Fix potential resource leaks in Presenter

1 files changed, 250 insertions, 242 deletions

diff --git a/src/main/java/sevenUnitsGUI/Presenter.java b/src/main/java/sevenUnitsGUI/Presenter.java
index ff7e23c..9913e89 100644
--- a/src/main/java/sevenUnitsGUI/Presenter.java
+++ b/src/main/java/sevenUnitsGUI/Presenter.java
@@ -86,12 +86,11 @@ public final class Presenter {
 	 * </ul>
 	 */
 	static final String DEFAULT_LOCALE = "en";
-
+	
 	private static final List<String> LOCAL_LOCALES = List.of("en", "fr");
 	private static final Path USER_LOCALES_DIR = userConfigDir()
 			.resolve("SevenUnits").resolve("locales");
-
-
+	
 	/**
 	 * Adds default units and dimensions to a database.
 	 *
@@ -113,14 +112,14 @@ public final class Presenter {
 		// 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);
 	}
-
+	
 	private static String displayRuleToString(
 			Function<UncertainDouble, String> numberDisplayRule) {
 		if (numberDisplayRule instanceof FixedDecimals)
@@ -134,7 +133,7 @@ public final class Presenter {
 		else
 			return numberDisplayRule.toString();
 	}
-
+	
 	/**
 	 * Determines where to wrap {@code toWrap} with a max line length of
 	 * {@code maxLineLength}. If no good spot is found, returns -1.
@@ -149,7 +148,7 @@ public final class Presenter {
 		}
 		return -1;
 	}
-
+	
 	/**
 	 * Gets the text of a resource file as a set of strings (each one is one line
 	 * of the text).
@@ -161,7 +160,7 @@ public final class Presenter {
 	 */
 	private static List<String> getLinesFromResource(String filename) {
 		final List<String> lines = new ArrayList<>();
-
+		
 		try (var stream = inputStream(filename);
 				var scanner = new Scanner(stream)) {
 			while (scanner.hasNextLine()) {
@@ -171,10 +170,10 @@ public final class Presenter {
 			throw new AssertionError(
 					"Error occurred while loading file " + filename, e);
 		}
-
+		
 		return lines;
 	}
-
+	
 	/**
 	 * Gets an input stream for a resource file.
 	 *
@@ -186,7 +185,7 @@ public final class Presenter {
 	private static InputStream inputStream(String filepath) {
 		return Presenter.class.getResourceAsStream(filepath);
 	}
-
+	
 	/**
 	 * Convert a linear unit value to a string, where the number is rounded to
 	 * the nearest integer.
@@ -197,26 +196,26 @@ public final class Presenter {
 	private static String linearUnitValueIntToString(LinearUnitValue uv) {
 		return Long.toString(Math.round(uv.getValueExact())) + " " + uv.getUnit();
 	}
-
+	
 	private static Map.Entry<String, String> parseSettingLine(String line) {
 		final var equalsIndex = line.indexOf('=');
 		if (equalsIndex == -1)
 			throw new IllegalStateException(
 					"Settings file is malformed at line: " + line);
-
+		
 		final var param = line.substring(0, equalsIndex);
 		final var value = line.substring(equalsIndex + 1);
-
+		
 		return Map.entry(param, value);
 	}
-
+	
 	/** Gets a Path from a pathname in the config file. */
 	private static Path pathFromConfig(String pathname) {
 		return CONFIG_FILE.getParent().resolve(pathname);
 	}
-
+	
 	// ====== SETTINGS ======
-
+	
 	private static String searchRuleToString(
 			Function<Map.Entry<String, LinearUnit>, Map<String, LinearUnit>> searchRule) {
 		if (PrefixSearchRule.NO_PREFIXES.equals(searchRule))
@@ -228,7 +227,7 @@ public final class Presenter {
 		else
 			return searchRule.toString();
 	}
-
+	
 	/**
 	 * @return true iff a and b have any elements in common
 	 * @since 2022-04-19
@@ -241,7 +240,7 @@ public final class Presenter {
 		}
 		return false;
 	}
-
+	
 	private static Path userConfigDir() {
 		if (System.getProperty("os.name").startsWith("Windows")) {
 			final var envFolder = System.getenv("LOCALAPPDATA");
@@ -256,7 +255,7 @@ public final class Presenter {
 		else
 			return Path.of(envFolder);
 	}
-
+	
 	/**
 	 * @return {@code line} with any comments removed.
 	 * @since 2021-03-13
@@ -266,7 +265,7 @@ public final class Presenter {
 		final var index = line.indexOf('#');
 		return index == -1 ? line : line.substring(0, index);
 	}
-
+	
 	/**
 	 * Wraps a string, ensuring no line is longer than {@code maxLineLength}.
 	 *
@@ -291,23 +290,23 @@ public final class Presenter {
 		wrapped.append(remaining);
 		return wrapped.toString();
 	}
-
+	
 	/**
 	 * The view that this presenter communicates with
 	 */
 	private final View view;
-
+	
 	/**
 	 * The database that this presenter communicates with (effectively the model)
 	 */
 	final UnitDatabase database;
-
+	
 	/**
 	 * The rule used for parsing input numbers. Any number-string inputted into
 	 * this program will be parsed using this method. <b>Not implemented yet.</b>
 	 */
 	private Function<String, UncertainDouble> numberParsingRule;
-
+	
 	/**
 	 * The rule used for displaying the results of unit conversions. The result
 	 * of unit conversions will be put into this function, and the resulting
@@ -315,41 +314,41 @@ public final class Presenter {
 	 */
 	private Function<UncertainDouble, String> numberDisplayRule = StandardDisplayRules
 			.uncertaintyBased();
-
+	
 	/**
 	 * A predicate that determines whether or not a certain combination of
 	 * prefixes is allowed. If it returns false, a combination of prefixes will
 	 * not be allowed. Prefixes are put in the list from right to left.
 	 */
 	private Predicate<List<UnitPrefix>> prefixRepetitionRule = DefaultPrefixRepetitionRule.NO_RESTRICTION;
-
+	
 	/**
 	 * A rule that accepts a prefixless name-unit pair and returns a map mapping
 	 * names to prefixed versions of that unit (including the unit itself) that
 	 * should be searchable.
 	 */
 	private Function<Map.Entry<String, LinearUnit>, Map<String, LinearUnit>> searchRule = PrefixSearchRule.NO_PREFIXES;
-
+	
 	/**
 	 * 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;
-
+	
 	/** maps locale names (e.g. 'en') to key-text maps */
 	final Map<String, Map<String, String>> locales;
-
+	
 	/** name of locale in locales to use */
 	String userLocale;
-
+	
 	/**
 	 * 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.
 	 */
 	private boolean oneWayConversionEnabled = false;
-
+	
 	/**
 	 * If this is false, duplicate units and prefixes will be removed from the
 	 * unit view in views that show units as a list to choose from.
@@ -368,7 +367,7 @@ public final class Presenter {
 	private final Set<Path> customDimensionFiles = new HashSet<>();
 	/** Custom exception datafiles that will be loaded by {@link #reloadData} */
 	private final Set<Path> customExceptionFiles = new HashSet<>();
-
+	
 	/**
 	 * Creates a Presenter
 	 *
@@ -380,78 +379,40 @@ public final class Presenter {
 		this.view = view;
 		this.database = new UnitDatabase();
 		this.metricExceptions = new HashSet<>();
-
+		
 		this.locales = this.loadLocales();
 		this.userLocale = DEFAULT_LOCALE;
-
+		
 		// set default settings temporarily
 		if (Files.exists(CONFIG_FILE)) {
 			this.loadSettings(CONFIG_FILE);
 		}
-
+		
 		this.reloadData();
-
+		
 		// print out unit counts
 		System.out.println(this.loadStatMsg());
 	}
 	
-	/**
-	 * Clears then reloads all unit, prefix, dimension and exception data.
-	 */
-	public void reloadData() {
-		this.database.clear();
-		this.metricExceptions.clear();
-		addDefaults(this.database);
-		
-		if (this.useDefaultDatafiles) {
-			this.loadDefaultData();
+	private void addLocaleFile(Map<String, Map<String, String>> locales,
+			Path file) throws IOException {
+		final Map<String, String> locale = new HashMap<>();
+		final String fileName = file.getName(file.getNameCount() - 1).toString();
+		final String localeName = fileName.substring(0, fileName.length() - 4);
+		try (Stream<String> lines = Files.lines(file)) {
+			lines.forEach(line -> this.addLocaleLine(locale, line));
 		}
-		
-		this.customUnitFiles.forEach(
-				path -> this.handleLoadErrors(this.database.loadUnitsFile(path)));
-		this.customDimensionFiles.forEach(
-				path -> this.handleLoadErrors(this.database.loadDimensionFile(path)));
-		this.customExceptionFiles.forEach(this::loadExceptionFile);
+		locales.put(localeName, locale);
 	}
 	
-	/**
-	 * Load units, prefixes and dimensions from the default files.
-	 */
-	private void loadDefaultData() {
-		// load units and prefixes
-		try (final var units = inputStream(DEFAULT_UNITS_FILEPATH)) {
-			this.handleLoadErrors(this.database.loadUnitsFromStream(units));
-		} catch (final IOException e) {
-			throw new AssertionError("Loading of unitsfile.txt failed.", e);
-		}
-
-		// load dimensions
-		try (final var dimensions = inputStream(
-				DEFAULT_DIMENSIONS_FILEPATH)) {
-			this.handleLoadErrors(
-					this.database.loadDimensionsFromStream(dimensions));
-		} catch (final IOException e) {
-			throw new AssertionError("Loading of dimensionfile.txt failed.", e);
-		}
-
-		// load metric exceptions
-		try {
-			try (var exceptions = inputStream(DEFAULT_EXCEPTIONS_FILEPATH);
-					var scanner = new Scanner(exceptions)) {
-				while (scanner.hasNextLine()) {
-					final var 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);
-		}
+	private void addLocaleLine(Map<String, String> locale, String line) {
+		final String[] parts = line.split("=", 2);
+		if (parts.length < 2)
+			return;
+		
+		locale.put(parts[0], parts[1]);
 	}
-
+	
 	/**
 	 * Applies a search rule to an entry in a name-unit map.
 	 *
@@ -472,7 +433,7 @@ public final class Presenter {
 		}
 		return Stream.of(e);
 	}
-
+	
 	/**
 	 * Converts from the view's input expression to its output expression.
 	 * Displays an error message if any of the required fields are invalid.
@@ -489,10 +450,10 @@ public final class Presenter {
 			throw new UnsupportedOperationException(
 					"This function can only be called when the view is an ExpressionConversionView");
 		final var xcview = (ExpressionConversionView) this.view;
-
+		
 		final var fromExpression = xcview.getFromExpression();
 		final var toExpression = xcview.getToExpression();
-
+		
 		// expressions must not be empty
 		if (fromExpression.isEmpty()) {
 			this.view.showErrorMessage("Parse Error",
@@ -504,7 +465,7 @@ public final class Presenter {
 					"Please enter a unit expression in the To: box.");
 			return;
 		}
-
+		
 		final Optional<UnitConversionRecord> uc;
 		if (this.database.containsUnitSetName(toExpression)) {
 			uc = this.convertExpressionToNamedMultiUnit(fromExpression,
@@ -515,10 +476,10 @@ public final class Presenter {
 		} else {
 			uc = this.convertExpressionToExpression(fromExpression, toExpression);
 		}
-
+		
 		uc.ifPresent(xcview::showExpressionConversionOutput);
 	}
-
+	
 	/**
 	 * Converts a unit expression to another expression.
 	 *
@@ -547,7 +508,7 @@ public final class Presenter {
 					"Could not recognize text in To entry: " + e.getMessage());
 			return Optional.empty();
 		}
-
+		
 		// convert and show output
 		if (!from.getUnit().canConvertTo(to)) {
 			this.view.showErrorMessage("Conversion Error",
@@ -556,7 +517,7 @@ public final class Presenter {
 			return Optional.empty();
 		}
 		final UncertainDouble uncertainValue;
-
+		
 		// uncertainty is meaningless for non-linear units, so we will have
 		// to erase uncertainty information for them
 		if (to instanceof LinearUnit) {
@@ -566,14 +527,13 @@ public final class Presenter {
 			final var value = from.asUnitValue().convertTo(to).getValue();
 			uncertainValue = UncertainDouble.of(value, 0);
 		}
-
-		final var uc = UnitConversionRecord.valueOf(
-				fromExpression, toExpression, "",
-				this.numberDisplayRule.apply(uncertainValue));
+		
+		final var uc = UnitConversionRecord.valueOf(fromExpression, toExpression,
+				"", this.numberDisplayRule.apply(uncertainValue));
 		return Optional.of(uc);
-
+		
 	}
-
+	
 	/**
 	 * Convert an expression to a MultiUnit. If an error happened, it is shown to
 	 * the view and Optional.empty() is returned.
@@ -591,7 +551,7 @@ public final class Presenter {
 					"Could not recognize text in From entry: " + e.getMessage());
 			return Optional.empty();
 		}
-
+		
 		final List<LinearUnit> toUnits = new ArrayList<>(toExpressions.length);
 		for (final String toExpression : toExpressions) {
 			try {
@@ -610,7 +570,7 @@ public final class Presenter {
 				return Optional.empty();
 			}
 		}
-
+		
 		final List<LinearUnitValue> toValues;
 		try {
 			toValues = from.convertToMultiple(toUnits);
@@ -619,12 +579,12 @@ public final class Presenter {
 					"Invalid units separated by ';': " + e.getMessage());
 			return Optional.empty();
 		}
-
+		
 		final var toExpression = this.linearUnitValueSumToString(toValues);
 		return Optional.of(
 				UnitConversionRecord.valueOf(fromExpression, toExpression, "", ""));
 	}
-
+	
 	/**
 	 * Convert an expression to a MultiUnit with a name from the database. If an
 	 * error happened, it is shown to the view and Optional.empty() is returned.
@@ -642,7 +602,7 @@ public final class Presenter {
 					"Could not recognize text in From entry: " + e.getMessage());
 			return Optional.empty();
 		}
-
+		
 		final var toUnits = this.database.getUnitSet(toName);
 		final List<LinearUnitValue> toValues;
 		try {
@@ -652,12 +612,12 @@ public final class Presenter {
 					"Invalid units separated by ';': " + e.getMessage());
 			return Optional.empty();
 		}
-
+		
 		final var toExpression = this.linearUnitValueSumToString(toValues);
 		return Optional.of(
 				UnitConversionRecord.valueOf(fromExpression, toExpression, "", ""));
 	}
-
+	
 	/**
 	 * Converts from the view's input unit to its output unit. Displays an error
 	 * message if any of the required fields are invalid.
@@ -674,11 +634,11 @@ public final class Presenter {
 			throw new UnsupportedOperationException(
 					"This function can only be called when the view is a UnitConversionView.");
 		final var ucview = (UnitConversionView) this.view;
-
+		
 		final var fromUnitOptional = ucview.getFromSelection();
 		final var toUnitOptional = ucview.getToSelection();
 		final var inputValueString = ucview.getInputValue();
-
+		
 		// extract values from optionals
 		final String fromUnitString, toUnitString;
 		if (fromUnitOptional.isPresent()) {
@@ -695,11 +655,11 @@ public final class Presenter {
 					"Please specify a To unit");
 			return;
 		}
-
+		
 		// convert strings to data, checking if anything is invalid
 		final Unit fromUnit;
 		final UncertainDouble uncertainValue;
-
+		
 		if (this.database.containsUnitName(fromUnitString)) {
 			fromUnit = this.database.getUnit(fromUnitString);
 		} else
@@ -717,14 +677,13 @@ public final class Presenter {
 					this.convertUnitToUnit(fromUnitString, toUnitString,
 							inputValueString, fromUnit, toUnit, uncertainValue));
 		} else if (this.database.containsUnitSetName(toUnitString)) {
-			final var toMulti = this.database
-					.getUnitSet(toUnitString);
+			final var toMulti = this.database.getUnitSet(toUnitString);
 			ucview.showUnitConversionOutput(this.convertUnitToMulti(fromUnitString,
 					inputValueString, fromUnit, toMulti, uncertainValue));
 		} else
 			throw this.viewError("Nonexistent To unit: %s", toUnitString);
 	}
-
+	
 	private UnitConversionRecord convertUnitToMulti(String fromUnitString,
 			String inputValueString, Unit fromUnit, List<LinearUnit> toMulti,
 			UncertainDouble uncertainValue) {
@@ -733,7 +692,7 @@ public final class Presenter {
 				throw this.viewError("Could not convert between %s and %s",
 						fromUnit, toUnit);
 		}
-
+		
 		final LinearUnitValue initValue;
 		if (fromUnit instanceof LinearUnit) {
 			final var fromLinear = (LinearUnit) fromUnit;
@@ -742,22 +701,21 @@ public final class Presenter {
 			initValue = UnitValue.of(fromUnit, uncertainValue.value())
 					.convertToBase(NameSymbol.EMPTY);
 		}
-
-		final var converted = initValue
-				.convertToMultiple(toMulti);
+		
+		final var converted = initValue.convertToMultiple(toMulti);
 		final var toExpression = this.linearUnitValueSumToString(converted);
 		return UnitConversionRecord.valueOf(fromUnitString, toExpression,
 				inputValueString, "");
-
+		
 	}
-
+	
 	private UnitConversionRecord convertUnitToUnit(String fromUnitString,
 			String toUnitString, String inputValueString, Unit fromUnit,
 			Unit toUnit, UncertainDouble uncertainValue) {
 		if (!fromUnit.canConvertTo(toUnit))
 			throw this.viewError("Could not convert between %s and %s", fromUnit,
 					toUnit);
-
+			
 		// convert - we will need to erase uncertainty for non-linear units, so
 		// we need to treat linear and non-linear units differently
 		final String outputValueString;
@@ -767,21 +725,21 @@ public final class Presenter {
 			final var initialValue = LinearUnitValue.of(fromLinear,
 					uncertainValue);
 			final var converted = initialValue.convertTo(toLinear);
-
+			
 			outputValueString = this.numberDisplayRule.apply(converted.getValue());
 		} else {
 			final var initialValue = UnitValue.of(fromUnit,
 					uncertainValue.value());
 			final var converted = initialValue.convertTo(toUnit);
-
+			
 			outputValueString = this.numberDisplayRule
 					.apply(UncertainDouble.of(converted.getValue(), 0));
 		}
-
+		
 		return UnitConversionRecord.valueOf(fromUnitString, toUnitString,
 				inputValueString, outputValueString);
 	}
-
+	
 	/**
 	 * @return true iff duplicate units are shown in unit lists
 	 * @since 2022-03-30
@@ -790,39 +748,44 @@ public final class Presenter {
 	public boolean duplicatesShown() {
 		return this.showDuplicates;
 	}
-
+	
+	private String formatAboutText(Stream<String> rawLines) {
+		return rawLines.map(Presenter::withoutComments)
+				.collect(Collectors.joining("\n"))
+				.replaceAll("\\[VERSION\\]", ProgramInfo.VERSION.toString())
+				.replaceAll("\\[LOADSTATS\\]", wrapString(this.loadStatMsg(), 72));
+	}
+	
 	/**
 	 * @return text in About file
 	 * @since 2022-02-19
 	 * @since v0.4.0
 	 */
 	public String getAboutText() {
-		final Path customFilepath = Presenter.pathFromConfig(
-				"about/" + this.userLocale + ".txt");
+		final Path customFilepath = Presenter
+				.pathFromConfig("about/" + this.userLocale + ".txt");
 		if (Files.exists(customFilepath)) {
-			try {
-				return formatAboutText(Files.lines(customFilepath));
-			} catch (IOException e) {
-				final String filename = String.format("/about/%s.txt", this.userLocale);
-				return formatAboutText(Presenter.getLinesFromResource(filename).stream());
+			try (Stream<String> lines = Files.lines(customFilepath)) {
+				return this.formatAboutText(lines);
+			} catch (final IOException e) {
+				final String filename = String.format("/about/%s.txt",
+						this.userLocale);
+				return this.formatAboutText(
+						Presenter.getLinesFromResource(filename).stream());
 			}
 		} else if (LOCAL_LOCALES.contains(this.userLocale)) {
-			final String filename = String.format("/about/%s.txt", this.userLocale);
-			return formatAboutText(Presenter.getLinesFromResource(filename).stream());
+			final String filename = String.format("/about/%s.txt",
+					this.userLocale);
+			return this.formatAboutText(
+					Presenter.getLinesFromResource(filename).stream());
 		} else {
 			final String filename = String.format("/about/%s.txt", DEFAULT_LOCALE);
-			return formatAboutText(Presenter.getLinesFromResource(filename).stream());
+			return this.formatAboutText(
+					Presenter.getLinesFromResource(filename).stream());
 		}
 		
 	}
 	
-	private String formatAboutText(Stream<String> rawLines) {
-		return rawLines
-				.map(Presenter::withoutComments).collect(Collectors.joining("\n"))
-				.replaceAll("\\[VERSION\\]", ProgramInfo.VERSION.toString())
-				.replaceAll("\\[LOADSTATS\\]", wrapString(this.loadStatMsg(), 72));
-	}
-
 	/**
 	 * @return set of all locales available to select
 	 * @since 2025-02-21
@@ -831,7 +794,7 @@ public final class Presenter {
 	public Set<String> getAvailableLocales() {
 		return this.locales.keySet();
 	}
-
+	
 	/**
 	 * Gets a name for this dimension using the database
 	 *
@@ -847,7 +810,7 @@ public final class Presenter {
 				.filter(d -> d.equals(dimension)).findAny().map(Nameable::getName)
 				.orElse(dimension.toString(Nameable::getName));
 	}
-
+	
 	/**
 	 * Gets the correct text for a provided ID. If this text is available in the
 	 * user's locale, that text is provided. Otherwise, text is taken from the
@@ -861,7 +824,7 @@ public final class Presenter {
 		final var defaultLocale = this.locales.get(DEFAULT_LOCALE);
 		return userLocale.getOrDefault(textID, defaultLocale.get(textID));
 	}
-
+	
 	/**
 	 * @return the rule that is used by this presenter to convert numbers into
 	 *         strings
@@ -871,7 +834,7 @@ public final class Presenter {
 	public Function<UncertainDouble, String> getNumberDisplayRule() {
 		return this.numberDisplayRule;
 	}
-
+	
 	/**
 	 * @return the rule that is used by this presenter to convert strings into
 	 *         numbers
@@ -882,7 +845,7 @@ public final class Presenter {
 	private Function<String, UncertainDouble> getNumberParsingRule() {
 		return this.numberParsingRule;
 	}
-
+	
 	/**
 	 * @return the rule that determines whether a set of prefixes is valid
 	 * @since 2022-04-19
@@ -891,7 +854,7 @@ public final class Presenter {
 	public Predicate<List<UnitPrefix>> getPrefixRepetitionRule() {
 		return this.prefixRepetitionRule;
 	}
-
+	
 	/**
 	 * @return the rule that determines which units are prefixed
 	 * @since 2022-07-08
@@ -900,7 +863,7 @@ public final class Presenter {
 	public Function<Map.Entry<String, LinearUnit>, Map<String, LinearUnit>> getSearchRule() {
 		return this.searchRule;
 	}
-
+	
 	/**
 	 * @return a search rule that shows all single prefixes
 	 * @since 2022-07-08
@@ -910,16 +873,16 @@ public final class Presenter {
 		return PrefixSearchRule.getCoherentOnlyRule(
 				new HashSet<>(this.database.prefixMap(true).values()));
 	}
-
+	
 	/**
 	 * @return user's selected locale
 	 * @since 2025-02-21
 	 * @since v1.0.0
 	 */
 	public String getUserLocale() {
-		return userLocale;
+		return this.userLocale;
 	}
-
+	
 	/**
 	 * @return the view associated with this presenter
 	 * @since 2022-04-19
@@ -928,7 +891,7 @@ public final class Presenter {
 	public View getView() {
 		return this.view;
 	}
-
+	
 	/**
 	 * Accepts a list of errors. If that list is non-empty, prints an error
 	 * message and alerts the user.
@@ -947,7 +910,7 @@ public final class Presenter {
 					errorMessage);
 		}
 	}
-
+	
 	/**
 	 * @return whether or not the provided unit is semi-metric (i.e. an
 	 *         exception)
@@ -964,7 +927,7 @@ public final class Presenter {
 						&& this.metricExceptions.contains(symbol.orElseThrow())
 				|| sharesAnyElements(this.metricExceptions, u.getOtherNames());
 	}
-
+	
 	/**
 	 * Convert a list of LinearUnitValues that you would get from a unit-set
 	 * conversion to a string. All but the last have their numbers rendered as
@@ -982,7 +945,43 @@ public final class Presenter {
 		return integerPart + " + " + this.numberDisplayRule.apply(last.getValue())
 				+ " " + last.getUnit();
 	}
-
+	
+	/**
+	 * Load units, prefixes and dimensions from the default files.
+	 */
+	private void loadDefaultData() {
+		// load units and prefixes
+		try (final var units = inputStream(DEFAULT_UNITS_FILEPATH)) {
+			this.handleLoadErrors(this.database.loadUnitsFromStream(units));
+		} catch (final IOException e) {
+			throw new AssertionError("Loading of unitsfile.txt failed.", e);
+		}
+		
+		// load dimensions
+		try (final var dimensions = inputStream(DEFAULT_DIMENSIONS_FILEPATH)) {
+			this.handleLoadErrors(
+					this.database.loadDimensionsFromStream(dimensions));
+		} catch (final IOException e) {
+			throw new AssertionError("Loading of dimensionfile.txt failed.", e);
+		}
+		
+		// load metric exceptions
+		try {
+			try (var exceptions = inputStream(DEFAULT_EXCEPTIONS_FILEPATH);
+					var scanner = new Scanner(exceptions)) {
+				while (scanner.hasNextLine()) {
+					final var 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);
+		}
+	}
+	
 	private void loadExceptionFile(Path exceptionFile) {
 		try (var lines = Files.lines(exceptionFile)) {
 			lines.map(Presenter::withoutComments)
@@ -993,54 +992,38 @@ public final class Presenter {
 							+ exceptionFile + "\": " + e.getLocalizedMessage());
 		}
 	}
-
+	
 	/**
 	 * Loads all available locales, including custom ones, into a map.
+	 *
 	 * @return map containing locales
 	 */
 	private Map<String, Map<String, String>> loadLocales() {
 		final Map<String, Map<String, String>> locales = new HashMap<>();
 		for (final String localeName : LOCAL_LOCALES) {
 			final Map<String, String> locale = new HashMap<>();
-			String filename = "/locales/" + localeName + ".txt";
-			getLinesFromResource(filename).forEach(line -> addLocaleLine(locale, line));
-			locales.put(localeName, locale);	
+			final String filename = "/locales/" + localeName + ".txt";
+			getLinesFromResource(filename)
+					.forEach(line -> this.addLocaleLine(locale, line));
+			locales.put(localeName, locale);
 		}
 		
 		if (Files.exists(USER_LOCALES_DIR)) {
-			try {
-				Files.list(USER_LOCALES_DIR).forEach(
-						localeFile -> {
-							try {
-								addLocaleFile(locales, localeFile);
-							} catch (IOException e) {
-								e.printStackTrace();
-							}
-						});
-			} catch (IOException e) {
+			try (Stream<Path> files = Files.list(USER_LOCALES_DIR)) {
+				files.forEach(localeFile -> {
+					try {
+						this.addLocaleFile(locales, localeFile);
+					} catch (final IOException e) {
+						e.printStackTrace();
+					}
+				});
+			} catch (final IOException e) {
 				e.printStackTrace();
 			}
 		}
 		return locales;
 	}
 	
-	private void addLocaleFile(Map<String, Map<String, String>> locales, Path file) throws IOException {
-		final Map<String, String> locale = new HashMap<>();
-		String fileName = file.getName(file.getNameCount()-1).toString();
-		String localeName = fileName.substring(0, fileName.length()-4);
-		Files.lines(file).forEach(line -> addLocaleLine(locale, line));
-		locales.put(localeName, locale);
-	}
-	
-	private void addLocaleLine(Map<String, String> locale, String line) {
-		String[] parts = line.split("=", 2);
-		if (parts.length < 2) {
-			return;
-		}
-			
-		locale.put(parts[0], parts[1]);
-	}
-
 	/**
 	 * Loads settings from the user's settings file and applies them to the
 	 * presenter.
@@ -1053,11 +1036,11 @@ public final class Presenter {
 		this.customDimensionFiles.clear();
 		this.customExceptionFiles.clear();
 		this.customUnitFiles.clear();
-
+		
 		for (final Map.Entry<String, String> setting : this
 				.settingsFromFile(settingsFile)) {
 			final var value = setting.getValue();
-
+			
 			switch (setting.getKey()) {
 			// set manually to avoid the unnecessary saving of the non-manual
 			// methods
@@ -1094,11 +1077,11 @@ public final class Presenter {
 				if (this.locales.containsKey(value)) {
 					this.userLocale = value;
 				} else {
-					System.err.printf(
-							"Warning: unrecognized locale \"%s\".%n", value);
+					System.err.printf("Warning: unrecognized locale \"%s\".%n",
+							value);
 					this.view.showErrorMessage("Unrecognized Locale",
 							"Could not find locale \"" + value
-							+ "\", resetting to default.");
+									+ "\", resetting to default.");
 				}
 				break;
 			default:
@@ -1107,12 +1090,12 @@ public final class Presenter {
 				break;
 			}
 		}
-
+		
 		if (this.view.getPresenter() != null) {
 			this.updateView();
 		}
 	}
-
+	
 	/**
 	 * @return a message showing how much stuff has been loaded
 	 * @since 2024-08-22
@@ -1120,30 +1103,36 @@ public final class Presenter {
 	 */
 	private String loadStatMsg() {
 		return this.getLocalizedText("load_stat_msg")
-				.replace("[u]", Integer.toString(
-						this.database.unitMapPrefixless(false).size()))
-				.replace("[un]", Integer.toString(
-						this.database.unitMapPrefixless(true).size()))
-				.replace("[b]", Long.toString(this.database.unitMapPrefixless(false)
-						.values().stream().filter(IS_FULL_BASE).count()))
-				.replace("[p]", Integer.toString(this.database.prefixMap(false).size()))
-				.replace("[pn]", Integer.toString(this.database.prefixMap(true).size()))
+				.replace("[u]",
+						Integer.toString(
+								this.database.unitMapPrefixless(false).size()))
+				.replace("[un]",
+						Integer
+								.toString(this.database.unitMapPrefixless(true).size()))
+				.replace("[b]",
+						Long.toString(this.database.unitMapPrefixless(false).values()
+								.stream().filter(IS_FULL_BASE).count()))
+				.replace("[p]",
+						Integer.toString(this.database.prefixMap(false).size()))
+				.replace("[pn]",
+						Integer.toString(this.database.prefixMap(true).size()))
 				.replace("[s]", Integer.toString(this.database.unitSetMap().size()))
-				.replace("[d]", Integer.toString(this.database.dimensionMap().size()));
+				.replace("[d]",
+						Integer.toString(this.database.dimensionMap().size()));
 	}
-
+	
 	/**
 	 * @return true iff the One-Way Conversion feature is available (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)
-	 *
+	 * 
 	 * @since 2022-03-30
 	 * @since v0.4.0
 	 */
 	public boolean oneWayConversionEnabled() {
 		return this.oneWayConversionEnabled;
 	}
-
+	
 	/**
 	 * Completes creation of the presenter. This part of the initialization
 	 * depends on the view's functions, so it cannot be run if the components
@@ -1158,14 +1147,13 @@ public final class Presenter {
 			final var ucview = (UnitConversionView) this.view;
 			ucview.setDimensionNames(this.database.dimensionMap().keySet());
 		}
-
+		
 		this.updateView();
 		this.view.updateText();
 	}
-
+	
 	void prefixSelected() {
-		final var selectedPrefixName = this.view
-				.getViewedPrefixName();
+		final var selectedPrefixName = this.view.getViewedPrefixName();
 		final Optional<UnitPrefix> selectedPrefix = selectedPrefixName
 				.map(name -> this.database.containsPrefixName(name)
 						? this.database.getPrefix(name)
@@ -1174,7 +1162,26 @@ public final class Presenter {
 				.ifPresent(prefix -> this.view.showPrefix(prefix.getNameSymbol(),
 						String.valueOf(prefix.getMultiplier())));
 	}
-
+	
+	/**
+	 * Clears then reloads all unit, prefix, dimension and exception data.
+	 */
+	public void reloadData() {
+		this.database.clear();
+		this.metricExceptions.clear();
+		addDefaults(this.database);
+		
+		if (this.useDefaultDatafiles) {
+			this.loadDefaultData();
+		}
+		
+		this.customUnitFiles.forEach(
+				path -> this.handleLoadErrors(this.database.loadUnitsFile(path)));
+		this.customDimensionFiles.forEach(path -> this
+				.handleLoadErrors(this.database.loadDimensionFile(path)));
+		this.customExceptionFiles.forEach(this::loadExceptionFile);
+	}
+	
 	/**
 	 * Saves the presenter's current settings to the config file, creating it if
 	 * it doesn't exist.
@@ -1192,10 +1199,10 @@ public final class Presenter {
 				return false;
 			}
 		}
-
+		
 		return this.writeSettings(CONFIG_FILE);
 	}
-
+	
 	private void setDisplayRuleFromString(String ruleString) {
 		final var tokens = ruleString.split(" ");
 		switch (tokens[0]) {
@@ -1216,7 +1223,7 @@ public final class Presenter {
 			break;
 		}
 	}
-
+	
 	/**
 	 * @param numberDisplayRule the new rule that will be used by this presenter
 	 *                          to convert numbers into strings
@@ -1227,7 +1234,7 @@ public final class Presenter {
 			Function<UncertainDouble, String> numberDisplayRule) {
 		this.numberDisplayRule = numberDisplayRule;
 	}
-
+	
 	/**
 	 * @param numberParsingRule the new rule that will be used by this presenter
 	 *                          to convert strings into numbers
@@ -1239,7 +1246,7 @@ public final class Presenter {
 			Function<String, UncertainDouble> numberParsingRule) {
 		this.numberParsingRule = numberParsingRule;
 	}
-
+	
 	/**
 	 * @param oneWayConversionEnabled whether not one-way conversion should be
 	 *                                enabled
@@ -1251,7 +1258,7 @@ public final class Presenter {
 		this.oneWayConversionEnabled = oneWayConversionEnabled;
 		this.updateView();
 	}
-
+	
 	/**
 	 * @param prefixRepetitionRule the rule that determines whether a set of
 	 *                             prefixes is valid
@@ -1263,7 +1270,7 @@ public final class Presenter {
 		this.prefixRepetitionRule = prefixRepetitionRule;
 		this.database.setPrefixRepetitionRule(prefixRepetitionRule);
 	}
-
+	
 	/**
 	 * @param searchRule A rule that accepts a prefixless name-unit pair and
 	 *                   returns a map mapping names to prefixed versions of that
@@ -1276,7 +1283,7 @@ public final class Presenter {
 			Function<Map.Entry<String, LinearUnit>, Map<String, LinearUnit>> searchRule) {
 		this.searchRule = searchRule;
 	}
-
+	
 	private void setSearchRuleFromString(String ruleString) {
 		switch (ruleString) {
 		case "NO_PREFIXES":
@@ -1294,7 +1301,7 @@ public final class Presenter {
 					ruleString);
 		}
 	}
-
+	
 	/**
 	 * @param showDuplicateUnits whether or not duplicate units should be shown
 	 * @since 2022-03-30
@@ -1304,7 +1311,7 @@ public final class Presenter {
 		this.showDuplicates = showDuplicateUnits;
 		this.updateView();
 	}
-
+	
 	private List<Map.Entry<String, String>> settingsFromFile(Path settingsFile) {
 		try (var lines = Files.lines(settingsFile)) {
 			return lines.map(Presenter::withoutComments)
@@ -1318,17 +1325,18 @@ public final class Presenter {
 	}
 	
 	/**
-	 * Sets whether or not the default datafiles will be loaded.
-	 * This method automatically updates the view's units.
+	 * Sets whether or not the default datafiles will be loaded. This method
+	 * automatically updates the view's units.
 	 * 
-	 * @param useDefaultDatafiles whether or not default datafiles should be loaded
+	 * @param useDefaultDatafiles whether or not default datafiles should be
+	 *                            loaded
 	 */
 	public void setUseDefaultDatafiles(boolean useDefaultDatafiles) {
 		this.useDefaultDatafiles = useDefaultDatafiles;
 		this.reloadData();
 		this.updateView();
 	}
-
+	
 	/**
 	 * Sets the user's locale, updating the view.
 	 *
@@ -1338,7 +1346,7 @@ public final class Presenter {
 		this.userLocale = userLocale;
 		this.view.updateText();
 	}
-
+	
 	/**
 	 * Shows a unit in the unit viewer
 	 *
@@ -1355,7 +1363,7 @@ public final class Presenter {
 		final var unitType = UnitType.getType(u, this::isSemiMetric);
 		this.view.showUnit(nameSymbol, definition, dimensionString, unitType);
 	}
-
+	
 	/**
 	 * Runs whenever a unit name is selected in the unit viewer. Gets the
 	 * description of a unit and displays it.
@@ -1372,7 +1380,7 @@ public final class Presenter {
 						: null);
 		selectedUnit.ifPresent(this::showUnit);
 	}
-
+	
 	/**
 	 * Updates the view's From and To units, if it has some
 	 *
@@ -1383,20 +1391,20 @@ public final class Presenter {
 		if (this.view instanceof UnitConversionView) {
 			final var ucview = (UnitConversionView) this.view;
 			final var selectedDimensionName = ucview.getSelectedDimensionName();
-
+			
 			// load units & prefixes into viewers
 			this.view.setViewableUnitNames(
 					this.database.unitMapPrefixless(this.showDuplicates).keySet());
 			this.view.setViewablePrefixNames(
 					this.database.prefixMap(this.showDuplicates).keySet());
-
+			
 			// get From and To units
 			var fromUnits = this.database.unitMapPrefixless(this.showDuplicates)
 					.entrySet().stream();
 			var toUnits = this.database.unitMapPrefixless(this.showDuplicates)
 					.entrySet().stream();
 			var unitSets = this.database.unitSetMap().entrySet().stream();
-
+			
 			// filter by dimension, if one is selected
 			if (selectedDimensionName.isPresent()) {
 				final var viewDimension = this.database
@@ -1408,7 +1416,7 @@ public final class Presenter {
 				unitSets = unitSets.filter(us -> viewDimension
 						.equals(us.getValue().get(0).getDimension()));
 			}
-
+			
 			// filter by unit type, if desired
 			if (this.oneWayConversionEnabled) {
 				fromUnits = fromUnits.filter(u -> UnitType.getType(u.getValue(),
@@ -1419,7 +1427,7 @@ public final class Presenter {
 				unitSets = unitSets
 						.filter(us -> this.metricExceptions.contains(us.getKey()));
 			}
-
+			
 			// set unit names
 			ucview.setFromUnitNames(fromUnits.flatMap(this::applySearchRule)
 					.map(Map.Entry::getKey).collect(Collectors.toSet()));
@@ -1438,7 +1446,7 @@ public final class Presenter {
 	public boolean usingDefaultDatafiles() {
 		return this.useDefaultDatafiles;
 	}
-
+	
 	/**
 	 * @param message message to add
 	 * @param args    string formatting arguments for message
@@ -1451,7 +1459,7 @@ public final class Presenter {
 		return new AssertionError("View Programming Error (from " + this.view
 				+ "): " + String.format(message, args));
 	}
-
+	
 	/**
 	 * Saves the presenter's settings to the user settings file.
 	 *
@@ -1471,8 +1479,8 @@ public final class Presenter {
 					String.format("include_duplicates=%s\n", this.showDuplicates));
 			writer.write(String.format("search_prefix_rule=%s\n",
 					searchRuleToString(this.searchRule)));
-			writer.write(
-					String.format("use_default_datafiles=%s\n", this.useDefaultDatafiles));
+			writer.write(String.format("use_default_datafiles=%s\n",
+					this.useDefaultDatafiles));
 			writer.write(String.format("locale=%s\n", this.userLocale));
 			return true;
 		} catch (final IOException e) {