Resolved #83

src/main/java/strman/Strman.java

@@ -42,8 +42,9 @@ import static java.util.stream.Collectors.*;
  */
 public abstract class Strman {
 
-    private static final Predicate<String> NULL_STRING_PREDICATE = str -> str == null;
+    private static final Predicate<String> NULL_STRING_PREDICATE = Objects::isNull;
     private static final Supplier<String> NULL_STRING_MSG_SUPPLIER = () -> "'value' should be not null.";
+    private static final String[] EMPTY_ARRAY = new String[0];
 
     private Strman() {
     }
@@ -1333,6 +1334,19 @@ public abstract class Strman {
                 .collect(toList());
     }
 
+    /**
+     * Split lines to an array
+     *
+     * @param input The input String
+     * @return lines in an array
+     */
+    public static String[] lines(String input) {
+        if (input == null) {
+            return EMPTY_ARRAY;
+        }
+        return input.split("\r\n?|\n");
+    }
+
     private static void validate(String value, Predicate<String> predicate, final Supplier<String> supplier) {
         if (predicate.test(value)) {
             throw new IllegalArgumentException(supplier.get());

src/test/java/strman/StrmanTests.java

@@ -32,9 +32,12 @@ import org.junit.Test;
 import java.util.*;
 
 import static java.util.Arrays.asList;
+import static java.util.Collections.singletonList;
 import static java.util.stream.Collectors.toList;
 import static org.hamcrest.CoreMatchers.*;
+import static org.hamcrest.collection.IsArrayContaining.hasItemInArray;
 import static org.hamcrest.collection.IsArrayContainingInOrder.arrayContaining;
+import static org.hamcrest.collection.IsArrayWithSize.arrayWithSize;
 import static org.hamcrest.collection.IsArrayWithSize.emptyArray;
 import static org.hamcrest.collection.IsEmptyCollection.empty;
 import static org.junit.Assert.*;
@@ -1114,6 +1117,27 @@ public class StrmanTests {
     @Test
     public void zip_shouldReturnInputInListForm_whenOnlyOneInput() {
         assertThat(zip("zip"), is(equalTo(asList("z", "i", "p"))));
-        assertThat(zip("z"), is(equalTo(asList("z"))));
+        assertThat(zip("z"), is(equalTo(singletonList("z"))));
+    }
+
+    @Test
+    public void lines_shouldReturnEmptyArrayWhenInputIsNull() throws Exception {
+        assertThat(lines(null), emptyArray());
+    }
+
+    @Test
+    public void lines_shouldReturnArrayWithOneEmptyElementWhenInputIsEmptyString() throws Exception {
+        assertThat(lines(""), arrayWithSize(1));
+        assertThat(lines(""), hasItemInArray(""));
+    }
+
+    @Test
+    public void lines_shouldSplitToLines() throws Exception {
+        assertThat(lines("Hello\r\nWorld").length, equalTo(2));
+        assertThat(lines("Hello\rWorld").length, equalTo(2));
+        assertThat(lines("Hello World").length, equalTo(1));
+        assertThat(lines("\r\n\n\r ").length, equalTo(4));
+        assertThat(lines("Hello\r\r\nWorld").length, equalTo(3));
+        assertThat(lines("Hello\r\rWorld").length, equalTo(3));
     }
 }