[LANG-1556] Use Java 8 lambdas and Map operations. (#541)

* java8

* refine

* rebase

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

@@ -450,9 +450,7 @@ public class Streams {
 
         @Override
         public BiConsumer<List<O>, O> accumulator() {
-            return (list, o) -> {
+            return List::add;
-                list.add(o);
-            };
         }
 
         @Override

src/main/java/org/apache/commons/lang3/concurrent/TimedSemaphore.java

@@ -417,7 +417,7 @@ public class TimedSemaphore {
      * @return a future object representing the task scheduled
      */
     protected ScheduledFuture<?> startTimer() {
-        return getExecutorService().scheduleAtFixedRate(() -> endOfPeriod(), getPeriod(), getPeriod(), getUnit());
+        return getExecutorService().scheduleAtFixedRate(this::endOfPeriod, getPeriod(), getPeriod(), getUnit());
     }
 
     /**

src/main/java/org/apache/commons/lang3/exception/DefaultExceptionContext.java

@@ -19,7 +19,6 @@ package org.apache.commons.lang3.exception;
 import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.HashSet;
-import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
 
@@ -60,12 +59,7 @@ public class DefaultExceptionContext implements ExceptionContext, Serializable {
      */
     @Override
     public DefaultExceptionContext setContextValue(final String label, final Object value) {
-        for (final Iterator<Pair<String, Object>> iter = contextValues.iterator(); iter.hasNext();) {
+        contextValues.removeIf(p -> StringUtils.equals(label, p.getKey()));
-            final Pair<String, Object> p = iter.next();
-            if (StringUtils.equals(label, p.getKey())) {
-                iter.remove();
-            }
-        }
         addContextValue(label, value);
         return this;
     }

src/main/java/org/apache/commons/lang3/reflect/MethodUtils.java

@@ -60,7 +60,7 @@ import org.apache.commons.lang3.Validate;
  */
 public class MethodUtils {
 
-    private static final Comparator<Method> METHOD_BY_SIGNATURE = (m1, m2) -> m1.toString().compareTo(m2.toString());
+    private static final Comparator<Method> METHOD_BY_SIGNATURE = Comparator.comparing(Method::toString);
 
     /**
      * <p>{@link MethodUtils} instances should NOT be constructed in standard programming.

src/main/java/org/apache/commons/lang3/reflect/TypeUtils.java

@@ -875,8 +875,10 @@ public class TypeUtils {
         // map the arguments to their respective type variables
         for (int i = 0; i < typeParams.length; i++) {
             final Type typeArg = typeArgs[i];
-            typeVarAssigns.put(typeParams[i], typeVarAssigns.containsKey(typeArg) ? typeVarAssigns
+            typeVarAssigns.put(
-                    .get(typeArg) : typeArg);
+                    typeParams[i],
+                    typeVarAssigns.getOrDefault(typeArg, typeArg)
+            );
         }
 
         if (toClass.equals(cls)) {

src/main/java/org/apache/commons/lang3/time/FastDateParser.java

@@ -94,7 +94,7 @@ public class FastDateParser implements DateParser, Serializable {
     // comparator used to sort regex alternatives
     // alternatives should be ordered longer first, and shorter last. ('february' before 'feb')
     // all entries must be lowercase by locale.
-    private static final Comparator<String> LONGER_FIRST_LOWERCASE = (left, right) -> right.compareTo(left);
+    private static final Comparator<String> LONGER_FIRST_LOWERCASE = Comparator.reverseOrder();
 
     /**
      * <p>Constructs a new FastDateParser.</p>

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

@@ -1499,7 +1499,7 @@ public class ArrayUtilsTest {
 
     @Test
     public void testIsSortedComparator() {
-        final Comparator<Integer> c = (o1, o2) -> o2.compareTo(o1);
+        final Comparator<Integer> c = Comparator.reverseOrder();
 
         Integer[] array = null;
         assertTrue(ArrayUtils.isSorted(array, c));

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

@@ -579,7 +579,7 @@ class FunctionsTest {
         FailureOnOddInvocations.invocations = 0;
         final FailableCallable<FailureOnOddInvocations, SomeException> failableCallable = FailureOnOddInvocations::new;
         final Callable<FailureOnOddInvocations> callable = Functions.asCallable(failableCallable);
-        final UndeclaredThrowableException e = assertThrows(UndeclaredThrowableException.class, () ->  callable.call());
+        final UndeclaredThrowableException e = assertThrows(UndeclaredThrowableException.class, callable::call);
         final Throwable cause = e.getCause();
         assertNotNull(cause);
         assertTrue(cause instanceof SomeException);
@@ -663,7 +663,7 @@ class FunctionsTest {
     void testAsRunnable() {
         FailureOnOddInvocations.invocations = 0;
         final Runnable runnable = Functions.asRunnable(FailureOnOddInvocations::new);
-        final UndeclaredThrowableException e = assertThrows(UndeclaredThrowableException.class, () ->  runnable.run());
+        final UndeclaredThrowableException e = assertThrows(UndeclaredThrowableException.class, runnable::run);
         final Throwable cause = e.getCause();
         assertNotNull(cause);
         assertTrue(cause instanceof SomeException);
@@ -678,7 +678,7 @@ class FunctionsTest {
         FailureOnOddInvocations.invocations = 0;
         final FailableSupplier<FailureOnOddInvocations, Throwable> failableSupplier = FailureOnOddInvocations::new;
         final Supplier<FailureOnOddInvocations> supplier = Functions.asSupplier(failableSupplier);
-        final UndeclaredThrowableException e = assertThrows(UndeclaredThrowableException.class, () ->  supplier.get());
+        final UndeclaredThrowableException e = assertThrows(UndeclaredThrowableException.class, supplier::get);
         final Throwable cause = e.getCause();
         assertNotNull(cause);
         assertTrue(cause instanceof SomeException);