LANG-701 - Added new joinWith method to support varargs

src/main/java/org/apache/commons/lang3/StringUtils.java

@@ -17,7 +17,6 @@
 package org.apache.commons.lang3;
 
 import java.io.UnsupportedEncodingException;
-
 import java.nio.charset.Charset;
 import java.text.Normalizer;
 import java.util.ArrayList;
@@ -4179,6 +4178,46 @@ public static String join(final Iterable<?> iterable, final String separator) {
         return join(iterable.iterator(), separator);
     }
 
+    /**
+     * <p>Joins the elements of the provided varargs into a
+     * single String containing the provided elements.</p>
+     *
+     * <p>No delimiter is added before or after the list.
+     * {@code null} elements and separator are treated as empty Strings ("").</p>
+     *
+     * <pre>
+     * StringUtils.joinWith(",", {"a", "b"})        = "a,b"
+     * StringUtils.joinWith(",", {"a", "b",""})     = "a,b,"
+     * StringUtils.joinWith(",", {"a", null, "b"})  = "a,,b"
+     * StringUtils.joinWith(null, {"a", "b"})       = "ab"
+     * </pre>
+     *
+     * @param separator the separator character to use, null treated as ""
+     * @param objects the varargs providing the values to join together. {@code null} elements are treated as ""
+     * @return the joined String.
+     * @throws java.lang.IllegalArgumentException if a null varargs is provided
+     */
+    public static String joinWith(final String separator, Object... objects) {
+        if (objects == null) {
+            throw new IllegalArgumentException("Object varargs must not be null");
+        }
+
+        String sanitizedSeparator = defaultString(separator, StringUtils.EMPTY);
+
+        StringBuilder result = new StringBuilder();
+
+        Iterator<Object> iterator = Arrays.asList(objects).iterator();
+        while (iterator.hasNext()) {
+            result.append(ObjectUtils.toString(iterator.next()));
+
+            if (iterator.hasNext()) {
+                result.append(sanitizedSeparator);
+            }
+        }
+
+        return result.toString();
+    }
+
     // Delete
     //-----------------------------------------------------------------------
     /**

src/test/java/org/apache/commons/lang3/StringUtilsTest.java

@@ -460,6 +460,24 @@ public void testJoin_IterableString() {
         assertEquals(TEXT_LIST, StringUtils.join(Arrays.asList(ARRAY_LIST), SEPARATOR));
     }
 
+    @Test
+    public void testJoinWith() {
+        assertEquals("", StringUtils.joinWith(",", new Object[0]));        // empty array
+        assertEquals("", StringUtils.joinWith(",", NULL_ARRAY_LIST));
+        assertEquals("null", StringUtils.joinWith(",", NULL_TO_STRING_LIST));   //toString method prints 'null'
+
+        assertEquals("a,b,c", StringUtils.joinWith(",", new String[]{"a", "b", "c"}));
+        assertEquals(",a,", StringUtils.joinWith(",", new String[]{null, "a", ""}));
+
+        assertEquals("ab", StringUtils.joinWith(null, "a", "b"));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testJoinWithThrowsException() {
+        StringUtils.joinWith(",", null);
+    }
+
+
     @Test
     public void testSplit_String() {
         assertNull(StringUtils.split(null));