Do our null checking less wonkily.

git-svn-id: https://samskivert.googlecode.com/svn/trunk@2959 6335cc39-0255-0410-8fd6-9bcaacd3b74c

src/main/java/com/samskivert/util/ListUtil.java

@@ -103,9 +103,8 @@ public class ListUtil
      */
     public static Object[] add (Object[] list, int startIdx, Object element)
     {
-        if (element == null) {
-            throw NPE();
-        }
+        requireNotNull(element);
+
         // make sure we've got a list to work with
         if (list == null) {
             list = new Object[DEFAULT_LIST_SIZE];
@@ -147,9 +146,8 @@ public class ListUtil
      */
     public static Object[] insert (Object[] list, int index, Object element)
     {
-        if (element == null) {
-            throw NPE();
-        }
+        requireNotNull(element);
+
         // make sure we've got a list to work with
         if (list == null) {
             list = new Object[DEFAULT_LIST_SIZE];
@@ -215,9 +213,8 @@ public class ListUtil
     protected static Object[] testAndAdd (
         EqualityComparator eqc, Object[] list, Object element)
     {
-        if (element == null) {
-            throw NPE();
-        }
+        requireNotNull(element == null);
+
         // make sure we've got a list to work with
         if (list == null) {
             list = new Object[DEFAULT_LIST_SIZE];
@@ -327,9 +324,7 @@ public class ListUtil
     protected static int indexOf (
         EqualityComparator eqc, Object[] list, Object element)
     {
-        if (element == null) {
-            throw NPE();
-        }
+        requireNotNull(element == null);
         if (list != null) {
             for (int ii = 0, nn = list.length; ii < nn; ii++) {
                 if (eqc.equals(list[ii], element)) {
@@ -489,12 +484,13 @@ public class ListUtil
     }
 
     /**
-     * Throw a NullPointerException with the bad news.
+     * Throws a NullPointerException if the element is null.
      */
-    protected static NullPointerException NPE ()
+    protected static void requireNotNull (Object element)
     {
-        return new NullPointerException(
-            "ListUtil does not support null elements.");
+        if (element == null) {
+            throw new NullPointerException("ListUtil does not support null elements.");
+        }
     }
 
     /**