New Density unit: Pounds per Gallon US

README.md

@@ -160,7 +160,7 @@ units and at least one Imperial unit.
 * Power: Watt [W], Kilowatt [kW], Megawatt [MW], BTU/hour [BTU/h], Horse Power [HP]
 * Specific heat: Joules per kilogram Kelvin [J/(kg·K)], Kilojoules per kilogram Kelvin [kJ/(kg·K)], BTU per pound
   Fahrenheit [BTU/(lb·°F)]
-* Density: Kilogram per cubic meter [kg/m³], Pound per cubic foot [lb/ft³], Pounds per cubic inch [lb/in³]
+* Density: Kilogram per cubic meter [kg/m³], Pound per cubic foot [lb/ft³], Pounds per cubic inch [lb/in³], Pounds per Gallon US [lb/gal_US]
 * Dynamic viscosity: Kilogram per meter second [kg/(m·s)], Pascal second [Pa·s], Poise [P]
 * Kinematic viscosity: Square meter per second [m²/s], Square foot per second [ft²/s]
 * Specific enthalpy: Joule per kilogram [J/kg], Kilojoule per kilogram [kJ/kg], BTU per pound [BTU/lb]

unitility-core/src/main/java/com/synerset/unitility/unitsystem/thermodynamic/Density.java

@@ -38,6 +38,14 @@ public static Density ofPoundPerCubicFoot(double value) {
         return new Density(value, DensityUnits.POUND_PER_CUBIC_FOOT);
     }
 
+    public static Density ofPoundPerCubicInch(double value) {
+        return new Density(value, DensityUnits.POUND_PER_CUBIC_INCH);
+    }
+
+    public static Density ofPoundPerGallonUS(double value) {
+        return new Density(value, DensityUnits.POUND_PER_GALLON_US);
+    }
+
     @Override
     public double getValue() {
         return value;
@@ -86,6 +94,14 @@ public Density toPoundPerCubicFoot() {
         return toUnit(DensityUnits.POUND_PER_CUBIC_FOOT);
     }
 
+    public Density toPoundPerCubicInch() {
+        return toUnit(DensityUnits.POUND_PER_CUBIC_INCH);
+    }
+
+    public Density toPoundPerGallonUS() {
+        return toUnit(DensityUnits.POUND_PER_GALLON_US);
+    }
+
     // Get value in target unit
     public double getInKilogramsPerCubicMeters() {
         return getInUnit(DensityUnits.KILOGRAM_PER_CUBIC_METER);
@@ -99,6 +115,10 @@ public double getInPoundsPerCubicInches() {
         return getInUnit(DensityUnits.POUND_PER_CUBIC_INCH);
     }
 
+    public double getInPoundsPerGallonUS() {
+        return getInUnit(DensityUnits.POUND_PER_GALLON_US);
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;

unitility-core/src/main/java/com/synerset/unitility/unitsystem/thermodynamic/DensityUnits.java

@@ -9,7 +9,8 @@ public enum DensityUnits implements DensityUnit {
 
     KILOGRAM_PER_CUBIC_METER("kg/m³", val -> val, val -> val),
     POUND_PER_CUBIC_FOOT("lb/ft³", val -> val * 16.0184633739599, val -> val / 16.0184633739599),
-    POUND_PER_CUBIC_INCH("lb/in³", val -> val / 0.000036127292218, val -> val * 0.000036127292218);
+    POUND_PER_CUBIC_INCH("lb/in³", val -> val / 0.000036127292218, val -> val * 0.000036127292218),
+    POUND_PER_GALLON_US("lb/gal_US", val -> val / 0.0083454063545262, val -> val * 0.0083454063545262);
 
     private final String symbol;
     private final DoubleUnaryOperator toBaseConverter;

unitility-core/src/test/java/com/synerset/unitility/unitsystem/thermodynamic/DensityTest.java

@@ -40,12 +40,32 @@ void shouldProperlyConvertKilogramsPerCubicMeterToPoundPerCubicInch() {
         Density actualInKilogramPerCubicMeter = actualInPoundsPerCubicInch.toBaseUnit();
 
         // Then
-        Density expectedInPoundsPerCubicInch = Density.of(0.0000433527506616, DensityUnits.POUND_PER_CUBIC_INCH);
+        Density expectedInPoundsPerCubicInch = Density.ofPoundPerCubicInch(0.0000433527506616);
         assertThat(actualInPoundsPerCubicInch.getValue()).isEqualTo(actualInPoundsPerCubicInchVal);
         assertThat(actualInPoundsPerCubicInch.getValue()).isEqualTo(expectedInPoundsPerCubicInch.getValue(), withPrecision(1E-16));
         assertThat(actualInKilogramPerCubicMeter.getValue()).isEqualTo(1.2, withPrecision(1E-16));
     }
 
+    @Test
+    @DisplayName("should convert kg/m³ to lb/gal_us and vice versa")
+    void shouldProperlyConvertKilogramsPerCubicMeterToPoundPerGallonUS() {
+        // Given
+        Density initialDensity = Density.ofKilogramPerCubicMeter(1000);
+
+        // When
+        Density actualInPoundsPerGallonUS = initialDensity.toUnit(DensityUnits.POUND_PER_GALLON_US);
+        double actualInPoundsPerGallonUSVal = initialDensity.getInPoundsPerGallonUS();
+        Density actualInKilogramPerCubicMeter = actualInPoundsPerGallonUS.toBaseUnit();
+        double actualInKilogramPerCubicMeterVal = actualInPoundsPerGallonUS.getInKilogramsPerCubicMeters();
+
+        // Then
+        Density expectedInPoundsPerGallonUS = Density.ofPoundPerGallonUS(8.3454063545262);
+        assertThat(actualInPoundsPerGallonUS.getValue()).isEqualTo(actualInPoundsPerGallonUSVal);
+        assertThat(actualInKilogramPerCubicMeter.getValue()).isEqualTo(actualInKilogramPerCubicMeterVal);
+        assertThat(actualInPoundsPerGallonUS.getValue()).isEqualTo(expectedInPoundsPerGallonUS.getValue(), withPrecision(1E-16));
+        assertThat(actualInKilogramPerCubicMeter.getValue()).isEqualTo(1000, withPrecision(1E-13));
+    }
+
     @Test
     @DisplayName("should have kg/m³ as base unit")
     void shouldHaveKilogramPerCubicMeterAsBaseUnit() {
@@ -68,6 +88,8 @@ void shouldReturnValidResultFromToAndGetInMethods() {
 
         // When
         Density actual = expected.toPoundPerCubicFoot()
+                .toPoundPerCubicInch()
+                .toPoundPerGallonUS()
                 .toKilogramPerCubicMeter();
 
         double actualValue = expected.getInKilogramsPerCubicMeters();