Allow result and exception handler to be changed

2 files changed, 35 insertions, 8 deletions

diff --git a/src/io/StreamImpl.java b/src/io/StreamImpl.java
index c378ea3..d72f926 100644
--- a/src/io/StreamImpl.java
+++ b/src/io/StreamImpl.java
@@ -35,13 +35,17 @@ public class StreamImpl implements Stream {
 
     private final Set<String> keywords = new HashSet<>();
     /**
+     * Used for thread-safe modifications.
+     */
+    private final Object listenerSync = new Object();
+    /**
      * The target that is interested in received tweets.
      */
-    private final ResultListener resultListener;
+    private ResultListener resultListener;
     /**
      * The target that is interesting in receiving changes.
      */
-    private final ExceptionListener exceptionListener;
+    private ExceptionListener exceptionListener;
     /**
      * Used for signing messages.
      */
@@ -53,13 +57,25 @@ public class StreamImpl implements Stream {
      */
     private WorkerContainer workerContainer;
 
-    public StreamImpl(ResultListener resultListener, ExceptionListener el,
-            OAuthRequester oauth) {
-        this.resultListener = resultListener;
-        this.exceptionListener = el;
+    public StreamImpl(OAuthRequester oauth) {
         this.oauth = oauth;
     }
 
+    /**
+     * Sets the listener for new tweets.
+     *
+     * @param resultListener
+     */
+    public void setResultListener(ResultListener resultListener) {
+        this.resultListener = resultListener;
+    }
+
+    public void setExceptionListener(ExceptionListener exceptionListener) {
+        synchronized (listenerSync) {
+            this.exceptionListener = exceptionListener;
+        }
+    }
+
     @Override
     public void watchKeyword(String keyword) {
         keywords.add(keyword);
@@ -229,7 +245,13 @@ public class StreamImpl implements Stream {
                     }
                 }
                 connection.disconnect();
-                exceptionListener.exceptionGenerated(ex);
+                // synchronize just in case the exception listener gets modified
+                // while hell breaks lose.
+                synchronized (listenerSync) {
+                    if (exceptionListener != null) {
+                        exceptionListener.exceptionGenerated(ex);
+                    }
+                }
             }
         }
 
diff --git a/src/main/TweetShell.java b/src/main/TweetShell.java
index 533939b..b318544 100644
--- a/src/main/TweetShell.java
+++ b/src/main/TweetShell.java
@@ -36,7 +36,12 @@ public class TweetShell implements TwitterApi.PinSupplier {
         if (stream_cached == null) {
             OAuthRequester requester = (OAuthRequester) getApi().getRequester();
             StreamHandler handler = new StreamHandler();
-            stream_cached = new StreamImpl(handler, handler, requester);
+            stream_cached = new StreamImpl(requester);
+            StreamImpl streamObserver = (StreamImpl) stream_cached;
+            streamObserver.setExceptionListener(handler);
+            // TODO: wire up DataWriter and add a command ("target"?) to set a
+            // point to save results
+            streamObserver.setResultListener(handler);
         }
         return stream_cached;
     }