Longer prefixes are now favoured over shorter prefixes.

Added 'da-' to the unit file, which was previously missing because it
was interpreted as 'deciatto'.  'D-' can still be used.

2 files changed, 39 insertions, 60 deletions

diff --git a/src/org/unitConverter/UnitsDatabase.java b/src/org/unitConverter/UnitsDatabase.java
index 9749e9c..901c6ef 100755
--- a/src/org/unitConverter/UnitsDatabase.java
+++ b/src/org/unitConverter/UnitsDatabase.java
@@ -67,8 +67,8 @@ public final class UnitsDatabase {
 	 * <li>Before attempting to search for prefixes in a unit name, this map will first search for a unit name. So, if
 	 * there are two units, "B" and "AB", and a prefix "A", this map will favour the unit "AB" over the unit "B" with
 	 * the prefix "A", even though they have the same string.</li>
-	 * <li>Shorter prefixes are preferred to longer prefixes. So, if you have units "BC" and "C", and prefixes "AB" and
-	 * "A", inputting "ABC" will return the unit "BC" with the prefix "A", not "C" with the prefix "AB".</li>
+	 * <li>Longer prefixes are preferred to shorter prefixes. So, if you have units "BC" and "C", and prefixes "AB" and
+	 * "A", inputting "ABC" will return the unit "C" with the prefix "AB", not "BC" with the prefix "A".</li>
 	 * </ul>
 	 * </p>
 	 * 
@@ -194,6 +194,7 @@ public final class UnitsDatabase {
 							}
 						}
 
+						// create the unit name
 						final StringBuilder unitNameBuilder = new StringBuilder();
 						for (final int i : this.prefixCoordinates) {
 							unitNameBuilder.append(this.prefixNames.get(i));
@@ -256,32 +257,20 @@ public final class UnitsDatabase {
 
 			@Override
 			public Object[] toArray() {
-				if (this.map.units.isEmpty())
-					// finite, it will work
+				if (this.map.units.isEmpty() || this.map.prefixes.isEmpty())
 					return super.toArray();
-				else {
-					if (this.map.prefixes.isEmpty())
-						// finite, it will work
-						return super.toArray();
-					else
-						// infinite set
-						throw new UnsupportedOperationException("Cannot make an infinite set into an array.");
-				}
+				else
+					// infinite set
+					throw new UnsupportedOperationException("Cannot make an infinite set into an array.");
 			}
 
 			@Override
 			public <T> T[] toArray(final T[] a) {
-				if (this.map.units.isEmpty())
-					// finite, it will work
+				if (this.map.units.isEmpty() || this.map.prefixes.isEmpty())
 					return super.toArray(a);
-				else {
-					if (this.map.prefixes.isEmpty())
-						// finite, it will work
-						return super.toArray(a);
-					else
-						// infinite set
-						throw new UnsupportedOperationException("Cannot make an infinite set into an array.");
-				}
+				else
+					// infinite set
+					throw new UnsupportedOperationException("Cannot make an infinite set into an array.");
 			}
 
 		}
@@ -437,32 +426,21 @@ public final class UnitsDatabase {
 
 			@Override
 			public Object[] toArray() {
-				if (this.map.units.isEmpty())
-					// finite, it will work
+				if (this.map.units.isEmpty() || this.map.prefixes.isEmpty())
 					return super.toArray();
-				else {
-					if (this.map.prefixes.isEmpty())
-						// finite, it will work
-						return super.toArray();
-					else
-						// infinite set
-						throw new UnsupportedOperationException("Cannot make an infinite set into an array.");
-				}
+				else
+					// infinite set
+					throw new UnsupportedOperationException("Cannot make an infinite set into an array.");
+
 			}
 
 			@Override
 			public <T> T[] toArray(final T[] a) {
-				if (this.map.units.isEmpty())
-					// finite, it will work
+				if (this.map.units.isEmpty() || this.map.prefixes.isEmpty())
 					return super.toArray(a);
-				else {
-					if (this.map.prefixes.isEmpty())
-						// finite, it will work
-						return super.toArray(a);
-					else
-						// infinite set
-						throw new UnsupportedOperationException("Cannot make an infinite set into an array.");
-				}
+				else
+					// infinite set
+					throw new UnsupportedOperationException("Cannot make an infinite set into an array.");
 			}
 
 		}
@@ -532,26 +510,26 @@ public final class UnitsDatabase {
 				throw new IllegalArgumentException("Attempted to test for a unit using a non-string name.");
 			final String unitName = (String) key;
 
-			// Then, look for the shortest prefix that is attached to a valid unit
-			String shortestPrefix = null;
-			int shortestLength = Integer.MAX_VALUE;
+			// Then, look for the longest prefix that is attached to a valid unit
+			String longestPrefix = null;
+			int longestLength = 0;
 
 			for (final String prefixName : this.prefixes.keySet()) {
 				// a prefix name is valid if:
 				// - it is prefixed (i.e. the unit name starts with it)
-				// - it is shorter than the existing largest prefix (since I am looking for the smallest valid prefix)
+				// - it is longer than the existing largest prefix (since I am looking for the longest valid prefix)
 				// - the part after the prefix is a valid unit name
 				// - the unit described that name is a linear unit (since only linear units can have prefixes)
-				if (unitName.startsWith(prefixName) && prefixName.length() < shortestLength) {
+				if (unitName.startsWith(prefixName) && prefixName.length() > longestLength) {
 					final String rest = unitName.substring(prefixName.length());
 					if (this.containsKey(rest) && this.get(rest) instanceof LinearUnit) {
-						shortestPrefix = prefixName;
-						shortestLength = prefixName.length();
+						longestPrefix = prefixName;
+						longestLength = prefixName.length();
 					}
 				}
 			}
 
-			return shortestPrefix != null;
+			return longestPrefix != null;
 		}
 
 		@Override
@@ -578,34 +556,34 @@ public final class UnitsDatabase {
 				throw new IllegalArgumentException("Attempted to obtain a unit using a non-string name.");
 			final String unitName = (String) key;
 
-			// Then, look for the shortest prefix that is attached to a valid unit
-			String shortestPrefix = null;
-			int shortestLength = Integer.MAX_VALUE;
+			// Then, look for the longest prefix that is attached to a valid unit
+			String longestPrefix = null;
+			int longestLength = 0;
 
 			for (final String prefixName : this.prefixes.keySet()) {
 				// a prefix name is valid if:
 				// - it is prefixed (i.e. the unit name starts with it)
-				// - it is shorter than the existing largest prefix (since I am looking for the smallest valid prefix)
+				// - it is longer than the existing largest prefix (since I am looking for the longest valid prefix)
 				// - the part after the prefix is a valid unit name
 				// - the unit described that name is a linear unit (since only linear units can have prefixes)
-				if (unitName.startsWith(prefixName) && prefixName.length() < shortestLength) {
+				if (unitName.startsWith(prefixName) && prefixName.length() > longestLength) {
 					final String rest = unitName.substring(prefixName.length());
 					if (this.containsKey(rest) && this.get(rest) instanceof LinearUnit) {
-						shortestPrefix = prefixName;
-						shortestLength = prefixName.length();
+						longestPrefix = prefixName;
+						longestLength = prefixName.length();
 					}
 				}
 			}
 
 			// if none found, returns null
-			if (shortestPrefix == null)
+			if (longestPrefix == null)
 				return null;
 			else {
 				// get necessary data
-				final String rest = unitName.substring(shortestLength);
+				final String rest = unitName.substring(longestLength);
 				// this cast will not fail because I verified that it would work before selecting this prefix
 				final LinearUnit unit = (LinearUnit) this.get(rest);
-				final UnitPrefix prefix = this.prefixes.get(shortestPrefix);
+				final UnitPrefix prefix = this.prefixes.get(longestPrefix);
 
 				return unit.withPrefix(prefix);
 			}
diff --git a/unitsfile.txt b/unitsfile.txt
index 14fb6fb..78f8117 100755
--- a/unitsfile.txt
+++ b/unitsfile.txt
@@ -55,6 +55,7 @@ atto-					1e-18
 zepto-					1e-21
 yocto-					1e-24
 
+da-						deca
 D-						deca
 h-						hecto
 H-						hecto