BAEL-3022 - Converting Iterator to List (#7109)

* BAEL-3022 - Converting Iterator to List

* BAEL-3022 - Converting Iterator to List.
Removed Service Class and moved logic to Junit class

* BAEL-3022 - Converting Iterator to List
Code Formatting.

java-collections-conversions/src/test/java/com/baeldung/convertiteratortolist/ConvertIteratorToListServiceUnitTest.java

@@ -0,0 +1,100 @@
+package com.baeldung.convertiteratortolist;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.collection.IsCollectionWithSize.hasSize;
+import static org.hamcrest.collection.IsIterableContainingInAnyOrder.containsInAnyOrder;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+import org.apache.commons.collections4.IteratorUtils;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Lists;
+
+public class ConvertIteratorToListServiceUnitTest {
+
+    Iterator<Integer> iterator;
+
+    @Before
+    public void setUp() throws Exception {
+        iterator = Arrays.asList(1, 2, 3)
+            .iterator();
+    }
+
+    @Test
+    public void givenAnIterator_whenConvertIteratorToListUsingWhileLoop_thenReturnAList() {
+
+        List<Integer> actualList = new ArrayList<Integer>();
+
+        // Convert Iterator to List using while loop dsf
+        while (iterator.hasNext()) {
+            actualList.add(iterator.next());
+        }
+
+        assertThat(actualList, hasSize(3));
+        assertThat(actualList, containsInAnyOrder(1, 2, 3));
+    }
+
+    @Test
+    public void givenAnIterator_whenConvertIteratorToListAfterJava8_thenReturnAList() {
+        List<Integer> actualList = new ArrayList<Integer>();
+
+        // Convert Iterator to List using Java 8
+        iterator.forEachRemaining(actualList::add);
+
+        assertThat(actualList, hasSize(3));
+        assertThat(actualList, containsInAnyOrder(1, 2, 3));
+    }
+
+    @Test
+    public void givenAnIterator_whenConvertIteratorToListJava8Stream_thenReturnAList() {
+
+        // Convert iterator to iterable
+        Iterable<Integer> iterable = () -> iterator;
+
+        // Extract List from stream
+        List<Integer> actualList = StreamSupport
+            .stream(iterable.spliterator(), false)
+            .collect(Collectors.toList());
+
+        assertThat(actualList, hasSize(3));
+        assertThat(actualList, containsInAnyOrder(1, 2, 3));
+    }
+
+    @Test
+    public void givenAnIterator_whenConvertIteratorToImmutableListWithGuava_thenReturnAList() {
+
+        // Convert Iterator to an Immutable list using Guava library in Java
+        List<Integer> actualList = ImmutableList.copyOf(iterator);
+
+        assertThat(actualList, hasSize(3));
+        assertThat(actualList, containsInAnyOrder(1, 2, 3));
+    }
+
+    @Test
+    public void givenAnIterator_whenConvertIteratorToMutableListWithGuava_thenReturnAList() {
+
+        // Convert Iterator to a mutable list using Guava library in Java
+        List<Integer> actualList = Lists.newArrayList(iterator);
+
+        assertThat(actualList, hasSize(3));
+        assertThat(actualList, containsInAnyOrder(1, 2, 3));
+    }
+
+    @Test
+    public void givenAnIterator_whenConvertIteratorToMutableListWithApacheCommons_thenReturnAList() {
+
+        // Convert Iterator to a mutable list using Apache Commons library in Java
+        List<Integer> actualList = IteratorUtils.toList(iterator);
+
+        assertThat(actualList, hasSize(3));
+        assertThat(actualList, containsInAnyOrder(1, 2, 3));
+    }
+}