Improve code quality

Remove code flaws detected by PMD.

PMD Rules:

* UnnecessaryModifier
* DCN_NULLPOINTER_EXCEPTION
* DMI_RANDOM_USED_ONLY_ONCE
* EmptyCatchBlock
* RCN_REDUNDANT_NULLCHECK_WOULD_HAVE_BEEN_A_NPE

src/main/java/com/github/f4b6a3/uuid/codec/UuidCodec.java

@@ -49,7 +49,7 @@ public interface UuidCodec<T> {
 	 * @return a generic type
 	 * @throws InvalidUuidException if the argument is invalid
 	 */
-	public T encode(UUID uuid);
+	T encode(UUID uuid);
 
 	/**
 	 * Get a UUID from a generic type.
@@ -58,5 +58,5 @@ public interface UuidCodec<T> {
 	 * @return a UUID
 	 * @throws InvalidUuidException if the argument is invalid
 	 */
-	public UUID decode(T type);
+	UUID decode(T type);
 }

src/main/java/com/github/f4b6a3/uuid/codec/base/BaseNCodec.java

@@ -71,7 +71,7 @@ public abstract class BaseNCodec implements UuidCodec<String> {
 	 * }</pre>
 	 */
 	@FunctionalInterface
-	public static interface CustomDivider {
+	public interface CustomDivider {
 		/**
 		 * Divide a number by x.
 		 * 
@@ -80,7 +80,7 @@ public static interface CustomDivider {
 		 * @param x the divisor
 		 * @return a pair of longs
 		 */
-		public long[] divide(long x);
+		long[] divide(long x);
 	}
 
 	/**

src/main/java/com/github/f4b6a3/uuid/factory/AbstRandomBasedFactory.java

@@ -170,22 +170,22 @@ public B withRandomFunction(LongSupplier randomFunction) {
 	/**
 	 * Interface for random generator.
 	 */
-	protected static interface IRandom {
+	protected interface IRandom {
 
 		/**
 		 * Return a random number.
 		 * 
 		 * @return a number
 		 */
-		public long nextLong();
+		long nextLong();
 
 		/**
 		 * Return a random array of bytes.
 		 * 
 		 * @param length the length
 		 * @return an array
 		 */
-		public byte[] nextBytes(int length);
+		byte[] nextBytes(int length);
 	}
 
 	/**

src/main/java/com/github/f4b6a3/uuid/factory/function/ClockSeqFunction.java

@@ -50,7 +50,7 @@ public interface ClockSeqFunction extends LongUnaryOperator {
 	 * 
 	 * @return a number in the range 0 to 16383 (2^14-1)
 	 */
-	public static long getRandom() {
+	static long getRandom() {
 		return toExpectedRange(RandomUtil.newSecureRandom().nextLong());
 	}
 
@@ -63,7 +63,7 @@ public static long getRandom() {
 	 * @param clockseq a clock sequence
 	 * @return a number in the range 0 to 16383 (2^14-1).
 	 */
-	public static long toExpectedRange(final long clockseq) {
+	static long toExpectedRange(final long clockseq) {
 		return clockseq & 0x0000000000003fffL;
 	}
 }

src/main/java/com/github/f4b6a3/uuid/factory/function/NodeIdFunction.java

@@ -47,7 +47,7 @@ public interface NodeIdFunction extends LongSupplier {
 	 * 
 	 * @return a number in the range 0 to 2^48-1.
 	 */
-	public static long getRandom() {
+	static long getRandom() {
 		return toExpectedRange(RandomUtil.newSecureRandom().nextLong());
 	}
 
@@ -56,7 +56,7 @@ public static long getRandom() {
 	 * 
 	 * @return a number in the range 0 to 2^48-1.
 	 */
-	public static long getMulticastRandom() {
+	static long getMulticastRandom() {
 		return toMulticast(getRandom());
 	}
 
@@ -69,7 +69,7 @@ public static long getMulticastRandom() {
 	 * @param nodeid the node identifier
 	 * @return a number in the range 0 to 2^48-1.
 	 */
-	public static long toExpectedRange(final long nodeid) {
+	static long toExpectedRange(final long nodeid) {
 		return nodeid & 0x0000_ffffffffffffL;
 	}
 
@@ -82,7 +82,7 @@ public static long toExpectedRange(final long nodeid) {
 	 * @param nodeid the node identifier
 	 * @return a node identifier with the multicast bit set
 	 */
-	public static long toMulticast(long nodeid) {
+	static long toMulticast(long nodeid) {
 		return (nodeid & 0x0000_ffffffffffffL) | 0x0000_010000000000L;
 	}
 
@@ -92,7 +92,7 @@ public static long toMulticast(long nodeid) {
 	 * @param nodeid a node identifier
 	 * @return true if the node identifier is multicast
 	 */
-	public static boolean isMulticast(long nodeid) {
+	static boolean isMulticast(long nodeid) {
 		return (nodeid & 0x0000_010000000000L) == 0x0000_010000000000L;
 	}
 }

src/main/java/com/github/f4b6a3/uuid/factory/function/TimeFunction.java

@@ -60,7 +60,7 @@ public interface TimeFunction extends LongSupplier {
 	 * @param instant an instant
 	 * @return a number of 100-nanoseconds since 1970-01-01 (Unix epoch)
 	 */
-	public static long toUnixTimestamp(final Instant instant) {
+	static long toUnixTimestamp(final Instant instant) {
 		return UuidTime.toUnixTimestamp(instant);
 	}
 
@@ -73,7 +73,7 @@ public static long toUnixTimestamp(final Instant instant) {
 	 * @param timestamp a number of 100-nanoseconds since 1970-01-01 (Unix epoch)
 	 * @return a number in the range 0 to 2^60-1.
 	 */
-	public static long toExpectedRange(final long timestamp) {
+	static long toExpectedRange(final long timestamp) {
 		return timestamp & 0x0_fffffffffffffffL;
 	}
 }

src/main/java/com/github/f4b6a3/uuid/factory/function/impl/MacNodeIdFunction.java

@@ -65,7 +65,7 @@ private long getHardwareAddress() {
 				return toNumber(nic.getHardwareAddress());
 			}
 		} catch (SocketException e) {
-			// do nothing
+			return NodeIdFunction.getMulticastRandom();
 		}
 
 		return NodeIdFunction.getMulticastRandom();

src/main/java/com/github/f4b6a3/uuid/factory/standard/DceSecurityFactory.java

@@ -55,7 +55,7 @@ public DceSecurityFactory() {
 
 	private DceSecurityFactory(Builder builder) {
 		super(UuidVersion.VERSION_DCE_SECURITY, builder);
-		this.localDomain = builder != null ? builder.localDomain : 0;
+		this.localDomain = builder.localDomain;
 		this.counter = new AtomicInteger();
 	}
 

src/main/java/com/github/f4b6a3/uuid/util/internal/JavaVersionUtil.java

@@ -48,7 +48,7 @@ public static int getJavaVersion() {
                 return 8;
             }
 
-        } catch (NullPointerException | NumberFormatException | IndexOutOfBoundsException e) {
+        } catch (NumberFormatException | IndexOutOfBoundsException e) {
             return 8;
         }
     }

src/main/java/com/github/f4b6a3/uuid/util/internal/NetworkUtil.java

@@ -80,8 +80,8 @@ public static synchronized String hostname() {
 			if (hostname != null && !hostname.isEmpty()) {
 				return hostname;
 			}
-		} catch (UnknownHostException | NullPointerException e) {
-			// do nothing
+		} catch (UnknownHostException e) {
+			return null;
 		}
 
 		// not found
@@ -113,7 +113,7 @@ public static synchronized String mac(NetworkInterface nic) {
 				return mac;
 			}
 		} catch (SocketException | NullPointerException e) {
-			// do nothing
+			return null;
 		}
 
 		// not found
@@ -134,16 +134,12 @@ public static synchronized String ip(NetworkInterface nic) {
 			return ip;
 		}
 
-		try {
-			if (nic != null) {
-				Enumeration<InetAddress> ips = nic.getInetAddresses();
-				if (ips.hasMoreElements()) {
-					ip = ips.nextElement().getHostAddress();
-					return ip;
-				}
+		if (nic != null) {
+			Enumeration<InetAddress> ips = nic.getInetAddresses();
+			if (ips.hasMoreElements()) {
+				ip = ips.nextElement().getHostAddress();
+				return ip;
 			}
-		} catch (NullPointerException e) {
-			// do nothing
 		}
 
 		// not found
@@ -210,8 +206,8 @@ public static synchronized NetworkInterface nic() {
 				}
 			}
 
-		} catch (UnknownHostException | SocketException | NullPointerException e) {
-			// do nothing
+		} catch (UnknownHostException | SocketException e) {
+			return null;
 		}
 
 		// NIC not found
@@ -232,8 +228,8 @@ private static synchronized boolean acceptable(NetworkInterface nic) {
 					return true;
 				}
 			}
-		} catch (SocketException | NullPointerException e) {
-			// do nothing
+		} catch (SocketException e) {
+			return false;
 		}
 
 		return false;

src/main/java/com/github/f4b6a3/uuid/util/internal/RandomUtil.java

@@ -121,6 +121,7 @@ public static SecureRandom newSecureRandom() {
 
 	private static class SecureRandomPool {
 
+		private static final Random random = new Random();
 		private static final int POOL_SIZE = processors();
 		private static final Random[] POOL = new Random[POOL_SIZE];
 		private static final ReentrantLock lock = new ReentrantLock();
@@ -140,7 +141,7 @@ public static byte[] nextBytes(final int length) {
 			// every now and then
 			if (bytes.length > 0 && bytes[0x00] == 0) {
 				// delete a random item from the pool
-				delete((new Random()).nextInt(POOL_SIZE));
+				delete(random.nextInt(POOL_SIZE));
 			}
 
 			return bytes;