iterable to collection

java-collections-conversions/src/test/java/org/baeldung/java/collections/IterableToCollectionUnitTest.java

@@ -0,0 +1,122 @@
+package org.baeldung.java.collections;
+
+import static org.hamcrest.Matchers.contains;
+import static org.junit.Assert.assertThat;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Spliterator;
+import java.util.Spliterators;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
+
+import org.apache.commons.collections4.IterableUtils;
+import org.apache.commons.collections4.IteratorUtils;
+import org.junit.Test;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Lists;
+
+public class IterableToCollectionUnitTest {
+
+    Iterable<String> iterable = Arrays.asList("john", "tom", "jane");
+    Iterator<String> iterator = iterable.iterator();
+
+    @Test
+    public void whenConvertIterableToListUsingJava_thenSuccess() {
+        List<String> result = new ArrayList<String>();
+        for (String str : iterable) {
+            result.add(str);
+        }
+
+        assertThat(result, contains("john", "tom", "jane"));
+    }
+
+    @Test
+    public void whenConvertIterableToListUsingJava8_thenSuccess() {
+        List<String> result = new ArrayList<String>();
+        iterable.forEach(result::add);
+
+        assertThat(result, contains("john", "tom", "jane"));
+    }
+
+    @Test
+    public void whenConvertIterableToListUsingJava8WithSpliterator_thenSuccess() {
+        List<String> result = StreamSupport.stream(iterable.spliterator(), false)
+            .collect(Collectors.toList());
+
+        assertThat(result, contains("john", "tom", "jane"));
+    }
+
+    @Test
+    public void whenConvertIterableToListUsingGuava_thenSuccess() {
+        List<String> result = Lists.newArrayList(iterable);
+
+        assertThat(result, contains("john", "tom", "jane"));
+    }
+
+    @Test
+    public void whenConvertIterableToImmutableListUsingGuava_thenSuccess() {
+        List<String> result = ImmutableList.copyOf(iterable);
+
+        assertThat(result, contains("john", "tom", "jane"));
+    }
+
+    @Test
+    public void whenConvertIterableToListUsingApacheCommons_thenSuccess() {
+        List<String> result = IterableUtils.toList(iterable);
+
+        assertThat(result, contains("john", "tom", "jane"));
+    }
+
+    // ======================== Iterator
+
+    @Test
+    public void whenConvertIteratorToListUsingJava_thenSuccess() {
+        List<String> result = new ArrayList<String>();
+        while (iterator.hasNext()) {
+            result.add(iterator.next());
+        }
+
+        assertThat(result, contains("john", "tom", "jane"));
+    }
+
+    @Test
+    public void whenConvertIteratorToListUsingJava8_thenSuccess() {
+        List<String> result = new ArrayList<String>();
+        iterator.forEachRemaining(result::add);
+
+        assertThat(result, contains("john", "tom", "jane"));
+    }
+
+    @Test
+    public void whenConvertIteratorToListUsingJava8WithSpliterator_thenSuccess() {
+        List<String> result = StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator, Spliterator.ORDERED), false)
+            .collect(Collectors.toList());
+
+        assertThat(result, contains("john", "tom", "jane"));
+    }
+
+    @Test
+    public void whenConvertIteratorToListUsingGuava_thenSuccess() {
+        List<String> result = Lists.newArrayList(iterator);
+
+        assertThat(result, contains("john", "tom", "jane"));
+    }
+
+    @Test
+    public void whenConvertIteratorToImmutableListUsingGuava_thenSuccess() {
+        List<String> result = ImmutableList.copyOf(iterator);
+
+        assertThat(result, contains("john", "tom", "jane"));
+    }
+
+    @Test
+    public void whenConvertIteratorToListUsingApacheCommons_thenSuccess() {
+        List<String> result = IteratorUtils.toList(iterator);
+
+        assertThat(result, contains("john", "tom", "jane"));
+    }
+}