Joining/Splitting Strings with Java and Stream API (#1130)

* rest with spark java

* 4

* Update Application.java

* indentation changes

* spring @requestmapping shortcuts

* removing spring requestmapping and pushing spring-mvc-java

* Joining/Splitting Strings with Java and Stream API

core-java/src/main/java/com/baeldung/streamApi/JoinerSplitter.java

@@ -0,0 +1,23 @@
+package com.baeldung.streamApi;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class JoinerSplitter {
+
+	public static String join ( String[] arrayOfString ) {
+		return Arrays.asList(arrayOfString)
+				.stream()
+				.map(x -> x)
+				.collect(Collectors.joining(","));
+	}
+	
+	public static List<String> split ( String str ) {
+		return Stream.of(str.split(","))
+				.map (elem -> new String(elem))
+				.collect(Collectors.toList());
+	}
+	
+}

core-java/src/test/java/com/baeldung/stream/JoinerSplitterTest.java

@@ -0,0 +1,38 @@
+package com.baeldung.stream;
+
+import static org.junit.Assert.*;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.junit.Test;
+
+import com.baeldung.streamApi.JoinerSplitter;
+
+public class JoinerSplitterTest {
+
+	@Test
+	public void provided_array_convert_to_stream_and_convert_to_string() {
+		String[] programming_languages = {"java", "python", "nodejs", "ruby"};
+		String expectation = "java,python,nodejs,ruby";
+		
+		String result  = JoinerSplitter.join(programming_languages);
+		assertEquals(result, expectation);
+	}
+	
+	@Test
+	public void provided_list_convert_to_stream_and_convert_to_list() {
+		String programming_languages = "java,python,nodejs,ruby";
+		
+		List<String> expectation = new ArrayList<String>();
+		expectation.add("java");
+		expectation.add("python");
+		expectation.add("nodejs");
+		expectation.add("ruby");
+		
+		List<String> result  = JoinerSplitter.split(programming_languages);
+		
+		assertEquals(result, expectation);
+	}
+	
+}