Added additional trim methods for Strings

src/main/java/com/rometools/utils/Strings.java

@@ -48,7 +48,7 @@ public final class Strings {
     }
 
     /**
-     * null-safe trimming of a String.
+     * Removes the whitespace at the beginning and end of a String.
      *
      * @param s The String to trim, may be null
      * @return null when the input String is null, the trimmed String otherwise
@@ -61,6 +61,36 @@ public final class Strings {
         }
     }
 
+    /**
+     * Removes the whitespace at the beginning and end of a String. When the String only contains whitespace, it returns null.
+     *
+     * @param s The String to trim, may be null
+     * @return null when the input String is null or does only contain whitespace, the trimmed String otherwise
+     */
+    public static String trimToNull(final String s) {
+        final String trimmed = trim(s);
+        if (trimmed == null || trimmed.isEmpty()) {
+            return null;
+        } else {
+            return trimmed;
+        }
+    }
+
+    /**
+     * Removes the whitespace at the beginning and end of a String. When the String only contains whitespace, it returns null.
+     *
+     * @param s The String to trim, may be null
+     * @return null when the input String is null or does only contain whitespace, the trimmed String otherwise
+     */
+    public static String trimToEmpty(final String s) {
+        final String trimmed = trim(s);
+        if (trimmed == null || trimmed.isEmpty()) {
+            return "";
+        } else {
+            return trimmed;
+        }
+    }
+
     /**
      * null-safe lower-case conversion of a String.
      *

src/test/java/com/rometools/utils/StringsTest.java

@@ -80,6 +80,34 @@ public class StringsTest {
         assertThat(Strings.trim(string), is("a"));
     }
 
+    @Test
+    public void testTrimToEmpty() {
+
+        final String nullString = null;
+        final String emptyString = "";
+        final String blankString = " ";
+        final String string = " a ";
+
+        assertThat(Strings.trimToEmpty(nullString), is(""));
+        assertThat(Strings.trimToEmpty(emptyString), is(""));
+        assertThat(Strings.trimToEmpty(blankString), is(""));
+        assertThat(Strings.trimToEmpty(string), is("a"));
+    }
+
+    @Test
+    public void testTrimToNull() {
+
+        final String nullString = null;
+        final String emptyString = "";
+        final String blankString = " ";
+        final String string = " a ";
+
+        assertThat(Strings.trimToNull(nullString), is(nullValue()));
+        assertThat(Strings.trimToNull(emptyString), is(nullValue()));
+        assertThat(Strings.trimToNull(blankString), is(nullValue()));
+        assertThat(Strings.trimToNull(string), is("a"));
+    }
+
     @Test
     public void testToLowerCase() {