test
@@ -786,7 +786,7 @@ public void testMinFloat_nullArray() {
 
     @Test
     public void testMinFloat_emptyArray() {
-        assertThrows(IllegalArgumentException.class, () -> NumberUtils.min());
+        assertThrows(IllegalArgumentException.class, NumberUtils::min);
     }
 
     @Test
@@ -805,7 +805,7 @@ public void testMaxLong_nullArray() {
 
     @Test
     public void testMaxLong_emptyArray() {
-        assertThrows(IllegalArgumentException.class, () -> NumberUtils.max());
+        assertThrows(IllegalArgumentException.class, NumberUtils::max);
     }
 
     @Test
@@ -824,7 +824,7 @@ public void testMaxInt_nullArray() {
 
     @Test
     public void testMaxInt_emptyArray() {
-        assertThrows(IllegalArgumentException.class, () -> NumberUtils.max());
+        assertThrows(IllegalArgumentException.class, NumberUtils::max);
     }
 
     @Test
@@ -843,7 +843,7 @@ public void testMaxShort_nullArray() {
 
     @Test
     public void testMaxShort_emptyArray() {
-        assertThrows(IllegalArgumentException.class, () -> NumberUtils.max());
+        assertThrows(IllegalArgumentException.class, NumberUtils::max);
     }
 
     @Test
@@ -881,7 +881,7 @@ public void testMaxDouble_nullArray() {
 
     @Test
     public void testMaxDouble_emptyArray() {
-        assertThrows(IllegalArgumentException.class, () -> NumberUtils.max());
+        assertThrows(IllegalArgumentException.class, NumberUtils::max);
     }
 
     @Test
@@ -892,7 +892,7 @@ public void testMaxDouble() {
 
         assertThrows(
                 IllegalArgumentException.class,
-                () -> NumberUtils.max(),
+                NumberUtils::max,
                 "No exception was thrown for empty input.");
 
         assertEquals(5.1f, NumberUtils.max(5.1f), "max(double[]) failed for array length 1");
@@ -909,7 +909,7 @@ public void testMaxFloat_nullArray() {
 
     @Test
     public void testMaxFloat_emptyArray() {
-        assertThrows(IllegalArgumentException.class, () -> NumberUtils.max());
+        assertThrows(IllegalArgumentException.class, NumberUtils::max);
     }
 
     @Test