Introduce typed UUIDs.

[lgpl/argeo-commons.git] / org.argeo.api.uuid / src / org / argeo / api / uuid / UuidHolder.java

diff --git a/org.argeo.api.uuid/src/org/argeo/api/uuid/UuidHolder.java b/org.argeo.api.uuid/src/org/argeo/api/uuid/UuidHolder.java
new file mode 100644 (file)
index 0000000..253f0ad
--- /dev/null
+++ b/org.argeo.api.uuid/src/org/argeo/api/uuid/UuidHolder.java
@@ -0,0 +1,71 @@
+package org.argeo.api.uuid;
+
+import java.io.Serializable;
+import java.util.Objects;
+import java.util.UUID;
+import java.util.function.Supplier;
+
+/**
+ * An immutable wrapper for an {@link UUID}, which can be used as a base for a
+ * derivation hierarchy, while strongly enforcing semantic equality with the
+ * underlying {@link UUID}. It is therefore immutable, and all base methods are
+ * directly and trivially based on {@link UUID} methods; they do represent the
+ * same unique "thing" (be it an entity, a point in time, etc.), consistently
+ * with the fundamental concept of uuid.
+ */
+public class UuidHolder implements Supplier<UUID>, Serializable {
+       private static final long serialVersionUID = APM.SERIAL;
+
+       /**
+        * The wrapped {@link UUID}. Protected rather than private, since it is
+        * immutable and a {@link UUID} is itself immutable.
+        */
+       protected final UUID uuid;
+
+       /**
+        * Constructs a new {@link UuidHolder} based on this uuid.
+        * 
+        * @param uuid the UUID to wrap, cannot be null.
+        * @throws NullPointerException if the provided uuid is null.
+        */
+       protected UuidHolder(UUID uuid) {
+               Objects.requireNonNull(uuid, "UUID cannot be null");
+               this.uuid = uuid;
+       }
+
+       /** The wrapped {@link UUID}. */
+       public final UUID getUuid() {
+               return uuid;
+       }
+
+       /** The wrapped {@link UUID}. */
+       @Override
+       public final UUID get() {
+               return getUuid();
+       }
+
+       /** Calls {@link UUID#hashCode()} on the wrapped {@link UUID}. */
+       @Override
+       public final int hashCode() {
+               return uuid.hashCode();
+       }
+
+       /**
+        * Equals only with non-null {@link UuidHolder} if and only if their wrapped
+        * uuid are equals by calling {@link UUID#equals(Object)}.
+        */
+       @Override
+       public final boolean equals(Object obj) {
+               if (obj == null || !(obj instanceof UuidHolder))
+                       return false;
+               UuidHolder typedUuid = (UuidHolder) obj;
+               return uuid.equals(typedUuid.uuid);
+       }
+
+       /** Calls {@link UUID#toString()} on the wrapped {@link UUID}. */
+       @Override
+       public final String toString() {
+               return uuid.toString();
+       }
+
+}