Fix #57: Add UUIDUtil.maxUUID() (and nilUUID()) (#64)

Author: cowtowncoder

release-notes/VERSION

@@ -4,13 +4,14 @@ Project: java-uuid-generator
 Releases
 ============================================================================
 
-4.1.0 (not yet released)
+4.1.0 (07-Jan-2023)
 
 #41: Add support for Proposed type v6 (reordered timestamp)
  (contributed by Hal H)
 #46: Add support for Proposed type v7 (epoch-based time uuid)
  (contributed by Hal H)
 #55: Add `Main-Class` manifest to make jar invoke `Jug` class
+#57: Add constants for "Nil UUID", "Max UUID" (from draft "new UUID" spec) in `UUIDUtil`
 - Fix a minor issue with argument validation for `Jug` tool class
 - Update junit dependency (via oss-parent:41)
 - Update slf4j-api to 1.7.36

src/main/java/com/fasterxml/uuid/impl/UUIDUtil.java

@@ -16,7 +16,17 @@ public class UUIDUtil
     // similarly, clock sequence and variant are multiplexed
     public final static int BYTE_OFFSET_CLOCK_SEQUENCE = 8;
     public final static int BYTE_OFFSET_VARIATION = 8;
-	
+
+    /**
+     * @since 4.1
+     */
+    private final static UUID NIL_UUID = new UUID(0L, 0L);
+
+    /**
+     * @since 4.1
+     */
+    private final static UUID MAX_UUID = new UUID(-1L, -1L);
+
     /*
     /**********************************************************************
     /* Construction (can instantiate, although usually not necessary)
@@ -27,6 +37,38 @@ public class UUIDUtil
     // via static methods
     public UUIDUtil() { }
 
+    /*
+    /**********************************************************************
+    /* Static UUID instances
+    /**********************************************************************
+     */
+
+    /**
+     * Accessor for so-call "Nil UUID" (see
+     * <a href="https://www.rfc-editor.org/rfc/rfc4122#section-4.1.7">RFC 4122/4.1.7</a>;
+     * one that is all zeroes.
+     *
+     * @since 4.1
+     *
+     * @return "Nil" UUID instance
+     */
+    public static UUID nilUUID() {
+        return NIL_UUID;
+    }
+
+    /**
+     * Accessor for so-call "Max UUID" (see
+     * <a href="https://www.ietf.org/archive/id/draft-peabody-dispatch-new-uuid-format-04.html#name-max-uuid">UUID 6 draft</a>;
+     * one that is all one bits
+     *
+     * @since 4.1
+     *
+     * @return "Nil" UUID instance
+     */
+    public static UUID maxUUID() {
+        return MAX_UUID;
+    }
+
     /*
     /**********************************************************************
     /* Factory methods

src/test/java/com/fasterxml/uuid/UUIDTest.java

@@ -34,7 +34,7 @@
  */
 public class UUIDTest extends TestCase
 {
-    final static UUID nullUUID = new UUID(0L, 0L);
+    final static UUID nullUUID = UUIDUtil.nilUUID();
 
     public UUIDTest(java.lang.String testName)
     {
@@ -51,10 +51,11 @@ public static void main(String[] args)
     {
         TestRunner.run(suite());
     }
-    
+
     /**************************************************************************
      * Begin constructor tests
      *************************************************************************/
+
     /**
      * Test of UUID() constructor, of class com.fasterxml.uuid.UUID.
      */

src/test/java/com/fasterxml/uuid/impl/UUIDUtilTest.java

@@ -0,0 +1,29 @@
+package com.fasterxml.uuid.impl;
+
+import java.util.UUID;
+
+import junit.framework.TestCase;
+
+/**
+ * Test class focusing on verifying functionality provided by
+ * {@link UUIDUtil}.
+ *<p>
+ * NOTE: some of {@code UUIDUtil} testing is via main
+ * {@link com.fasterxml.uuid.UUIDTest}.
+ */
+public class UUIDUtilTest extends TestCase
+{
+    public void testNilUUID() {
+        UUID nil = UUIDUtil.nilUUID();
+        // Should be all zeroes:
+        assertEquals(0L, nil.getMostSignificantBits());
+        assertEquals(0L, nil.getLeastSignificantBits());
+    }
+
+    public void testMaxUUID() {
+        UUID max = UUIDUtil.maxUUID();
+        // Should be all ones:
+        assertEquals(~0, max.getMostSignificantBits());
+        assertEquals(~0, max.getLeastSignificantBits());
+    }
+}