Fix onDataTreeChanged() references

[mdsal.git] / dom / mdsal-dom-api / src / main / java / org / opendaylight / mdsal / dom / api / DOMDataTreeChangeListener.java

diff --git a/dom/mdsal-dom-api/src/main/java/org/opendaylight/mdsal/dom/api/DOMDataTreeChangeListener.java b/dom/mdsal-dom-api/src/main/java/org/opendaylight/mdsal/dom/api/DOMDataTreeChangeListener.java
index efe66b4b4a337ce75d3b1c6395a2666f6b311ed2..0c0aeb23e6a07277d5bd67458978396142d7e526 100644 (file)
--- a/dom/mdsal-dom-api/src/main/java/org/opendaylight/mdsal/dom/api/DOMDataTreeChangeListener.java
+++ b/dom/mdsal-dom-api/src/main/java/org/opendaylight/mdsal/dom/api/DOMDataTreeChangeListener.java
@@ -9,35 +9,47 @@ package org.opendaylight.mdsal.dom.api;
 
 import java.util.Collection;
 import java.util.EventListener;
-import javax.annotation.Nonnull;
+import org.eclipse.jdt.annotation.NonNull;
 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
 
 /**
- * Interface implemented by classes interested in receiving notifications about
- * data tree changes. It provides a cursor-based view of the change.
+ * Interface implemented by classes interested in receiving notifications about data tree changes. It provides
+ * a cursor-based view of the change.
  */
 public interface DOMDataTreeChangeListener extends EventListener {
     /**
-     * Invoked when there was data change for the supplied path, which was used
-     * to register this listener.
+     * Invoked when there was data change for the supplied path, which was used to register this listener.
      *
      * <p>
-     * This method may be also invoked during registration of the listener if
-     * there is any pre-existing data in the conceptual data tree for supplied
-     * path. This initial event will contain all pre-existing data as created.
+     * This method may be also invoked during registration of the listener if there is any pre-existing data
+     * in the conceptual data tree for supplied path. This initial event will contain all pre-existing data as created.
      *
      * <p>
-     * A data change event may be triggered spuriously, e.g. such that data before
-     * and after compare as equal. Implementations of this interface are expected
-     * to recover from such events. Event producers are expected to exert reasonable
-     * effort to suppress such events.
-     * In other words, it is completely acceptable to observe
-     * a {@link org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidateNode},
-     * which reports a {@link org.opendaylight.yangtools.yang.data.api.schema.tree.ModificationType}
-     * other than UNMODIFIED, while the before- and after- data items compare as
-     * equal.
+     * Note: If there is no pre-existing data, the method {@link #onInitialData} will be invoked.
+     *
+     * <p>
+     * A data change event may be triggered spuriously, e.g. such that data before and after compare as equal.
+     * Implementations of this interface are expected to recover from such events. Event producers are expected to exert
+     * reasonable effort to suppress such events. In other words, it is completely acceptable to observe
+     * a {@link org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidateNode}, which reports
+     * a {@link org.opendaylight.yangtools.yang.data.api.schema.tree.ModificationType} other than UNMODIFIED, while
+     * the before- and after- data items compare as equal.
      *
      * @param changes Collection of change events, may not be null or empty.
+     * @throws NullPointerException if {@code changes} is null
+     */
+    void onDataTreeChanged(@NonNull Collection<DataTreeCandidate> changes);
+
+    /**
+     * Invoked only once during registration of the listener if there was no data in the conceptual data tree
+     * for the supplied path, which was used to register this listener, and after this
+     * {@link #onDataTreeChanged(Collection)} would always be invoked for data changes.
+     *
+     * <p>
+     * Default implementation does nothing and is appropriate for users who do not care about ascertaining
+     * initial stat.
      */
-    void onDataTreeChanged(@Nonnull Collection<DataTreeCandidate> changes);
+    default void onInitialData() {
+        //no-op
+    }
 }