BAEL-885 - How to merge two Java streams? (#1884)

Added examples using: * JDK8 * StreamEx library * JOOl library
2017-05-29 10:30:25 +02:00
parent 994ac4ddbf
commit b135086d07
4 changed files with 149 additions and 0 deletions
@@ -0,0 +1,51 @@
+package com.baeldung.stream;
+
+import one.util.streamex.StreamEx;
+import org.junit.Test;
+
+import java.util.Arrays;
+
+import static org.junit.Assert.assertEquals;
+
+public class StreamExMergeStreamsTest {
+
+    @Test
+    public void givenTwoStreams_whenMergingStreams_thenResultingStreamContainsElementsFromBothStreams() {
+        StreamEx<Integer> stream1 = StreamEx.of(1, 3, 5);
+        StreamEx<Integer> stream2 = StreamEx.of(2, 4, 6);
+
+        StreamEx<Integer> resultingStream = stream1.append(stream2);
+
+        assertEquals(Arrays.asList(1, 3, 5, 2, 4, 6),
+                     resultingStream.toList());
+    }
+
+    @Test
+    public void givenFourStreams_whenMergingStreams_thenResultingStreamContainsElementsFromAllStreams() {
+        StreamEx<Integer> stream1 = StreamEx.of(1, 3, 5);
+        StreamEx<Integer> stream2 = StreamEx.of(2, 4, 6);
+        StreamEx<Integer> stream3 = StreamEx.of(18, 15, 36);
+        StreamEx<Integer> stream4 = StreamEx.of(99);
+
+        StreamEx<Integer> resultingStream = stream1.append(stream2)
+                                                   .append(stream3)
+                                                   .append(stream4);
+
+        assertEquals(Arrays.asList(1, 3, 5, 2, 4, 6, 18, 15, 36, 99),
+                     resultingStream.toList());
+
+    }
+
+    @Test
+    public void givenThreeStreams_whenAppendingAndPrependingStreams_thenResultingStreamContainsElementsFromAllStreams() {
+        StreamEx<String> stream1 = StreamEx.of("foo", "bar");
+        StreamEx<String> openingBracketStream = StreamEx.of("[");
+        StreamEx<String> closingBracketStream = StreamEx.of("]");
+
+        StreamEx<String> resultingStream = stream1.append(closingBracketStream)
+                                                  .prepend(openingBracketStream);
+
+        assertEquals(Arrays.asList("[", "foo", "bar", "]"),
+                     resultingStream.toList());
+    }
+}