Implemented unit conversion, with a few problems

TabbedView now displays its units, but with their toString method which shows
their definition in addition to their name

27 files changed, 299 insertions, 72 deletions

diff --git a/CHANGELOG.org b/CHANGELOG.org
index 2abee52..3bc46c2 100644
--- a/CHANGELOG.org
+++ b/CHANGELOG.org
@@ -4,8 +4,11 @@
 *** Added
     - Added tests for the GUI
     - Added an object for the version numbers (SemanticVersionNumber)
+    - Added some toString methods to NameSymbol
 *** Changed
     - Rewrote the GUI code internally using an MVP model to make it easier to maintain and improve
+    - BaseDimension is now Nameable.  As a consequence, its name and symbol return Optional<String> instead of String, even though they will always succeed.
+    - The UnitDatabase's units and dimensions are now always named
     - Tweaked the look of the unit and expression conversion sections of the view
 ** v0.3.2 - [2021-12-02 Thu]
 *** Added
diff --git a/src/main/java/sevenUnits/converterGUI/SevenUnitsGUI.java b/src/main/java/sevenUnits/converterGUI/SevenUnitsGUI.java
index 9c6ae0a..55e1546 100644
--- a/src/main/java/sevenUnits/converterGUI/SevenUnitsGUI.java
+++ b/src/main/java/sevenUnits/converterGUI/SevenUnitsGUI.java
@@ -70,12 +70,12 @@ import sevenUnits.unit.BritishImperial;
 import sevenUnits.unit.LinearUnit;
 import sevenUnits.unit.LinearUnitValue;
 import sevenUnits.unit.Metric;
-import sevenUnits.unit.NameSymbol;
 import sevenUnits.unit.Unit;
 import sevenUnits.unit.UnitDatabase;
 import sevenUnits.unit.UnitPrefix;
 import sevenUnits.unit.UnitValue;
 import sevenUnits.utils.ConditionalExistenceCollections;
+import sevenUnits.utils.NameSymbol;
 import sevenUnits.utils.ObjectProduct;
 
 /**
diff --git a/src/main/java/sevenUnits/unit/BaseDimension.java b/src/main/java/sevenUnits/unit/BaseDimension.java
index d5e98ca..bcd57d9 100644
--- a/src/main/java/sevenUnits/unit/BaseDimension.java
+++ b/src/main/java/sevenUnits/unit/BaseDimension.java
@@ -18,70 +18,58 @@ package sevenUnits.unit;
 
 import java.util.Objects;
 
+import sevenUnits.utils.NameSymbol;
+import sevenUnits.utils.Nameable;
+
 /**
  * A dimension that defines a {@code BaseUnit}
  * 
  * @author Adrien Hopkins
  * @since 2019-10-16
  */
-public final class BaseDimension {
+public final class BaseDimension implements Nameable {
 	/**
 	 * Gets a {@code BaseDimension} with the provided name and symbol.
 	 * 
-	 * @param name
-	 *            name of dimension
-	 * @param symbol
-	 *            symbol used for dimension
+	 * @param name   name of dimension
+	 * @param symbol symbol used for dimension
 	 * @return dimension
 	 * @since 2019-10-16
 	 */
 	public static BaseDimension valueOf(final String name, final String symbol) {
 		return new BaseDimension(name, symbol);
 	}
-
+	
 	/**
 	 * The name of the dimension.
 	 */
 	private final String name;
 	/**
-	 * The symbol used by the dimension. Symbols should be short, generally one or two characters.
+	 * The symbol used by the dimension. Symbols should be short, generally one
+	 * or two characters.
 	 */
 	private final String symbol;
-
+	
 	/**
 	 * Creates the {@code BaseDimension}.
 	 * 
-	 * @param name
-	 *            name of unit
-	 * @param symbol
-	 *            symbol of unit
-	 * @throws NullPointerException
-	 *             if any argument is null
+	 * @param name   name of unit
+	 * @param symbol symbol of unit
+	 * @throws NullPointerException if any argument is null
 	 * @since 2019-10-16
 	 */
 	private BaseDimension(final String name, final String symbol) {
 		this.name = Objects.requireNonNull(name, "name must not be null.");
 		this.symbol = Objects.requireNonNull(symbol, "symbol must not be null.");
 	}
-
-	/**
-	 * @return name
-	 * @since 2019-10-16
-	 */
-	public final String getName() {
-		return this.name;
-	}
-
-	/**
-	 * @return symbol
-	 * @since 2019-10-16
-	 */
-	public final String getSymbol() {
-		return this.symbol;
+	
+	@Override
+	public NameSymbol getNameSymbol() {
+		return NameSymbol.of(this.name, this.symbol);
 	}
-
+	
 	@Override
 	public String toString() {
-		return String.format("%s (%s)", this.getName(), this.getSymbol());
+		return String.format("%s (%s)", this.name, this.symbol);
 	}
 }
diff --git a/src/main/java/sevenUnits/unit/BaseUnit.java b/src/main/java/sevenUnits/unit/BaseUnit.java
index ee2c277..dba7f52 100644
--- a/src/main/java/sevenUnits/unit/BaseUnit.java
+++ b/src/main/java/sevenUnits/unit/BaseUnit.java
@@ -20,6 +20,8 @@ import java.util.HashSet;
 import java.util.Objects;
 import java.util.Set;
 
+import sevenUnits.utils.NameSymbol;
+
 /**
  * A unit that other units are defined by.
  * <p>
diff --git a/src/main/java/sevenUnits/unit/BritishImperial.java b/src/main/java/sevenUnits/unit/BritishImperial.java
index 743beeb..c6e65fb 100644
--- a/src/main/java/sevenUnits/unit/BritishImperial.java
+++ b/src/main/java/sevenUnits/unit/BritishImperial.java
@@ -16,6 +16,8 @@
  */
 package sevenUnits.unit;
 
+import sevenUnits.utils.NameSymbol;
+
 /**
  * A static utility class that contains units in the British Imperial system.
  * 
diff --git a/src/main/java/sevenUnits/unit/FunctionalUnit.java b/src/main/java/sevenUnits/unit/FunctionalUnit.java
index df457e4..720b0af 100644
--- a/src/main/java/sevenUnits/unit/FunctionalUnit.java
+++ b/src/main/java/sevenUnits/unit/FunctionalUnit.java
@@ -19,6 +19,7 @@ package sevenUnits.unit;
 import java.util.Objects;
 import java.util.function.DoubleUnaryOperator;
 
+import sevenUnits.utils.NameSymbol;
 import sevenUnits.utils.ObjectProduct;
 
 /**
diff --git a/src/main/java/sevenUnits/unit/FunctionalUnitlike.java b/src/main/java/sevenUnits/unit/FunctionalUnitlike.java
index 2ee9e19..d6046c0 100644
--- a/src/main/java/sevenUnits/unit/FunctionalUnitlike.java
+++ b/src/main/java/sevenUnits/unit/FunctionalUnitlike.java
@@ -19,6 +19,7 @@ package sevenUnits.unit;
 import java.util.function.DoubleFunction;
 import java.util.function.ToDoubleFunction;
 
+import sevenUnits.utils.NameSymbol;
 import sevenUnits.utils.ObjectProduct;
 
 /**
diff --git a/src/main/java/sevenUnits/unit/LinearUnit.java b/src/main/java/sevenUnits/unit/LinearUnit.java
index 25c2e2e..deefc9a 100644
--- a/src/main/java/sevenUnits/unit/LinearUnit.java
+++ b/src/main/java/sevenUnits/unit/LinearUnit.java
@@ -19,6 +19,7 @@ package sevenUnits.unit;
 import java.util.Objects;
 
 import sevenUnits.utils.DecimalComparison;
+import sevenUnits.utils.NameSymbol;
 import sevenUnits.utils.ObjectProduct;
 import sevenUnits.utils.UncertainDouble;
 
diff --git a/src/main/java/sevenUnits/unit/Metric.java b/src/main/java/sevenUnits/unit/Metric.java
index 3c4d291..78e3769 100644
--- a/src/main/java/sevenUnits/unit/Metric.java
+++ b/src/main/java/sevenUnits/unit/Metric.java
@@ -18,6 +18,7 @@ package sevenUnits.unit;
 
 import java.util.Set;
 
+import sevenUnits.utils.NameSymbol;
 import sevenUnits.utils.ObjectProduct;
 
 /**
diff --git a/src/main/java/sevenUnits/unit/MultiUnit.java b/src/main/java/sevenUnits/unit/MultiUnit.java
index 83cdb03..bc240e3 100644
--- a/src/main/java/sevenUnits/unit/MultiUnit.java
+++ b/src/main/java/sevenUnits/unit/MultiUnit.java
@@ -20,6 +20,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
+import sevenUnits.utils.NameSymbol;
 import sevenUnits.utils.ObjectProduct;
 
 /**
diff --git a/src/main/java/sevenUnits/unit/Unit.java b/src/main/java/sevenUnits/unit/Unit.java
index 005b6f7..9866e9c 100644
--- a/src/main/java/sevenUnits/unit/Unit.java
+++ b/src/main/java/sevenUnits/unit/Unit.java
@@ -22,6 +22,8 @@ import java.util.Objects;
 import java.util.function.DoubleUnaryOperator;
 
 import sevenUnits.utils.DecimalComparison;
+import sevenUnits.utils.NameSymbol;
+import sevenUnits.utils.Nameable;
 import sevenUnits.utils.ObjectProduct;
 
 /**
diff --git a/src/main/java/sevenUnits/unit/UnitDatabase.java b/src/main/java/sevenUnits/unit/UnitDatabase.java
index 18ac619..b029539 100644
--- a/src/main/java/sevenUnits/unit/UnitDatabase.java
+++ b/src/main/java/sevenUnits/unit/UnitDatabase.java
@@ -47,6 +47,8 @@ import java.util.regex.Pattern;
 import sevenUnits.utils.ConditionalExistenceCollections;
 import sevenUnits.utils.DecimalComparison;
 import sevenUnits.utils.ExpressionParser;
+import sevenUnits.utils.NameSymbol;
+import sevenUnits.utils.NamedObjectProduct;
 import sevenUnits.utils.ObjectProduct;
 import sevenUnits.utils.UncertainDouble;
 
@@ -1197,7 +1199,7 @@ public final class UnitDatabase {
 	 * @since 2019-03-14
 	 * @since v0.2.0
 	 */
-	private final Map<String, ObjectProduct<BaseDimension>> dimensions;
+	private final Map<String, NamedObjectProduct<BaseDimension>> dimensions;
 	
 	/**
 	 * A map mapping strings to units (including prefixes)
@@ -1313,9 +1315,16 @@ public final class UnitDatabase {
 	 */
 	public void addDimension(final String name,
 			final ObjectProduct<BaseDimension> dimension) {
-		this.dimensions.put(
-				Objects.requireNonNull(name, "name must not be null."),
-				Objects.requireNonNull(dimension, "dimension must not be null."));
+		Objects.requireNonNull(name, "name may not be null");
+		Objects.requireNonNull(dimension, "dimension may not be null");
+		if (dimension instanceof NamedObjectProduct) {
+			this.dimensions.put(name,
+					(NamedObjectProduct<BaseDimension>) dimension);
+		} else {
+			final NamedObjectProduct<BaseDimension> namedDimension = dimension
+					.withName(NameSymbol.ofName(name));
+			this.dimensions.put(name, namedDimension);
+		}
 	}
 	
 	/**
@@ -1367,7 +1376,7 @@ public final class UnitDatabase {
 				throw e;
 			}
 			
-			this.addDimension(name, dimension);
+			this.addDimension(name, dimension.withName(NameSymbol.ofName(name)));
 		}
 	}
 	
@@ -1463,7 +1472,7 @@ public final class UnitDatabase {
 					throw e;
 				}
 				
-				this.addUnit(name, unit);
+				this.addUnit(name, unit.withName(NameSymbol.ofName(name)));
 			}
 		}
 	}
@@ -1510,7 +1519,7 @@ public final class UnitDatabase {
 	 * @since 2019-04-13
 	 * @since v0.2.0
 	 */
-	public Map<String, ObjectProduct<BaseDimension>> dimensionMap() {
+	public Map<String, NamedObjectProduct<BaseDimension>> dimensionMap() {
 		return Collections.unmodifiableMap(this.dimensions);
 	}
 	
diff --git a/src/main/java/sevenUnits/unit/UnitPrefix.java b/src/main/java/sevenUnits/unit/UnitPrefix.java
index 308f4b0..bf9d1fd 100644
--- a/src/main/java/sevenUnits/unit/UnitPrefix.java
+++ b/src/main/java/sevenUnits/unit/UnitPrefix.java
@@ -21,6 +21,7 @@ import java.util.Optional;
 import java.util.Set;
 
 import sevenUnits.utils.DecimalComparison;
+import sevenUnits.utils.NameSymbol;
 
 /**
  * A prefix that can be applied to a {@code LinearUnit} to multiply it by some value
diff --git a/src/main/java/sevenUnits/unit/UnitValue.java b/src/main/java/sevenUnits/unit/UnitValue.java
index f6d18f8..339263d 100644
--- a/src/main/java/sevenUnits/unit/UnitValue.java
+++ b/src/main/java/sevenUnits/unit/UnitValue.java
@@ -19,6 +19,8 @@ package sevenUnits.unit;
 import java.util.Objects;
 import java.util.Optional;
 
+import sevenUnits.utils.NameSymbol;
+
 /**
  * A value expressed in a unit.
  * 
diff --git a/src/main/java/sevenUnits/unit/Unitlike.java b/src/main/java/sevenUnits/unit/Unitlike.java
index d2dcbbb..68de2c2 100644
--- a/src/main/java/sevenUnits/unit/Unitlike.java
+++ b/src/main/java/sevenUnits/unit/Unitlike.java
@@ -22,6 +22,8 @@ import java.util.Objects;
 import java.util.function.DoubleFunction;
 import java.util.function.ToDoubleFunction;
 
+import sevenUnits.utils.NameSymbol;
+import sevenUnits.utils.Nameable;
 import sevenUnits.utils.ObjectProduct;
 
 /**
diff --git a/src/main/java/sevenUnits/unit/UnitlikeValue.java b/src/main/java/sevenUnits/unit/UnitlikeValue.java
index edc13ca..26354b1 100644
--- a/src/main/java/sevenUnits/unit/UnitlikeValue.java
+++ b/src/main/java/sevenUnits/unit/UnitlikeValue.java
@@ -18,6 +18,8 @@ package sevenUnits.unit;
 
 import java.util.Optional;
 
+import sevenUnits.utils.NameSymbol;
+
 /**
  *
  * @since 2020-09-07
diff --git a/src/main/java/sevenUnits/unit/NameSymbol.java b/src/main/java/sevenUnits/utils/NameSymbol.java
index 3e26138..aea274b 100644
--- a/src/main/java/sevenUnits/unit/NameSymbol.java
+++ b/src/main/java/sevenUnits/utils/NameSymbol.java
@@ -14,7 +14,7 @@
  * You should have received a copy of the GNU Affero General Public License
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
-package sevenUnits.unit;
+package sevenUnits.utils;
 
 import java.util.Arrays;
 import java.util.Collections;
@@ -277,4 +277,23 @@ public final class NameSymbol {
 		// if primaryName is empty, otherNames must also be empty
 		return this.primaryName.isEmpty() && this.symbol.isEmpty();
 	}
+	
+	/**
+	 * @return a short version of this NameSymbol (defaults to symbol instead of
+	 *         primary name)
+	 * @since 2022-02-26
+	 */
+	public String shortName() {
+		return this.symbol.or(this::getPrimaryName).orElse("EMPTY");
+	}
+	
+	@Override
+	public String toString() {
+		if (this.isEmpty())
+			return "NameSymbol.EMPTY";
+		else if (this.primaryName.isPresent() && this.symbol.isPresent())
+			return this.primaryName + " (" + this.symbol + ")";
+		else
+			return this.primaryName.orElseGet(this.symbol::orElseThrow);
+	}
 }
\ No newline at end of file
diff --git a/src/main/java/sevenUnits/unit/Nameable.java b/src/main/java/sevenUnits/utils/Nameable.java
index ed23687..3cfc05a 100644
--- a/src/main/java/sevenUnits/unit/Nameable.java
+++ b/src/main/java/sevenUnits/utils/Nameable.java
@@ -14,7 +14,7 @@
  * You should have received a copy of the GNU Affero General Public License
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
-package sevenUnits.unit;
+package sevenUnits.utils;
 
 import java.util.Optional;
 import java.util.Set;
diff --git a/src/main/java/sevenUnits/utils/NamedObjectProduct.java b/src/main/java/sevenUnits/utils/NamedObjectProduct.java
index 514f0b1..9c3079c 100644
--- a/src/main/java/sevenUnits/utils/NamedObjectProduct.java
+++ b/src/main/java/sevenUnits/utils/NamedObjectProduct.java
@@ -18,9 +18,6 @@ package sevenUnits.utils;
 
 import java.util.Map;
 
-import sevenUnits.unit.NameSymbol;
-import sevenUnits.unit.Nameable;
-
 /**
  * An ObjectProduct with name(s) and/or a symbol. Can be created with the
  * {@link ObjectProduct#withName} method.
@@ -43,4 +40,8 @@ public class NamedObjectProduct<T> extends ObjectProduct<T>
 		return this.nameSymbol;
 	}
 	
+	@Override
+	public String toString() {
+		return this.nameSymbol.toString() + ", " + super.toString();
+	}
 }
diff --git a/src/main/java/sevenUnits/utils/ObjectProduct.java b/src/main/java/sevenUnits/utils/ObjectProduct.java
index d4f88b9..926ce10 100644
--- a/src/main/java/sevenUnits/utils/ObjectProduct.java
+++ b/src/main/java/sevenUnits/utils/ObjectProduct.java
@@ -26,8 +26,6 @@ import java.util.Objects;
 import java.util.Set;
 import java.util.function.Function;
 
-import sevenUnits.unit.NameSymbol;
-
 /**
  * An immutable product of multiple objects of a type, such as base units. The
  * objects can be multiplied and exponentiated.
@@ -246,7 +244,9 @@ public class ObjectProduct<T> {
 	 */
 	@Override
 	public String toString() {
-		return this.toString(Object::toString);
+		return this.toString(o -> o instanceof Nameable
+				? ((Nameable) o).getNameSymbol().shortName()
+				: o.toString());
 	}
 	
 	/**
diff --git a/src/main/java/sevenUnitsGUI/Presenter.java b/src/main/java/sevenUnitsGUI/Presenter.java
index 23a631d..be02364 100644
--- a/src/main/java/sevenUnitsGUI/Presenter.java
+++ b/src/main/java/sevenUnitsGUI/Presenter.java
@@ -19,17 +19,26 @@ package sevenUnitsGUI;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
+import java.util.Collection;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.OptionalDouble;
 import java.util.Scanner;
+import java.util.Set;
 import java.util.function.Function;
 import java.util.function.Predicate;
 import java.util.stream.Collectors;
 
 import sevenUnits.ProgramInfo;
 import sevenUnits.unit.BaseDimension;
+import sevenUnits.unit.BritishImperial;
+import sevenUnits.unit.Metric;
 import sevenUnits.unit.Unit;
 import sevenUnits.unit.UnitDatabase;
 import sevenUnits.unit.UnitPrefix;
+import sevenUnits.unit.UnitValue;
 import sevenUnits.utils.ObjectProduct;
 import sevenUnits.utils.UncertainDouble;
 
@@ -40,6 +49,44 @@ import sevenUnits.utils.UncertainDouble;
  * @since 2021-12-15
  */
 public final class Presenter {
+	/** The default place where settings are stored. */
+	private static final String DEFAULT_SETTINGS_FILEPATH = "settings.txt";
+	/** The default place where units are stored. */
+	private static final String DEFAULT_UNITS_FILEPATH = "/unitsfile.txt";
+	/** The default place where dimensions are stored. */
+	private static final String DEFAULT_DIMENSIONS_FILEPATH = "/dimensionfile.txt";
+	/** The default place where exceptions are stored. */
+	private static final String DEFAULT_EXCEPTIONS_FILEPATH = "/metric_exceptions.txt";
+	
+	/**
+	 * Adds default units and dimensions to a database.
+	 * 
+	 * @param database database to add to
+	 * @since 2019-04-14
+	 * @since v0.2.0
+	 */
+	private static void addDefaults(final UnitDatabase database) {
+		database.addUnit("metre", Metric.METRE);
+		database.addUnit("kilogram", Metric.KILOGRAM);
+		database.addUnit("gram", Metric.KILOGRAM.dividedBy(1000));
+		database.addUnit("second", Metric.SECOND);
+		database.addUnit("ampere", Metric.AMPERE);
+		database.addUnit("kelvin", Metric.KELVIN);
+		database.addUnit("mole", Metric.MOLE);
+		database.addUnit("candela", Metric.CANDELA);
+		database.addUnit("bit", Metric.BIT);
+		database.addUnit("unit", Metric.ONE);
+		// nonlinear units - must be loaded manually
+		database.addUnit("tempCelsius", Metric.CELSIUS);
+		database.addUnit("tempFahrenheit", BritishImperial.FAHRENHEIT);
+		
+		// load initial dimensions
+		database.addDimension("LENGTH", Metric.Dimensions.LENGTH);
+		database.addDimension("MASS", Metric.Dimensions.MASS);
+		database.addDimension("TIME", Metric.Dimensions.TIME);
+		database.addDimension("TEMPERATURE", Metric.Dimensions.TEMPERATURE);
+	}
+	
 	/**
 	 * @return text in About file
 	 * @since 2022-02-19
@@ -86,6 +133,25 @@ public final class Presenter {
 	}
 	
 	/**
+	 * Accepts a collection and returns a set with the unique elements in that
+	 * collection
+	 *
+	 * @param <E>        type of element in collection
+	 * @param collection collection to uniquify
+	 * @return unique collection
+	 * @since 2022-02-26
+	 */
+	private static <E> Set<E> unique(Collection<E> collection) {
+		final Set<E> uniqueSet = new HashSet<>();
+		for (final E e : collection) {
+			if (!uniqueSet.contains(e)) {
+				uniqueSet.add(e);
+			}
+		}
+		return uniqueSet;
+	}
+	
+	/**
 	 * @return {@code line} with any comments removed.
 	 * @since 2021-03-13
 	 */
@@ -127,6 +193,13 @@ public final class Presenter {
 	private Predicate<List<UnitPrefix>> prefixRepetitionRule;
 	
 	/**
+	 * The set of units that is considered neither metric nor nonmetric for the
+	 * purposes of the metric-imperial one-way conversion. These units are
+	 * included in both From and To, even if One Way Conversion is enabled.
+	 */
+	private final Set<String> metricExceptions;
+	
+	/**
 	 * If this is true, views that show units as a list will have metric units
 	 * removed from the From unit list and imperial/USC units removed from the To
 	 * unit list.
@@ -148,20 +221,43 @@ public final class Presenter {
 	public Presenter(View view) {
 		this.view = view;
 		this.database = new UnitDatabase();
+		addDefaults(this.database);
+		
+		// load units and prefixes
+		try (final InputStream units = inputStream(DEFAULT_UNITS_FILEPATH)) {
+			this.database.loadUnitsFromStream(units);
+		} catch (final IOException e) {
+			throw new AssertionError("Loading of unitsfile.txt failed.", e);
+		}
+		
+		// load dimensions
+		try (final InputStream dimensions = inputStream(
+				DEFAULT_DIMENSIONS_FILEPATH)) {
+			this.database.loadDimensionsFromStream(dimensions);
+		} catch (final IOException e) {
+			throw new AssertionError("Loading of dimensionfile.txt failed.", e);
+		}
+		
+		// load metric exceptions
+		try {
+			this.metricExceptions = new HashSet<>();
+			try (InputStream exceptions = inputStream(DEFAULT_EXCEPTIONS_FILEPATH);
+					Scanner scanner = new Scanner(exceptions)) {
+				while (scanner.hasNextLine()) {
+					final String line = Presenter
+							.withoutComments(scanner.nextLine());
+					if (!line.isBlank()) {
+						this.metricExceptions.add(line);
+					}
+				}
+			}
+		} catch (final IOException e) {
+			throw new AssertionError("Loading of metric_exceptions.txt failed.",
+					e);
+		}
 	}
 	
 	/**
-	 * Sets the dimension of the view's From and To units.
-	 * 
-	 * @throws UnsupportedOperationException if the view does not support
-	 *                                       unit-based conversion (does not
-	 *                                       implement
-	 *                                       {@link UnitConversionView})
-	 * @since 2021-12-15
-	 */
-	public void applyDimensionFilter() {}
-	
-	/**
 	 * Gets settings from the view and applies them to both view and presenter.
 	 * 
 	 * @since 2021-12-15
@@ -190,7 +286,52 @@ public final class Presenter {
 	 *                                       {@link UnitConversionView})
 	 * @since 2021-12-15
 	 */
-	public void convertUnits() {}
+	public void convertUnits() {
+		if (this.view instanceof UnitConversionView) {
+			final UnitConversionView ucview = (UnitConversionView) this.view;
+			
+			final Optional<Unit> fromUnitOptional = ucview.getFromSelection();
+			final Optional<Unit> toUnitOptional = ucview.getToSelection();
+			final OptionalDouble valueOptional = ucview.getInputValue();
+			
+			// ensure everything is obtained
+			final Unit fromUnit, toUnit;
+			final double value;
+			if (fromUnitOptional.isPresent()) {
+				fromUnit = fromUnitOptional.orElseThrow();
+			} else {
+				this.view.showErrorMessage("Unit Conversion Error",
+						"Please specify a From unit");
+				return;
+			}
+			if (toUnitOptional.isPresent()) {
+				toUnit = toUnitOptional.orElseThrow();
+			} else {
+				this.view.showErrorMessage("Unit Conversion Error",
+						"Please specify a To unit");
+				return;
+			}
+			if (valueOptional.isPresent()) {
+				value = valueOptional.orElseThrow();
+			} else {
+				this.view.showErrorMessage("Unit Conversion Error",
+						"Please specify a valid value");
+				return;
+			}
+			
+			if (!fromUnit.canConvertTo(toUnit))
+				throw new AssertionError(
+						"From and To units incompatible (should be impossible)");
+			
+			// convert!
+			final UnitValue initialValue = UnitValue.of(fromUnit, value);
+			final UnitValue converted = initialValue.convertTo(toUnit);
+			ucview.showUnitConversionOutput(
+					String.format("%s = %s", initialValue, converted));
+		} else
+			throw new UnsupportedOperationException(
+					"This function can only be called when the view is a UnitConversionView.");
+	}
 	
 	/**
 	 * Loads settings from the user's settings file and applies them to the view.
@@ -199,6 +340,21 @@ public final class Presenter {
 	 */
 	public void loadSettings() {}
 	
+	/**
+	 * Completes creation of the presenter. This part of the initialization
+	 * depends on the view's functions, so it cannot be run if the components
+	 * they depend on are not created yet.
+	 * 
+	 * @since 2022-02-26
+	 */
+	public void postViewInitialize() {
+		// unit conversion specific stuff
+		if (this.view instanceof UnitConversionView) {
+			final UnitConversionView ucview = (UnitConversionView) this.view;
+			ucview.setDimensions(unique(this.database.dimensionMap().values()));
+		}
+	}
+	
 	void prefixSelected() {}
 	
 	/**
@@ -227,4 +383,26 @@ public final class Presenter {
 	}
 	
 	void unitNameSelected() {}
+	
+	/**
+	 * Updates the view's From and To units, if it has some
+	 * 
+	 * @since 2021-12-15
+	 */
+	public void updateView() {
+		if (this.view instanceof UnitConversionView) {
+			final UnitConversionView ucview = (UnitConversionView) this.view;
+			final ObjectProduct<BaseDimension> viewDimension = ucview
+					.getSelectedDimension().orElseThrow();
+			
+			final Set<Unit> units = this.database
+					.unitMapPrefixless(this.showDuplicateUnits).entrySet().stream()
+					.map(Map.Entry::getValue)
+					.filter(u -> viewDimension.equals(u.getDimension()))
+					.collect(Collectors.toSet());
+			
+			ucview.setFromUnits(units);
+			ucview.setToUnits(units);
+		}
+	}
 }
diff --git a/src/main/java/sevenUnitsGUI/TabbedView.java b/src/main/java/sevenUnitsGUI/TabbedView.java
index e92b661..c3a05e2 100644
--- a/src/main/java/sevenUnitsGUI/TabbedView.java
+++ b/src/main/java/sevenUnitsGUI/TabbedView.java
@@ -28,6 +28,7 @@ import java.util.Collections;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
 import java.util.Optional;
+import java.util.OptionalDouble;
 import java.util.Set;
 
 import javax.swing.BorderFactory;
@@ -212,7 +213,7 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 			this.dimensionSelector = new JComboBox<>();
 			inBetweenPanel.add(this.dimensionSelector, BorderLayout.PAGE_START);
 			this.dimensionSelector
-					.addItemListener(e -> this.presenter.applyDimensionFilter());
+					.addItemListener(e -> this.presenter.updateView());
 			
 			final JLabel arrowLabel = new JLabel("-->");
 			inBetweenPanel.add(arrowLabel, BorderLayout.CENTER);
@@ -326,9 +327,9 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 		this.masterPane.setMnemonicAt(5, KeyEvent.VK_S);
 		
 		// ============ FINALIZE CREATION OF VIEW ============
+		this.presenter.postViewInitialize();
 		this.frame.pack();
 		this.frame.setVisible(true);
-		
 	}
 	
 	/**
@@ -541,8 +542,13 @@ final class TabbedView implements ExpressionConversionView, UnitConversionView {
 	}
 	
 	@Override
-	public String getInputValue() {
-		return this.valueInput.getText();
+	public OptionalDouble getInputValue() {
+		final String text = this.valueInput.getText();
+		try {
+			return OptionalDouble.of(Double.parseDouble(text));
+		} catch (final NumberFormatException e) {
+			return OptionalDouble.empty();
+		}
 	}
 	
 	@Override
diff --git a/src/main/java/sevenUnitsGUI/UnitConversionView.java b/src/main/java/sevenUnitsGUI/UnitConversionView.java
index 5fd5a82..e411a44 100644
--- a/src/main/java/sevenUnitsGUI/UnitConversionView.java
+++ b/src/main/java/sevenUnitsGUI/UnitConversionView.java
@@ -17,6 +17,7 @@
 package sevenUnitsGUI;
 
 import java.util.Optional;
+import java.util.OptionalDouble;
 import java.util.Set;
 
 import sevenUnits.unit.BaseDimension;
@@ -48,7 +49,7 @@ public interface UnitConversionView extends View {
 	 *         string provided by the user)
 	 * @since 2021-12-15
 	 */
-	String getInputValue();
+	OptionalDouble getInputValue();
 	
 	/**
 	 * @return selected dimension
diff --git a/src/main/java/sevenUnitsGUI/ViewBot.java b/src/main/java/sevenUnitsGUI/ViewBot.java
index 0c0d189..bc5302b 100644
--- a/src/main/java/sevenUnitsGUI/ViewBot.java
+++ b/src/main/java/sevenUnitsGUI/ViewBot.java
@@ -20,6 +20,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.OptionalDouble;
 import java.util.Set;
 
 import sevenUnits.unit.BaseDimension;
@@ -47,7 +48,7 @@ final class ViewBot implements UnitConversionView, ExpressionConversionView {
 	/**
 	 * The user-provided string representing the value in {@code fromSelection}
 	 */
-	private String inputValue;
+	private OptionalDouble inputValue;
 	/** The unit selected in the From selection */
 	private Optional<Unit> fromSelection;
 	/** The unit selected in the To selection */
@@ -102,7 +103,7 @@ final class ViewBot implements UnitConversionView, ExpressionConversionView {
 	}
 	
 	@Override
-	public String getInputValue() {
+	public OptionalDouble getInputValue() {
 		return this.inputValue;
 	}
 	
@@ -190,7 +191,7 @@ final class ViewBot implements UnitConversionView, ExpressionConversionView {
 	 * @param inputValue the inputValue to set
 	 * @since 2022-01-29
 	 */
-	public void setInputValue(String inputValue) {
+	public void setInputValue(OptionalDouble inputValue) {
 		this.inputValue = inputValue;
 	}
 	
diff --git a/src/test/java/sevenUnits/unit/UnitDatabaseTest.java b/src/test/java/sevenUnits/unit/UnitDatabaseTest.java
index 2276d7c..b8669cb 100644
--- a/src/test/java/sevenUnits/unit/UnitDatabaseTest.java
+++ b/src/test/java/sevenUnits/unit/UnitDatabaseTest.java
@@ -39,6 +39,7 @@ import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
 
+import sevenUnits.utils.NameSymbol;
 import sevenUnits.utils.UncertainDouble;
 
 /**
diff --git a/src/test/java/sevenUnits/unit/UnitTest.java b/src/test/java/sevenUnits/unit/UnitTest.java
index bb2e6a4..f174e7c 100644
--- a/src/test/java/sevenUnits/unit/UnitTest.java
+++ b/src/test/java/sevenUnits/unit/UnitTest.java
@@ -27,6 +27,7 @@ import java.util.concurrent.ThreadLocalRandom;
 import org.junit.jupiter.api.Test;
 
 import sevenUnits.utils.DecimalComparison;
+import sevenUnits.utils.NameSymbol;
 import sevenUnits.utils.UncertainDouble;
 
 /**
diff --git a/src/test/java/sevenUnitsGUI/PresenterTest.java b/src/test/java/sevenUnitsGUI/PresenterTest.java
index 3e7c2b5..ff1450b 100644
--- a/src/test/java/sevenUnitsGUI/PresenterTest.java
+++ b/src/test/java/sevenUnitsGUI/PresenterTest.java
@@ -21,14 +21,15 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.List;
 import java.util.Optional;
+import java.util.OptionalDouble;
 import java.util.Set;
 
 import org.junit.jupiter.api.Test;
 
 import sevenUnits.unit.BaseDimension;
 import sevenUnits.unit.Metric;
-import sevenUnits.unit.NameSymbol;
 import sevenUnits.unit.Unit;
+import sevenUnits.utils.NameSymbol;
 import sevenUnits.utils.NamedObjectProduct;
 
 /**
@@ -44,12 +45,12 @@ public final class PresenterTest {
 			Metric.Dimensions.VELOCITY.withName(NameSymbol.ofName("Velocity")));
 	
 	/**
-	 * Test for {@link Presenter#applyDimensionFilter()}
+	 * Test for {@link Presenter#updateView()}
 	 * 
 	 * @since 2022-02-12
 	 */
 	@Test
-	void testApplyDimensionFilter() {
+	void testUpdateView() {
 		// setup
 		final ViewBot viewBot = new ViewBot();
 		final Presenter presenter = new Presenter(viewBot);
@@ -61,7 +62,7 @@ public final class PresenterTest {
 				Optional.of(this.testDimensions.iterator().next()));
 		
 		// filter to length units only, then get the filtered sets of units
-		presenter.applyDimensionFilter();
+		presenter.updateView();
 		final Set<Unit> fromUnits = viewBot.getFromUnits();
 		final Set<Unit> toUnits = viewBot.getToUnits();
 		
@@ -118,7 +119,7 @@ public final class PresenterTest {
 		viewBot.setToUnits(this.testUnits);
 		viewBot.setFromSelection(Optional.of(Metric.METRE));
 		viewBot.setToSelection(Optional.of(Metric.KILOMETRE));
-		viewBot.setInputValue("10000.0");
+		viewBot.setInputValue(OptionalDouble.of(10000.0));
 		
 		// convert units
 		presenter.convertUnits();