Simplify hierarchy units

[lgpl/argeo-commons.git] / org.argeo.util / src / org / argeo / util / LangUtils.java

diff --git a/org.argeo.util/src/org/argeo/util/LangUtils.java b/org.argeo.util/src/org/argeo/util/LangUtils.java
index 36bec240e83601aedd915a342f377b5aef89b1d4..1177d4f5354c53addedc51fddfa10f5d2d71ec25 100644 (file)
--- a/org.argeo.util/src/org/argeo/util/LangUtils.java
+++ b/org.argeo.util/src/org/argeo/util/LangUtils.java
@@ -11,11 +11,12 @@ import java.time.ZonedDateTime;
 import java.time.temporal.ChronoUnit;
 import java.time.temporal.Temporal;
 import java.util.ArrayList;
-import java.util.Collections;
+import java.util.Collection;
 import java.util.Dictionary;
 import java.util.Enumeration;
 import java.util.HashMap;
 import java.util.Hashtable;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
 import java.util.Properties;
@@ -236,6 +237,34 @@ public class LangUtils {
                return values;
        }
 
+       /** Size of an {@link Iterable}, optimised if it is a {@link Collection}. */
+       public static int size(Iterable<?> iterable) {
+               if (iterable instanceof Collection)
+                       return ((Collection<?>) iterable).size();
+
+               int size = 0;
+               for (Iterator<?> it = iterable.iterator(); it.hasNext(); size++)
+                       it.next();
+               return size;
+       }
+
+       public static <T> T getAt(Iterable<T> iterable, int index) {
+               if (iterable instanceof List) {
+                       List<T> lst = ((List<T>) iterable);
+                       if (index >= lst.size())
+                               throw new IllegalArgumentException("Index " + index + " is not available (size is " + lst.size() + ")");
+                       return lst.get(index);
+               }
+               int i = 0;
+               for (Iterator<T> it = iterable.iterator(); it.hasNext(); i++) {
+                       if (i == index)
+                               return it.next();
+                       else
+                               it.next();
+               }
+               throw new IllegalArgumentException("Index " + index + " is not available (size is " + i + ")");
+       }
+
        /*
         * EXCEPTIONS
         */