The String "null" will be always be passed as null object (#20).

README.md

@@ -225,8 +225,6 @@ class DataProviderTest {
 
 ### Let ```@DataProvider``` directly providing test data
 
-with a fix to handling primitive wrapper classes (like Integer) for parameters passed in the annotation and the Usage Tutorial test (line below). 
-
 Instead of using ```@UseDataProvider``` to point to a method providing test data, you can directly
 pass test data using ```@DataProvider``` annotation and its ```#value()``` method to provide an 
 array of comma-separated ```String```s. Each comma-separated ```String``` is split and trimmed back by 
@@ -235,6 +233,8 @@ resulting ```String``` is then parsed to its corresponding type in the test meth
 types (e.g. ```char```, ```boolean```, ```int```), primitive wrapper types (e.g. ```Long```, ```Double```), ```Enum```s,
 and ```String```s are supported.
 
+*Note:* The ```String``` "null" will always be passed as ```null```.
+
 ```java
     // @formatter:off
     @Test
@@ -249,8 +249,24 @@ and ```String```s are supported.
         // Expect:
         assertThat(str.length()).isEqualTo(expectedLength);
     }
+
+    @Test
+    @DataProvider({
+            "null",
+            "",
+        })
+    public void testIsEmptyString2(String str) {
+        // When:
+        boolean isEmpty = (str == null) ? true : str.isEmpty();
+
+        // Then:
+        assertThat(isEmpty).isTrue();
+    }
 ```
 
+Further examples can be found in [DataProviderJavaAcceptanceTest.java](/src/test/java/com/tngtech/test/java/junit/dataprovider/DataProviderJavaAcceptanceTest.java).
+
+
 Release notes
 -------------
 

src/main/java/com/tngtech/java/junit/dataprovider/DataProvider.java

@@ -27,7 +27,7 @@
  * {@code double}), primitive wrapper types (e.g. {@link Boolean}, {@link Long}), case-sensitive {@link Enum} values, or
  * {@link String}s. The former two are converted using the {@code valueOf(String)} methods of their corresponding
  * wrapper classes or {@code valueOf(Class<? extends Enum<?>>, String)}, respectively. This can cause {@link Exception}s
- * at runtime. Latter must not contain commas!</li>
+ * at runtime. Latter must not contain commas! The {@link String} "null" will always be passed as {@code null}.</li>
  * </ul>
  * <p>
  * Copyright by TNG Technology Consulting GmbH, Germany

src/main/java/com/tngtech/java/junit/dataprovider/DataProviderRunner.java

@@ -386,6 +386,10 @@ Object[] getParameters(String data, Class<?>[] parameterTypes, int rowIdx) {
 
     private Object convert(String str, Class<?> targetType) {
 
+        if ("null".equals(str)) {
+            return null;
+        }
+
         if (String.class.equals(targetType)) {
             return str;
         }

src/test/java/com/tngtech/java/junit/dataprovider/DataProviderRunnerTest.java

@@ -1069,7 +1069,7 @@ public void testGetParametersShouldCorrectlyParseAllPrimitiveWrapperTypes() {
         String data = "true,1,c,2,3,4,5.5,6.6";
         Class<?>[] parameterTypes = new Class[] { Boolean.class, Byte.class, Character.class, Short.class,
                 Integer.class, Long.class, Float.class, Double.class };
-        int rowIdx = 1;
+        int rowIdx = 12;
 
         // When:
         Object[] result = underTest.getParameters(data, parameterTypes, rowIdx);
@@ -1080,6 +1080,20 @@ public void testGetParametersShouldCorrectlyParseAllPrimitiveWrapperTypes() {
                         Integer.valueOf(3), Long.valueOf(4L), Float.valueOf(5.5f), Double.valueOf(6.6d) });
     }
 
+    @Test
+    public void testGetParametersShouldCorrectlyParseNullValue() {
+        // Given:
+        String data = "null, null  ";
+        Class<?>[] parameterTypes = new Class[] { Boolean.class, String.class };
+        int rowIdx = 13;
+
+        // When:
+        Object[] result = underTest.getParameters(data, parameterTypes, rowIdx);
+
+        // Then:
+        assertThat(result).isEqualTo(new Object[] { null, null });
+    }
+
     private Method getMethod(String methodName, Class<?>... args) {
         final Class<? extends DataProviderRunnerTest> clazz = this.getClass();
         try {

src/test/java/com/tngtech/test/java/junit/dataprovider/DataProviderJavaAcceptanceTest.java

@@ -188,4 +188,17 @@ public void testOldModeToRoundingMode(int oldMode, RoundingMode expected) {
         // Then:
         assertThat(result).isEqualTo(expected);
     }
+
+    @Test
+    @DataProvider({
+            "null",
+            "",
+        })
+    public void testIsEmptyString2(String str) {
+        // When:
+        boolean isEmpty = (str == null) ? true : str.isEmpty();
+
+        // Then:
+        assertThat(isEmpty).isTrue();
+    }
 }