Add handling for UUID

refs #9

Author: patrickfav

CHANGELOG

@@ -4,6 +4,7 @@
 
  * add `encodeCharsetToBytes()` feature #7
  * add new `from(char[] charArray, Charset charset)` constructor with improved logic #8
+ * add constructor/converter from/to UUID #9
 
 ## v0.5.0
 

src/main/java/at/favre/lib/bytes/Bytes.java

@@ -21,7 +21,11 @@
 
 package at.favre.lib.bytes;
 
-import java.io.*;
+import java.io.ByteArrayInputStream;
+import java.io.DataInput;
+import java.io.File;
+import java.io.InputStream;
+import java.io.Serializable;
 import java.math.BigInteger;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
@@ -31,7 +35,14 @@
 import java.nio.charset.StandardCharsets;
 import java.security.SecureRandom;
 import java.text.Normalizer;
-import java.util.*;
+import java.util.Arrays;
+import java.util.BitSet;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Objects;
+import java.util.Random;
+import java.util.UUID;
 
 /**
  * Bytes is wrapper class for an byte-array that allows a lot of convenience operations on it:
@@ -471,6 +482,18 @@ public static Bytes from(char[] charArray, Charset charset) {
         return from(bytes);
     }
 
+    /**
+     * Convert UUID to a newly generated 16 byte long array representation. Puts the 8 byte most significant bits and
+     * 8 byte least significant bits into an byte array.
+     *
+     * @param uuid to convert to array
+     * @return new instance
+     */
+    public static Bytes from(UUID uuid) {
+        Objects.requireNonNull(uuid);
+        return wrap(Util.getBytesFromUUID(uuid).array());
+    }
+
     /**
      * Parses a big endian binary string (e.g. <code>10010001</code>)
      *
@@ -1498,6 +1521,21 @@ public BigInteger toBigInteger() {
         }
     }
 
+    /**
+     * Creates a {@link UUID} instance of the internal byte array. This requires the internal array to be exactly 16 bytes. Takes the first
+     * 8 byte as mostSigBits and the last 8 byte as leastSigBits. There is no validation of version/type, just passes the raw bytes
+     * to a {@link UUID} constructor.
+     *
+     * @return newly created UUID
+     */
+    public UUID toUUID() {
+        if (length() != 16) {
+            throw new IllegalStateException("creating UUID requires internal array to be exactly 16 bytes, was " + length());
+        }
+        ByteBuffer byteBuffer = buffer();
+        return new UUID(byteBuffer.getLong(), byteBuffer.getLong());
+    }
+
     /**
      * If the underlying byte array is exactly 1 byte / 8 bit long, returns signed two-complement
      * representation for a Java byte value.

src/main/java/at/favre/lib/bytes/Util.java

@@ -21,10 +21,23 @@
 
 package at.favre.lib.bytes;
 
-import java.io.*;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInput;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
 import java.nio.ByteBuffer;
 import java.nio.file.Files;
-import java.util.*;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.Objects;
+import java.util.Random;
+import java.util.UUID;
 
 /**
  * Common Util methods to convert or modify byte arrays
@@ -446,6 +459,20 @@ static boolean constantTimeEquals(byte[] obj, byte[] anotherArray) {
         return result == 0;
     }
 
+    /**
+     * Convert UUID to a newly generated 16 byte long array representation. Puts the 8 byte most significant bits and
+     * 8 byte least significant bits into an byte array.
+     *
+     * @param uuid to convert to array
+     * @return buffer containing the 16 bytes
+     */
+    static ByteBuffer getBytesFromUUID(UUID uuid) {
+        ByteBuffer bb = ByteBuffer.allocate(16);
+        bb.putLong(uuid.getMostSignificantBits());
+        bb.putLong(uuid.getLeastSignificantBits());
+        return bb;
+    }
+
     /*
     =================================================================================================
      Copyright 2011 Twitter, Inc.

src/test/java/at/favre/lib/bytes/BytesConstructorTests.java

@@ -38,6 +38,7 @@
 import java.util.Arrays;
 import java.util.BitSet;
 import java.util.LinkedList;
+import java.util.UUID;
 
 import static org.junit.Assert.*;
 
@@ -423,4 +424,23 @@ public void fromObjectArray() {
         Bytes b = Bytes.from(objectArray);
         assertArrayEquals(new byte[]{0x01, 0x02, 0x03, 0x04}, b.array());
     }
+
+    @Test
+    public void fromUUID() {
+        testUUID(UUID.fromString("00000000-0000-0000-0000-000000000000"));
+        testUUID(UUID.fromString("123e4567-e89b-42d3-a456-556642440000"));
+        testUUID(UUID.fromString("e8e3db08-dc39-48ea-a3db-08dc3958eafb"));
+        testUUID(UUID.randomUUID());
+    }
+
+    private void testUUID(UUID uuid) {
+        Bytes b = Bytes.from(uuid);
+        assertEquals(16, b.length());
+        assertEquals(uuid, b.toUUID());
+    }
+
+    @Test(expected = NullPointerException.class)
+    public void fromUUIDNullArgument() {
+        Bytes.from((UUID) null);
+    }
 }

src/test/java/at/favre/lib/bytes/BytesToConvertOtherTypesTest.java

@@ -219,4 +219,19 @@ public void toDouble() {
         } catch (IllegalStateException ignored) {
         }
     }
-}
+
+    @Test(expected = IllegalStateException.class)
+    public void testToUUIDToLong() {
+        Bytes.random(17).toUUID();
+    }
+
+    @Test(expected = IllegalStateException.class)
+    public void testToUUIDToShort() {
+        Bytes.random(15).toUUID();
+    }
+
+    @Test(expected = IllegalStateException.class)
+    public void testToUUIDEmpty() {
+        Bytes.allocate(0).toUUID();
+    }
+}