Merge pull request #10636 from wnoizumi/BAEL-4877

code samples for issue BAEL-4877

core-java-modules/core-java-streams-3/src/main/java/com/baeldung/streams/conversion/EnumerationSpliterator.java

@@ -0,0 +1,30 @@
+package com.baeldung.streams.conversion;
+
+import java.util.Enumeration;
+import java.util.Spliterators.AbstractSpliterator;
+import java.util.function.Consumer;
+
+public class EnumerationSpliterator<T> extends AbstractSpliterator<T> {
+
+    private final Enumeration<T> enumeration;
+
+    public EnumerationSpliterator(long est, int additionalCharacteristics, Enumeration<T> enumeration) {
+        super(est, additionalCharacteristics);
+        this.enumeration = enumeration;
+    }
+
+    @Override
+    public boolean tryAdvance(Consumer<? super T> action) {
+        if (enumeration.hasMoreElements()) {
+            action.accept(enumeration.nextElement());
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public void forEachRemaining(Consumer<? super T> action) {
+        while (enumeration.hasMoreElements())
+            action.accept(enumeration.nextElement());
+    }
+}

core-java-modules/core-java-streams-3/src/main/java/com/baeldung/streams/conversion/EnumerationStreamConversion.java

@@ -0,0 +1,16 @@
+package com.baeldung.streams.conversion;
+
+import java.util.Enumeration;
+import java.util.Spliterator;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
+public class EnumerationStreamConversion {
+
+    public static <T> Stream<T> convert(Enumeration<T> enumeration) {
+        EnumerationSpliterator<T> spliterator = new EnumerationSpliterator<T>(Long.MAX_VALUE, Spliterator.ORDERED, enumeration);
+        Stream<T> stream = StreamSupport.stream(spliterator, false);
+
+        return stream;
+    }
+}

core-java-modules/core-java-streams-3/src/test/java/com/baeldung/streams/conversion/EnumerationStreamConversionUnitTest.java

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+package com.baeldung.streams.conversion;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.collection.IsIterableContainingInOrder.contains;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Vector;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.junit.Assert;
+import org.junit.jupiter.api.Test;
+
+public class EnumerationStreamConversionUnitTest {
+
+    @Test
+    public void givenEnumeration_whenConvertedToStream_thenNotNull() {
+        Vector<Integer> input = new Vector<>(Arrays.asList(1, 2, 3, 4, 5));
+
+        Stream<Integer> resultingStream = EnumerationStreamConversion.convert(input.elements());
+
+        Assert.assertNotNull(resultingStream);
+    }
+
+    @Test
+    public void whenConvertedToList_thenCorrect() {
+        Vector<Integer> input = new Vector<>(Arrays.asList(1, 2, 3, 4, 5));
+
+        Stream<Integer> stream = EnumerationStreamConversion.convert(input.elements());
+        List<Integer> list = stream.filter(e -> e >= 3)
+            .collect(Collectors.toList());
+        assertThat(list, contains(3, 4, 5));
+    }
+}