Refactor Smatt examples (eugenp#2091)

Author: pivovarit

core-java/src/main/java/com/baeldung/string/StringToCharStream.java

@@ -2,10 +2,14 @@
 
 import org.junit.Test;
 
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 import java.util.stream.Stream;
 
 import static org.hamcrest.CoreMatchers.instanceOf;
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
@@ -16,7 +20,6 @@ public class StringToCharStreamUnitTest {
 
     @Test
     public void givenTestString_whenChars_thenReturnIntStream() {
-
         assertThat(testString.chars(), instanceOf(IntStream.class));
     }
 
@@ -25,19 +28,34 @@ public void givenTestString_whenCodePoints_thenReturnIntStream() {
         assertThat(testString.codePoints(), instanceOf(IntStream.class));
     }
 
+    @Test
+    public void givenTestString_whenCodePoints_thenShowOccurences() throws Exception {
+        Map<Character, Integer> map = testString.codePoints()
+          .mapToObj(c -> (char) c)
+          .filter(Character::isLetter)
+          .collect(Collectors.toMap(c -> c, c -> 1, Integer::sum));
+
+        System.out.println(map);
+    }
+
     @Test
     public void givenIntStream_whenMapToObj_thenReturnCharacterStream() {
-        Stream<Character> characterStream = testString.chars().mapToObj(c -> (char) c);
-        Stream<Character> characterStream1 = testString.codePoints().mapToObj(c -> (char) c);
+        Stream<Character> characterStream = testString.chars()
+          .mapToObj(c -> (char) c);
+        Stream<Character> characterStream1 = testString.codePoints()
+          .mapToObj(c -> (char) c);
+
         assertNotNull("IntStream returned by chars() did not map to Stream<Character>", characterStream);
         assertNotNull("IntStream returned by codePoints() did not map to Stream<Character>", characterStream1);
     }
 
     @Test
     public void givenIntStream_whenMapToObj_thenReturnStringStream() {
-        Stream<String> stringStream
-          = testString.codePoints().mapToObj(c -> String.valueOf((char) c));
-        assertNotNull(stringStream);
+        List<String> strings = testString.codePoints()
+          .mapToObj(c -> String.valueOf((char) c))
+          .collect(Collectors.toList());
+
+        assertEquals(strings.size(), 5);
     }
 
 }