Changes

calculatorpp-core/src/main/java/org/solovyev/android/calculator/CalculatorImpl.java

@@ -38,6 +38,25 @@ import java.util.concurrent.atomic.AtomicLong;
  */
 public class CalculatorImpl implements Calculator, CalculatorEventListener {
 
+    /*
+    **********************************************************************
+    *
+    *                           CONSTANTS
+    *
+    **********************************************************************
+    */
+
+    // one minute
+    private static final long PREFERENCE_CHECK_INTERVAL = 1000L * 60L;
+
+    /*
+    **********************************************************************
+    *
+    *                           FIELDS
+    *
+    **********************************************************************
+    */
+
     @NotNull
     private final CalculatorEventContainer calculatorEventContainer = new ListCalculatorEventContainer();
 
@@ -56,10 +75,29 @@ public class CalculatorImpl implements Calculator, CalculatorEventListener {
 
     private volatile boolean calculateOnFly = true;
 
+    private volatile long lastPreferenceCheck = 0L;
+
+
+    /*
+    **********************************************************************
+    *
+    *                           CONSTRUCTORS
+    *
+    **********************************************************************
+    */
+
     public CalculatorImpl() {
         this.addCalculatorEventListener(this);
     }
 
+    /*
+    **********************************************************************
+    *
+    *                           METHODS
+    *
+    **********************************************************************
+    */
+
     @NotNull
     private CalculatorEventData nextEventData() {
         long eventId = counter.incrementAndGet();
@@ -163,7 +201,7 @@ public class CalculatorImpl implements Calculator, CalculatorEventListener {
                           @NotNull String expression,
                           @Nullable MessageRegistry mr) {
 
-        CalculatorLocatorImpl.getInstance().getPreferenceService().checkPreferredPreferences(false);
+        checkPreferredPreferences();
 
         PreparedExpression preparedExpression = null;
 
@@ -190,6 +228,7 @@ public class CalculatorImpl implements Calculator, CalculatorEventListener {
                     // NOTE: toString() method must be called here as ArithmeticOperationException may occur in it (just to avoid later check!)
                     result.toString();
 
+                    if (messageRegistry.hasMessage()) {
                         final CalculatorLogger logger = CalculatorLocatorImpl.getInstance().getLogger();
                         try {
                             final List<Message> messages = new ArrayList<Message>();
@@ -200,9 +239,10 @@ public class CalculatorImpl implements Calculator, CalculatorEventListener {
                                 fireCalculatorEvent(newCalculationEventData(operation, expression, sequenceId), CalculatorEventType.calculation_messages, messages);
                             }
                         } catch (Throwable e) {
-						// todo serso: not good be we need proper synchronization
+                            // todo serso: not good but we need proper synchronization
                             logger.error("Calculator", e.getMessage(), e);
                         }
+                    }
 
                     final CalculatorOutput data = CalculatorOutputImpl.newOutput(operation.getFromProcessor().process(result), operation, result);
                     fireCalculatorEvent(newCalculationEventData(operation, expression, sequenceId), CalculatorEventType.calculation_result, data);
@@ -228,6 +268,15 @@ public class CalculatorImpl implements Calculator, CalculatorEventListener {
         }
     }
 
+    private void checkPreferredPreferences() {
+        final long currentTime = System.currentTimeMillis();
+
+        if ( currentTime - lastPreferenceCheck > PREFERENCE_CHECK_INTERVAL ) {
+            lastPreferenceCheck = currentTime;
+            CalculatorLocatorImpl.getInstance().getPreferenceService().checkPreferredPreferences(false);
+        }
+    }
+
     @NotNull
 	@Override
 	public PreparedExpression prepareExpression(@NotNull String expression) throws CalculatorParseException {

calculatorpp/res/layout/calculator_messages_dialog_message.xml

@@ -9,7 +9,9 @@
     <TextView a:id="@+id/calculation_messages_text_view"
         a:layout_width="0dp"
         a:layout_height="wrap_content"
-        a:layout_weight="5"/>
+        a:layout_weight="5"
+        a:layout_gravity="fill"
+        a:text="@+id/calculation_messages_text_view"/>
 
     <Button
         a:id="@+id/fix_button"

calculatorpp/src/main/java/org/solovyev/android/calculator/AndroidCalculatorPreferenceService.java

@@ -20,7 +20,7 @@ import java.util.List;
  */
 public class AndroidCalculatorPreferenceService implements CalculatorPreferenceService {
 
-    // ont hour
+    // one hour
     private static final Long PREFERRED_PREFS_INTERVAL_TIME = 1000L * 60L * 60L;
 
     @NotNull