* added examples of filtering collections using Streams, Apache CollectionUtils, Guava and Eclipse Collections

2018-07-24 00:40:13 -03:00
parent 4ee81a2fd9
commit 5b489423d8
6 changed files with 176 additions and 0 deletions
@@ -0,0 +1,46 @@
+package com.baeldung.java.filtering;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+
+import org.junit.jupiter.api.Test;
+import org.junit.platform.runner.JUnitPlatform;
+import org.junit.runner.RunWith;
+
+@RunWith(JUnitPlatform.class)
+public class CollectionFiltersUnitTest {
+
+    private static final Collection<Integer> BASE_INTEGER_COLLECTION = Arrays.asList(9, 14, 2, 7, 1, 5, 8);
+    private static final Collection<Integer> EXPECTED_EVEN_FILTERED_COLLECTION = Arrays.asList(14, 2, 8);
+
+    @Test
+    public void givenAStringCollection_whenFilteringFourLetterWords_thenObtainTheFilteredCollection() {
+        final Collection<String> baseStrings = Arrays.asList("java", "baeldung", "type", "example", "other");
+
+        Collection<String> filtered = StreamsCollectionFilter.filterCollectionHelperMethod(baseStrings, item -> item.length() == 4);
+
+        assertThat(filtered).containsExactlyInAnyOrder("java", "type");
+    }
+
+    @Test
+    public void givenAnIntegerCollection_whenFilteringEvenValues_thenObtainTheFilteredCollectionForAllCases() {
+        Collection<Integer> filteredWithStreams1 = StreamsCollectionFilter.findEvenNumbersUsingLambda(BASE_INTEGER_COLLECTION);
+        Collection<Integer> filteredWithStreams2 = StreamsCollectionFilter.findEvenNumbersUsingPredicate(BASE_INTEGER_COLLECTION);
+        Collection<Integer> filteredWithCollectionUtils = CollectionUtilsCollectionFilter.findEvenNumbers(new ArrayList<>(BASE_INTEGER_COLLECTION));
+        Collection<Integer> filteredWithEclipseCollections = EclipseCollectionsCollectionFilter.findEvenNumbers(BASE_INTEGER_COLLECTION);
+        Collection<Integer> filteredWithEclipseCollectionsUsingIterate = EclipseCollectionsCollectionFilter.findEvenNumbersUsingIterate(BASE_INTEGER_COLLECTION);
+        Collection<Integer> filteredWithGuava = GuavaCollectionFilter.findEvenNumbers(BASE_INTEGER_COLLECTION);
+
+        assertThat(filteredWithStreams1).hasSameElementsAs(filteredWithStreams2)
+            .hasSameElementsAs(filteredWithCollectionUtils)
+            .hasSameElementsAs(filteredWithEclipseCollections)
+            .hasSameElementsAs(filteredWithEclipseCollectionsUsingIterate)
+            .hasSameElementsAs(filteredWithEclipseCollectionsUsingIterate)
+            .hasSameElementsAs(filteredWithGuava)
+            .hasSameElementsAs(EXPECTED_EVEN_FILTERED_COLLECTION);
+    }
+
+}