Added unit prefixes and made SI reuse base units.

1 files changed, 8 insertions, 1 deletions

diff --git a/src/unitConverter/unit/UnitSystem.java b/src/unitConverter/unit/UnitSystem.java
index 0a50062..d641832 100755
--- a/src/unitConverter/unit/UnitSystem.java
+++ b/src/unitConverter/unit/UnitSystem.java
@@ -16,6 +16,8 @@
  */
 package unitConverter.unit;
 
+import java.util.Objects;
+
 import unitConverter.dimension.UnitDimension;
 
 /**
@@ -31,9 +33,14 @@ public interface UnitSystem {
 	 * @param dimension
 	 *            dimension used by base unit
 	 * @return base unit
+	 * @throws NullPointerException
+	 *             if dimension is null
 	 * @since 2019-01-25
 	 */
-	BaseUnit getBaseUnit(UnitDimension dimension);
+	default BaseUnit getBaseUnit(final UnitDimension dimension) {
+		Objects.requireNonNull(dimension, "dimension must not be null.");
+		return new BaseUnit(dimension, this);
+	}
 
 	/**
 	 * @return name of system