3 files changed, 19 insertions, 7 deletions
diff --git a/same/src/main/java/com/orbekk/same/Variable.java b/same/src/main/java/com/orbekk/same/Variable.java
index 4d42909..7f9f4d5 100644
--- a/same/src/main/java/com/orbekk/same/Variable.java
+++ b/same/src/main/java/com/orbekk/same/Variable.java
@@ -15,5 +15,6 @@ public interface Variable<T> {
     T get();
     DelayedOperation set(T value);
     void update();
-    void setOnChangeListener(OnChangeListener<T> listener);
+    void addOnChangeListener(OnChangeListener<T> listener);
+    void removeOnChangeListener(OnChangeListener<T> listener);
 }
diff --git a/same/src/main/java/com/orbekk/same/VariableFactory.java b/same/src/main/java/com/orbekk/same/VariableFactory.java
index fa9eeeb..e04e36b 100644
--- a/same/src/main/java/com/orbekk/same/VariableFactory.java
+++ b/same/src/main/java/com/orbekk/same/VariableFactory.java
@@ -1,6 +1,7 @@
 package com.orbekk.same;
 
 import java.io.IOException;
+import java.util.ArrayList;
 
 import org.codehaus.jackson.JsonGenerationException;
 import org.codehaus.jackson.map.JsonMappingException;
@@ -25,7 +26,8 @@ public class VariableFactory {
         TypeReference<T> type;
         T value;
         long revision = 0;
-        OnChangeListener<T> listener = null;
+        ArrayList<OnChangeListener<T>> listeners =
+                new ArrayList<OnChangeListener<T>>();
 
         public VariableImpl(String identifier, TypeReference<T> type) {
             this.identifier = identifier;
@@ -66,14 +68,19 @@ public class VariableFactory {
         }
 
         @Override
-        public void setOnChangeListener(OnChangeListener<T> listener) {
-            this.listener = listener;
+        public synchronized void addOnChangeListener(OnChangeListener<T> listener) {
+            listeners.add(listener);
+        }
+        
+        @Override
+        public synchronized void removeOnChangeListener(OnChangeListener<T> listener) {
+            listeners.remove(listener);
         }
 
         @Override
-        public void stateChanged(Component component) {
+        public synchronized void stateChanged(Component component) {
             if (component.getName().equals(identifier)) {
-                if (listener != null) {
+                for (OnChangeListener<T> listener : listeners) {
                     listener.valueChanged(this);
                 }
             }
diff --git a/same/src/main/java/com/orbekk/same/VariableUpdaterTask.java b/same/src/main/java/com/orbekk/same/VariableUpdaterTask.java
index 471dbc6..f696e17 100644
--- a/same/src/main/java/com/orbekk/same/VariableUpdaterTask.java
+++ b/same/src/main/java/com/orbekk/same/VariableUpdaterTask.java
@@ -7,11 +7,12 @@ import java.util.concurrent.atomic.AtomicBoolean;
 public class VariableUpdaterTask<T> extends Thread
         implements Variable.OnChangeListener<T> {
     private Variable<T> variable;
-    private T newValue;
+    private volatile T newValue;
     private AtomicBoolean hasNewValue = new AtomicBoolean(false);
     private AtomicBoolean isReady = new AtomicBoolean(true);
     
     public VariableUpdaterTask(Variable<T> variable) {
+        super("VariableUpdater");
         this.variable = variable;
     }
     
@@ -47,7 +48,9 @@ public class VariableUpdaterTask<T> extends Thread
         }
     }
     
+    @Override
     public void run() {
+        variable.addOnChangeListener(this);
         while (true) {
             waitFor(isReady);
             waitFor(hasNewValue);
@@ -56,6 +59,7 @@ public class VariableUpdaterTask<T> extends Thread
             }
             performWork();
         }
+        variable.removeOnChangeListener(this);
     }
 
     @Override