listen for new/removed power managers

JMRI · Feb 23, 2018 · 81e4945 · 81e4945
1 parent a9ba081
commit 81e4945
Showing 1 changed file with 20 additions and 3 deletions.
diff --git a/java/src/jmri/BlockManager.java b/java/src/jmri/BlockManager.java
@@ -40,13 +40,17 @@
  */
 public class BlockManager extends AbstractManager<Block> implements PropertyChangeListener, VetoableChangeListener, InstanceManagerAutoDefault {
 
+    private String powerManagerChangeName;
+
     public BlockManager() {
         super();
-        InstanceManager.sensorManagerInstance().addVetoableChangeListener(this);
+        InstanceManager.getDefault(SensorManager.class).addVetoableChangeListener(this);
         InstanceManager.getDefault(ReporterManager.class).addVetoableChangeListener(this);
         InstanceManager.getList(PowerManager.class).forEach((pm) -> {
             pm.addPropertyChangeListener(this);
         });
+        powerManagerChangeName = InstanceManager.getListPropertyName(PowerManager.class);
+        InstanceManager.addPropertyChangeListener(this);
     }
 
     @Override
@@ -317,11 +321,13 @@ public List<Block> getBlocksOccupiedByRosterEntry(@Nonnull RosterEntry re) {
 
     /**
      * Listen for changes to the power state from any power managers
-     * in use in order to track how long it's been since powet was applied
+     * in use in order to track how long it's been since power was applied
      * to the layout. This information is used in {@link Block#goingActive()}
      * when deciding whether to restore a block's last value.
      *
-     * @param e
+     * Also listen for additions/removals or PowerManagers
+     *
+     * @param e - the change event
      */
 
     @Override
@@ -337,6 +343,17 @@ public void propertyChange(PropertyChangeEvent e) {
                 // do nothing
             }
         }
+        if (powerManagerChangeName.equals(e.getPropertyName())) {
+            if (e.getNewValue() == null) {
+                // powermanager has been removed
+                PowerManager pm = (PowerManager) e.getOldValue();
+                pm.removePropertyChangeListener(this);
+            } else {
+                // a powermanager has been added
+                PowerManager pm = (PowerManager) e.getNewValue();
+                pm.addPropertyChangeListener(this);
+            }
+        }
     }