src/share/classes/java/util/Objects.java

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 2009, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2009, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this

@@ -23,10 +23,12 @@
  * questions.
  */
 
 package java.util;
 
+import java.util.function.Supplier;
+
 /**
  * This class consists of {@code static} utility methods for operating
  * on objects.  These utilities include {@code null}-safe or {@code
  * null}-tolerant methods for computing the hash code of an object,
  * returning a string for an object, and comparing two objects.

@@ -224,6 +226,32 @@
     public static <T> T requireNonNull(T obj, String message) {
         if (obj == null)
             throw new NullPointerException(message);
         return obj;
     }
+
+    /**
+     * Checks that the specified object reference is not {@code null} and
+     * throws a customized {@link NullPointerException} if it is.
+     *
+     * <p>Unlike the method {@link requireNonNull(Object, String},
+     * this method allows creation of the message to be deferred until
+     * after the null check is made. While this may confer a
+     * performance advantage in the non-null case, when deciding to
+     * call this method care should be taken that the costs of
+     * creating the message supplier are less than the cost of just
+     * creating the string message directly.
+     *
+     * @param obj     the object reference to check for nullity
+     * @param messageSupplier supplier of the detail message to be
+     * used in the event that a {@code NullPointerException} is thrown
+     * @param <T> the type of the reference
+     * @return {@code obj} if not {@code null}
+     * @throws NullPointerException if {@code obj} is {@code null}
+     * @since 1.8
+     */
+    public static <T> T requireNonNull(T obj, Supplier<String> messageSupplier) {
+        if (obj == null)
+            throw new NullPointerException(messageSupplier.get());
+        return obj;
+    }
 }