Revert "Calculator display changes"

This reverts commit b3cc081f47.

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

@@ -1,7 +1,5 @@
 package org.solovyev.android.calculator;
 
-import jscl.NumeralBase;
-import jscl.math.Generic;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.solovyev.android.calculator.jscl.JsclOperation;
@@ -24,7 +22,4 @@ public interface Calculator extends CalculatorEventContainer {
     CalculatorEventDataId evaluate(@NotNull JsclOperation operation,
                                    @NotNull String expression,
                                    @Nullable MessageRegistry mr);
-
-    @NotNull
-    CalculatorEventDataId convert(@NotNull Generic generic, @NotNull NumeralBase to);
 }

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

@@ -47,8 +47,8 @@ public class CalculatorEvaluationEventDataImpl implements CalculatorEvaluationEv
 
     @Override
     @Nullable
-    public Long getSequenceId() {
+    public Long getCalculationId() {
-        return calculatorEventData.getSequenceId();
+        return calculatorEventData.getCalculationId();
     }
 
     @Override

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

@@ -13,9 +13,8 @@ public interface CalculatorEventDataId {
     // the higher id => the later event
     long getEventId();
 
-    // the higher id => the later event
     @Nullable
-    Long getSequenceId();
+    Long getCalculationId();
 
     boolean isAfter(@NotNull CalculatorEventDataId calculatorEventDataId);
 }

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

@@ -13,16 +13,18 @@ class CalculatorEventDataIdImpl implements CalculatorEventDataId {
     private final long eventId;
 
     @Nullable
-    private final Long sequenceId;
+    private final Long calculationId;
 
-    private CalculatorEventDataIdImpl(long id, @Nullable Long sequenceId) {
+    private CalculatorEventDataIdImpl(long id,
+                                      @Nullable Long calculationId) {
         this.eventId = id;
-        this.sequenceId = sequenceId;
+        this.calculationId = calculationId;
     }
 
     @NotNull
-    static CalculatorEventDataId newInstance(long id, @Nullable Long sequenceId) {
+    static CalculatorEventDataId newInstance(long id,
-        return new CalculatorEventDataIdImpl(id, sequenceId);
+                                                    @Nullable Long calculationId) {
+        return new CalculatorEventDataIdImpl(id, calculationId);
     }
 
     @Override
@@ -32,8 +34,8 @@ class CalculatorEventDataIdImpl implements CalculatorEventDataId {
 
     @Nullable
     @Override
-    public Long getSequenceId() {
+    public Long getCalculationId() {
-        return this.sequenceId;
+        return this.calculationId;
     }
 
     @Override
@@ -49,7 +51,7 @@ class CalculatorEventDataIdImpl implements CalculatorEventDataId {
         CalculatorEventDataIdImpl that = (CalculatorEventDataIdImpl) o;
 
         if (eventId != that.eventId) return false;
-        if (sequenceId != null ? !sequenceId.equals(that.sequenceId) : that.sequenceId != null)
+        if (calculationId != null ? !calculationId.equals(that.calculationId) : that.calculationId != null)
             return false;
 
         return true;
@@ -58,7 +60,7 @@ class CalculatorEventDataIdImpl implements CalculatorEventDataId {
     @Override
     public int hashCode() {
         int result = (int) (eventId ^ (eventId >>> 32));
-        result = 31 * result + (sequenceId != null ? sequenceId.hashCode() : 0);
+        result = 31 * result + (calculationId != null ? calculationId.hashCode() : 0);
         return result;
     }
 }

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

@@ -29,8 +29,8 @@ class CalculatorEventDataImpl implements CalculatorEventData {
 
     @Override
     @Nullable
-    public Long getSequenceId() {
+    public Long getCalculationId() {
-        return calculatorEventDataId.getSequenceId();
+        return calculatorEventDataId.getCalculationId();
     }
 
     @Override

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

@@ -28,19 +28,7 @@ public enum CalculatorEventType {
     calculation_finished,
 
     // @NotNull org.solovyev.android.calculator.CalculatorFailure
-    calculation_failed,
+    calculation_failed;
-
-    /*
-    **********************************************************************
-    *
-    *                           CONVERSION
-    *
-    **********************************************************************
-    */
-    conversion_started,
-
-    // @NotNull String conversion result
-    conversion_finished;
 
     public boolean isOfType(@NotNull CalculatorEventType... types) {
         for (CalculatorEventType type : types) {

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

@@ -1,7 +1,6 @@
 package org.solovyev.android.calculator;
 
 import jscl.AbstractJsclArithmeticException;
-import jscl.NumeralBase;
 import jscl.NumeralBaseException;
 import jscl.math.Generic;
 import jscl.text.ParseInterruptedException;
@@ -11,10 +10,6 @@ import org.solovyev.android.calculator.jscl.JsclOperation;
 import org.solovyev.android.calculator.text.TextProcessor;
 import org.solovyev.common.msg.MessageRegistry;
 import org.solovyev.common.msg.MessageType;
-import org.solovyev.common.text.StringUtils;
-import org.solovyev.math.units.UnitConverter;
-import org.solovyev.math.units.UnitImpl;
-import org.solovyev.math.units.UnitType;
 
 import java.util.List;
 import java.util.concurrent.Executor;
@@ -48,32 +43,6 @@ public class CalculatorImpl implements Calculator {
     public CalculatorImpl() {
     }
 
-    @NotNull
-    public static String doConversion(@NotNull UnitConverter<String> converter,
-                                      @Nullable String from,
-                                      @NotNull UnitType<String> fromUnitType,
-                                      @NotNull UnitType<String> toUnitType) throws ConversionException{
-        final String result;
-
-        if (StringUtils.isEmpty(from)) {
-            result = "";
-        } else {
-
-            String to = null;
-            try {
-                if (converter.isSupported(fromUnitType, toUnitType)) {
-                    to = converter.convert(UnitImpl.newInstance(from, fromUnitType), toUnitType).getValue();
-                }
-            } catch (RuntimeException e) {
-                throw new ConversionException(e);
-            }
-
-            result = to;
-        }
-
-        return result;
-    }
-
     @NotNull
     private CalculatorEventDataId nextCalculatorEventDataId() {
         long eventId = counter.incrementAndGet();
@@ -81,9 +50,9 @@ public class CalculatorImpl implements Calculator {
     }
 
     @NotNull
-    private CalculatorEventDataId nextEventDataId(@NotNull Long sequenceId) {
+    private CalculatorEventDataId nextEventDataId(@NotNull Long calculationId) {
         long eventId = counter.incrementAndGet();
-        return CalculatorEventDataIdImpl.newInstance(eventId, sequenceId);
+        return CalculatorEventDataIdImpl.newInstance(eventId, calculationId);
     }
 
     /*
@@ -117,56 +86,14 @@ public class CalculatorImpl implements Calculator {
         threadPoolExecutor.execute(new Runnable() {
             @Override
             public void run() {
-                CalculatorImpl.this.evaluate(eventDataId.getSequenceId(), operation, expression, mr);
+                CalculatorImpl.this.evaluate(eventDataId.getCalculationId(), operation, expression, mr);
             }
         });
 
         return eventDataId;
     }
 
-    @NotNull
+    private void evaluate(@NotNull Long calculationId,
-    @Override
-    public CalculatorEventDataId convert(@NotNull final Generic generic,
-                                         @NotNull final NumeralBase to) {
-        final CalculatorEventDataId eventDataId = nextCalculatorEventDataId();
-
-        threadPoolExecutor.execute(new Runnable() {
-            @Override
-            public void run() {
-                final Long sequenceId = eventDataId.getSequenceId();
-                assert sequenceId != null;
-
-                fireCalculatorEvent(newConversionEventData(sequenceId), CalculatorEventType.conversion_started, null);
-
-                final NumeralBase from = CalculatorLocatorImpl.getInstance().getCalculatorEngine().getEngine().getNumeralBase();
-
-                if (from != to) {
-                    String fromString = generic.toString();
-                    if (!StringUtils.isEmpty(fromString)) {
-                        try {
-                            fromString = ToJsclTextProcessor.getInstance().process(fromString).getExpression();
-                        } catch (CalculatorParseException e) {
-                            // ok, problems while processing occurred
-                        }
-                    }
-
-                    // todo serso: continue
-                    //doConversion(AndroidNumeralBase.getConverter(), fromString, AndroidNumeralBase.valueOf(fromString), AndroidNumeralBase.valueOf(to));
-                } else {
-                    fireCalculatorEvent(newConversionEventData(sequenceId), CalculatorEventType.conversion_finished, generic.toString());
-                }
-            }
-        });
-
-        return eventDataId;
-    }
-
-    @NotNull
-    private CalculatorEventData newConversionEventData(@NotNull Long sequenceId) {
-        return CalculatorEventDataImpl.newInstance(nextEventDataId(sequenceId));
-    }
-
-    private void evaluate(@NotNull Long sequenceId,
                           @NotNull JsclOperation operation,
                           @NotNull String expression,
                           @Nullable MessageRegistry mr) {
@@ -174,7 +101,7 @@ public class CalculatorImpl implements Calculator {
 
             PreparedExpression preparedExpression = null;
 
-            fireCalculatorEvent(newCalculationEventData(operation, expression, sequenceId), CalculatorEventType.calculation_started, new CalculatorInputImpl(expression, operation));
+            fireCalculatorEvent(newCalculationEventData(operation, expression, calculationId), CalculatorEventType.calculation_started, new CalculatorInputImpl(expression, operation));
 
             try {
                 preparedExpression = preprocessor.process(expression);
@@ -189,27 +116,27 @@ public class CalculatorImpl implements Calculator {
                     result.toString();
 
                     final CalculatorOutputImpl data = new CalculatorOutputImpl(operation.getFromProcessor().process(result), operation, result);
-                    fireCalculatorEvent(newCalculationEventData(operation, expression, sequenceId), CalculatorEventType.calculation_result, data);
+                    fireCalculatorEvent(newCalculationEventData(operation, expression, calculationId), CalculatorEventType.calculation_result, data);
 
                 } catch (AbstractJsclArithmeticException e) {
-                    handleException(sequenceId, operation, expression, mr, new CalculatorEvalException(e, e, jsclExpression));
+                    handleException(calculationId, operation, expression, mr, new CalculatorEvalException(e, e, jsclExpression));
                 }
 
             } catch (ArithmeticException e) {
-                handleException(sequenceId, operation, expression, mr, preparedExpression, new CalculatorParseException(expression, new CalculatorMessage(CalculatorMessages.msg_001, MessageType.error, e.getMessage())));
+                handleException(calculationId, operation, expression, mr, preparedExpression, new CalculatorParseException(expression, new CalculatorMessage(CalculatorMessages.msg_001, MessageType.error, e.getMessage())));
             } catch (StackOverflowError e) {
-                handleException(sequenceId, operation, expression, mr, preparedExpression, new CalculatorParseException(expression, new CalculatorMessage(CalculatorMessages.msg_002, MessageType.error)));
+                handleException(calculationId, operation, expression, mr, preparedExpression, new CalculatorParseException(expression, new CalculatorMessage(CalculatorMessages.msg_002, MessageType.error)));
             } catch (jscl.text.ParseException e) {
-                handleException(sequenceId, operation, expression, mr, preparedExpression, new CalculatorParseException(e));
+                handleException(calculationId, operation, expression, mr, preparedExpression, new CalculatorParseException(e));
             } catch (ParseInterruptedException e) {
 
                 // do nothing - we ourselves interrupt the calculations
-                fireCalculatorEvent(newCalculationEventData(operation, expression, sequenceId), CalculatorEventType.calculation_cancelled, null);
+                fireCalculatorEvent(newCalculationEventData(operation, expression, calculationId), CalculatorEventType.calculation_cancelled, null);
 
             } catch (CalculatorParseException e) {
-                handleException(sequenceId, operation, expression, mr, preparedExpression, e);
+                handleException(calculationId, operation, expression, mr, preparedExpression, e);
             } finally {
-                fireCalculatorEvent(newCalculationEventData(operation, expression, sequenceId), CalculatorEventType.calculation_finished, null);
+                fireCalculatorEvent(newCalculationEventData(operation, expression, calculationId), CalculatorEventType.calculation_finished, null);
             }
         }
     }
@@ -279,13 +206,4 @@ public class CalculatorImpl implements Calculator {
     public void fireCalculatorEvents(@NotNull List<CalculatorEvent> calculatorEvents) {
         calculatorEventContainer.fireCalculatorEvents(calculatorEvents);
     }
-
-    public static final class ConversionException extends Exception {
-        private ConversionException() {
-        }
-
-        private ConversionException(Throwable throwable) {
-            super(throwable);
-        }
-    }
 }

calculatorpp/project.properties

@@ -9,11 +9,12 @@
 
 # Project target.
 target=android-15
-android.library.reference.1=gen-external-apklibs/org.solovyev.android_android-common-core_1.0.0
+android.library.reference.1=../calculatorpp-service
-android.library.reference.2=gen-external-apklibs/org.solovyev.android_android-common-ads_1.0.0
+android.library.reference.2=gen-external-apklibs/org.solovyev.android_android-common-core_1.0.0
-android.library.reference.3=gen-external-apklibs/org.solovyev.android_android-common-view_1.0.0
+android.library.reference.3=gen-external-apklibs/org.solovyev.android_android-common-ads_1.0.0
-android.library.reference.4=gen-external-apklibs/org.solovyev.android_android-common-preferences_1.0.0
+android.library.reference.4=gen-external-apklibs/org.solovyev.android_android-common-view_1.0.0
-android.library.reference.5=gen-external-apklibs/org.solovyev.android_android-common-other_1.0.0
+android.library.reference.5=gen-external-apklibs/org.solovyev.android_android-common-preferences_1.0.0
-android.library.reference.6=gen-external-apklibs/org.solovyev.android_android-common-menu_1.0.0
+android.library.reference.6=gen-external-apklibs/org.solovyev.android_android-common-other_1.0.0
+android.library.reference.7=gen-external-apklibs/org.solovyev.android_android-common-menu_1.0.0
 
 

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

@@ -10,6 +10,7 @@ import android.graphics.Color;
 import android.text.Html;
 import android.util.AttributeSet;
 import android.util.Log;
+import jscl.NumeralBase;
 import jscl.math.Generic;
 import jscl.math.function.Constant;
 import jscl.math.function.IConstant;
@@ -19,9 +20,12 @@ import org.solovyev.android.calculator.model.CalculatorEngine;
 import org.solovyev.android.calculator.text.TextProcessor;
 import org.solovyev.android.calculator.view.NumeralBaseConverterDialog;
 import org.solovyev.android.calculator.view.TextHighlighter;
+import org.solovyev.android.calculator.view.UnitConverterViewBuilder;
+import org.solovyev.android.menu.AMenuItem;
 import org.solovyev.android.menu.LabeledMenuItem;
 import org.solovyev.android.view.AutoResizeTextView;
 import org.solovyev.common.collections.CollectionsUtils;
+import org.solovyev.common.text.StringUtils;
 
 import java.util.HashSet;
 import java.util.Set;
@@ -33,18 +37,95 @@ import java.util.Set;
  */
 public class AndroidCalculatorDisplayView extends AutoResizeTextView implements CalculatorDisplayView {
 
-    public static enum MenuItem implements LabeledMenuItem<CalculatorDisplayViewState> {
+    private static enum ConversionMenuItem implements AMenuItem<CalculatorDisplayView> {
+        convert_to_bin(NumeralBase.bin),
+        convert_to_dec(NumeralBase.dec),
+        convert_to_hex(NumeralBase.hex);
+
+        @NotNull
+        private final NumeralBase toNumeralBase;
+
+        private ConversionMenuItem(@NotNull NumeralBase toNumeralBase) {
+            this.toNumeralBase = toNumeralBase;
+        }
+
+        protected boolean isItemVisibleFor(@NotNull Generic generic, @NotNull JsclOperation operation) {
+            boolean result = false;
+
+            if (operation == JsclOperation.numeric) {
+                if (generic.getConstants().isEmpty()) {
+                    try {
+                        convert(generic);
+
+                        // conversion possible => return true
+                        result = true;
+
+                    } catch (UnitConverterViewBuilder.ConversionException e) {
+                        // conversion is not possible => return false
+                    }
+                }
+            }
+
+            return result;
+        }
+
+        @Override
+        public void onClick(@NotNull CalculatorDisplayView data, @NotNull Context context) {
+            final NumeralBase fromNumeralBase = CalculatorEngine.instance.getEngine().getNumeralBase();
+
+            final Generic lastResult = CalculatorLocatorImpl.getInstance().getCalculatorDisplay().getViewState().getResult();
+
+            if (lastResult != null) {
+                String to;
+                try {
+                    to = convert(lastResult);
+
+                    // add prefix
+                    if (fromNumeralBase != toNumeralBase) {
+                        to = toNumeralBase.getJsclPrefix() + to;
+                    }
+                } catch (UnitConverterViewBuilder.ConversionException e) {
+                    to = context.getString(R.string.c_error);
+                }
+
+                data.setText(to);
+                //data.redraw();
+            }
+        }
+
+        @NotNull
+        private String convert(@NotNull Generic generic) throws UnitConverterViewBuilder.ConversionException {
+            final NumeralBase fromNumeralBase = CalculatorEngine.instance.getEngine().getNumeralBase();
+
+            if (fromNumeralBase != toNumeralBase) {
+                String from = generic.toString();
+                if (!StringUtils.isEmpty(from)) {
+                    try {
+                        from = ToJsclTextProcessor.getInstance().process(from).getExpression();
+                    } catch (CalculatorParseException e) {
+                        // ok, problems while processing occurred
+                    }
+                }
+
+                return UnitConverterViewBuilder.doConversion(AndroidNumeralBase.getConverter(), from, AndroidNumeralBase.valueOf(fromNumeralBase), AndroidNumeralBase.valueOf(toNumeralBase));
+            } else {
+                return generic.toString();
+            }
+        }
+    }
+
+    public static enum MenuItem implements LabeledMenuItem<CalculatorDisplayView> {
 
         copy(R.string.c_copy) {
             @Override
-            public void onClick(@NotNull CalculatorDisplayViewState data, @NotNull Context context) {
+            public void onClick(@NotNull CalculatorDisplayView data, @NotNull Context context) {
                 CalculatorModel.copyResult(context, data);
             }
         },
 
         convert_to_bin(R.string.convert_to_bin) {
             @Override
-            public void onClick(@NotNull CalculatorDisplayViewState data, @NotNull Context context) {
+            public void onClick(@NotNull CalculatorDisplayView data, @NotNull Context context) {
                 ConversionMenuItem.convert_to_bin.onClick(data, context);
             }
 
@@ -56,7 +137,7 @@ public class AndroidCalculatorDisplayView extends AutoResizeTextView implements
 
         convert_to_dec(R.string.convert_to_dec) {
             @Override
-            public void onClick(@NotNull CalculatorDisplayViewState data, @NotNull Context context) {
+            public void onClick(@NotNull CalculatorDisplayView data, @NotNull Context context) {
                 ConversionMenuItem.convert_to_dec.onClick(data, context);
             }
 
@@ -68,7 +149,7 @@ public class AndroidCalculatorDisplayView extends AutoResizeTextView implements
 
         convert_to_hex(R.string.convert_to_hex) {
             @Override
-            public void onClick(@NotNull CalculatorDisplayViewState data, @NotNull Context context) {
+            public void onClick(@NotNull CalculatorDisplayView data, @NotNull Context context) {
                 ConversionMenuItem.convert_to_hex.onClick(data, context);
             }
 
@@ -80,8 +161,8 @@ public class AndroidCalculatorDisplayView extends AutoResizeTextView implements
 
         convert(R.string.c_convert) {
             @Override
-            public void onClick(@NotNull CalculatorDisplayViewState data, @NotNull Context context) {
+            public void onClick(@NotNull CalculatorDisplayView data, @NotNull Context context) {
-                final Generic result = data.getResult();
+                final Generic result = data.getState().getResult();
                 if (result != null) {
                     new NumeralBaseConverterDialog(result.toString()).show(context);
                 }
@@ -95,8 +176,8 @@ public class AndroidCalculatorDisplayView extends AutoResizeTextView implements
 
         plot(R.string.c_plot) {
             @Override
-            public void onClick(@NotNull CalculatorDisplayViewState data, @NotNull Context context) {
+            public void onClick(@NotNull CalculatorDisplayView data, @NotNull Context context) {
-                final Generic generic = data.getResult();
+                final Generic generic = data.getState().getResult();
                 assert generic != null;
 
                 final Constant constant = CollectionsUtils.getFirstCollectionElement(getNotSystemConstants(generic));

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

@@ -97,9 +97,10 @@ public enum CalculatorModel implements CursorControl, HistoryControl<CalculatorH
 		copyResult(context, display);
 	}
 
-	public static void copyResult(@NotNull Context context, @NotNull final CalculatorDisplayViewState viewState) {
+	public static void copyResult(@NotNull Context context, @NotNull final CalculatorDisplayView display) {
-		if (viewState.isValid()) {
+        final CalculatorDisplayViewState displayViewState = display.getState();
-			final CharSequence text = viewState.getText();
+		if (displayViewState.isValid()) {
+			final CharSequence text = display.getText();
 			if (!StringUtils.isEmpty(text)) {
 				final ClipboardManager clipboard = (ClipboardManager) context.getSystemService(Activity.CLIPBOARD_SERVICE);
 				clipboard.setText(text.toString());

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

@@ -1,63 +0,0 @@
-package org.solovyev.android.calculator;
-
-import android.content.Context;
-import jscl.NumeralBase;
-import jscl.math.Generic;
-import org.jetbrains.annotations.NotNull;
-import org.solovyev.android.calculator.jscl.JsclOperation;
-import org.solovyev.android.calculator.model.CalculatorEngine;
-import org.solovyev.android.menu.AMenuItem;
-
-/**
- * User: serso
- * Date: 9/21/12
- * Time: 12:11 AM
- */
-enum ConversionMenuItem implements AMenuItem<CalculatorDisplayViewState> {
-
-    convert_to_bin(NumeralBase.bin),
-    convert_to_dec(NumeralBase.dec),
-    convert_to_hex(NumeralBase.hex);
-
-    @NotNull
-    private final NumeralBase toNumeralBase;
-
-    ConversionMenuItem(@NotNull NumeralBase toNumeralBase) {
-        this.toNumeralBase = toNumeralBase;
-    }
-
-    protected boolean isItemVisibleFor(@NotNull Generic generic, @NotNull JsclOperation operation) {
-        boolean result = false;
-
-        if (operation == JsclOperation.numeric) {
-            if (generic.getConstants().isEmpty()) {
-                try {
-                    convert(generic);
-
-                    // conversion possible => return true
-                    result = true;
-
-                } catch (CalculatorImpl.ConversionException e) {
-                    // conversion is not possible => return false
-                }
-            }
-        }
-
-        return result;
-    }
-
-    @Override
-    public void onClick(@NotNull CalculatorDisplayViewState data, @NotNull Context context) {
-        final NumeralBase fromNumeralBase = CalculatorEngine.instance.getEngine().getNumeralBase();
-
-        final Generic lastResult = data.getResult();
-
-        if (lastResult != null) {
-            convert(lastResult);
-        }
-    }
-
-    private void convert(@NotNull Generic generic) {
-        CalculatorLocatorImpl.getInstance().getCalculator().convert(generic, this.toNumeralBase);
-    }
-}

calculatorpp/src/main/java/org/solovyev/android/calculator/view/UnitConverterViewBuilder.java

@@ -10,7 +10,6 @@ import android.view.ViewGroup;
 import android.widget.*;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
-import org.solovyev.android.calculator.CalculatorImpl;
 import org.solovyev.math.units.Unit;
 import org.solovyev.math.units.UnitConverter;
 import org.solovyev.math.units.UnitImpl;
@@ -18,6 +17,7 @@ import org.solovyev.math.units.UnitType;
 import org.solovyev.android.calculator.R;
 import org.solovyev.android.view.ViewBuilder;
 import org.solovyev.android.view.ViewFromLayoutBuilder;
+import org.solovyev.common.text.StringUtils;
 
 import java.util.Collections;
 import java.util.List;
@@ -173,12 +173,47 @@ public class UnitConverterViewBuilder implements ViewBuilder<View> {
 
         final String from = fromEditText.getText().toString();
         try {
-            toEditText.setText(CalculatorImpl.doConversion(converter, from, getFromUnitType(main), getToUnitType(main)));
+            toEditText.setText(doConversion(converter, from, getFromUnitType(main), getToUnitType(main)));
-        } catch (CalculatorImpl.ConversionException e) {
+        } catch (ConversionException e) {
             toEditText.setText(context.getString(R.string.c_error));
         }
     }
 
+    public static final class ConversionException extends Exception {
+        private ConversionException() {
+        }
+
+        private ConversionException(Throwable throwable) {
+            super(throwable);
+        }
+    }
+
+    @NotNull
+    public static String doConversion(@NotNull UnitConverter<String> converter,
+                                      @Nullable String from,
+                                      @NotNull UnitType<String> fromUnitType,
+                                      @NotNull UnitType<String> toUnitType) throws ConversionException{
+        final String result;
+
+        if (StringUtils.isEmpty(from)) {
+            result = "";
+        } else {
+
+            String to = null;
+            try {
+                if (converter.isSupported(fromUnitType, toUnitType)) {
+                    to = converter.convert(UnitImpl.newInstance(from, fromUnitType), toUnitType).getValue();
+                }
+            } catch (RuntimeException e) {
+                throw new ConversionException(e);
+            }
+
+            result = to;
+        }
+
+        return result;
+    }
+
     @NotNull
     private static Unit<String> getToUnit(@NotNull View main) {
         final EditText toUnits = (EditText) main.findViewById(R.id.units_to);