functional work

Author: Eugen Paraschiv

guava/src/test/java/org/baeldung/guava/GuavaFunctionalExamplesTest.java

@@ -1,16 +1,24 @@
 package org.baeldung.guava;
 
+import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.lessThan;
 import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
 
 import java.util.Collections;
 import java.util.List;
+import java.util.Map;
+import java.util.Set;
 
 import org.junit.Test;
 
+import com.google.common.base.Function;
 import com.google.common.base.Predicate;
 import com.google.common.collect.Collections2;
+import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
+import com.google.common.collect.Maps;
+import com.google.common.collect.Sets;
 
 public class GuavaFunctionalExamplesTest {
 
@@ -19,7 +27,7 @@ public class GuavaFunctionalExamplesTest {
     // predicates
 
     @Test
-    public final void whenFilteringStringsAccordingToACondition_thenCorrectResults() {
+    public final void whenFilteringNumbersAccordingToACondition_thenCorrectResults() {
         final List<Integer> randomNumbers = Lists.newArrayList(1, 2, 3, 6, 8, 10, 34, 57, 89);
         final Predicate<Integer> acceptEvenNumber = new Predicate<Integer>() {
             @Override
@@ -33,4 +41,38 @@ public final boolean apply(final Integer number) {
         assertThat(found, lessThan(0));
     }
 
+    @Test
+    public final void givenEvenNumbers_whenCheckingIfAllSatisfyTheEvenPredicate_thenYes() {
+        final List<Integer> eventNumbers = Lists.newArrayList(2, 6, 8, 10, 34, 90);
+        final Predicate<Integer> acceptEvenNumber = new Predicate<Integer>() {
+            @Override
+            public final boolean apply(final Integer number) {
+                return (number % 2) == 0;
+            }
+        };
+
+        assertTrue(Iterables.all(eventNumbers, acceptEvenNumber));
+    }
+
+    // Set+Function => Map
+
+    /**
+     * - see: http://code.google.com/p/guava-libraries/issues/detail?id=56
+     */
+    @Test
+    public final void whenMapIsBackedBySetAndFunction_thenCorrect() {
+        final Function<Integer, Integer> powerOfTwo = new Function<Integer, Integer>() {
+            @Override
+            public final Integer apply(final Integer input) {
+                return (int) Math.pow(input, 2);
+            }
+        };
+        final Set<Integer> lowNumbers = Sets.newHashSet(2, 3, 4);
+
+        final Map<Integer, Integer> numberToPowerOfTwoMuttable = Maps.asMap(lowNumbers, powerOfTwo);
+        final Map<Integer, Integer> numberToPowerOfTwoImuttable = Maps.toMap(lowNumbers, powerOfTwo);
+        assertThat(numberToPowerOfTwoMuttable.get(2), equalTo(4));
+        assertThat(numberToPowerOfTwoImuttable.get(2), equalTo(4));
+    }
+
 }