Added null checks to Unit's methods, including the new methods.

2 files changed, 15 insertions, 2 deletions

diff --git a/src/org/unitConverter/unit/FunctionalUnit.java b/src/org/unitConverter/unit/FunctionalUnit.java
index c2aae6d..e3db43a 100644
--- a/src/org/unitConverter/unit/FunctionalUnit.java
+++ b/src/org/unitConverter/unit/FunctionalUnit.java
@@ -16,6 +16,7 @@
  */
 package org.unitConverter.unit;
 
+import java.util.Objects;
 import java.util.function.DoubleUnaryOperator;
 
 /**
@@ -38,6 +39,8 @@ final class FunctionalUnit extends AbstractUnit {
 	 *            base.
 	 * @return a unit that uses the provided functions to convert.
 	 * @since 2019-05-22
+	 * @throws NullPointerException
+	 *             if any argument is null
 	 */
 	public static FunctionalUnit valueOf(final BaseUnit base, final DoubleUnaryOperator converterFrom,
 			final DoubleUnaryOperator converterTo) {
@@ -69,13 +72,15 @@ final class FunctionalUnit extends AbstractUnit {
 	 * @param converterTo
 	 *            function that accepts a value expressed in the unit and returns that value expressed in the unit's
 	 *            base.
+	 * @throws NullPointerException
+	 *             if any argument is null
 	 * @since 2019-05-22
 	 */
 	private FunctionalUnit(final BaseUnit base, final DoubleUnaryOperator converterFrom,
 			final DoubleUnaryOperator converterTo) {
 		super(base);
-		this.converterFrom = converterFrom;
-		this.converterTo = converterTo;
+		this.converterFrom = Objects.requireNonNull(converterFrom, "converterFrom must not be null.");
+		this.converterTo = Objects.requireNonNull(converterTo, "converterTo must not be null.");
 	}
 
 	@Override
diff --git a/src/org/unitConverter/unit/Unit.java b/src/org/unitConverter/unit/Unit.java
index 2ac107e..54f0ab5 100755
--- a/src/org/unitConverter/unit/Unit.java
+++ b/src/org/unitConverter/unit/Unit.java
@@ -48,6 +48,8 @@ public interface Unit {
 	 *            base.
 	 * @return a unit that uses the provided functions to convert.
 	 * @since 2019-05-22
+	 * @throws NullPointerException
+	 *             if any argument is null
 	 */
 	public static Unit fromConversionFunctions(final BaseUnit base, final DoubleUnaryOperator converterFrom,
 			final DoubleUnaryOperator converterTo) {
@@ -62,8 +64,11 @@ public interface Unit {
 	 * @return true if the units are compatible
 	 * @since 2019-01-13
 	 * @since v0.1.0
+	 * @throws NullPointerException
+	 *             if other is null
 	 */
 	default boolean canConvertTo(final Unit other) {
+		Objects.requireNonNull(other, "other must not be null.");
 		return Objects.equals(this.getBase(), other.getBase());
 	}
 
@@ -97,8 +102,11 @@ public interface Unit {
 	 * @throws IllegalArgumentException
 	 *             if {@code other} is incompatible for conversion with this unit (as tested by
 	 *             {@link Unit#canConvertTo}).
+	 * @throws NullPointerException
+	 *             if other is null
 	 */
 	default double convertTo(final Unit other, final double value) {
+		Objects.requireNonNull(other, "other must not be null.");
 		if (this.canConvertTo(other))
 			return other.convertFromBase(this.convertToBase(value));
 		else