Added compact().

git-svn-id: https://samskivert.googlecode.com/svn/trunk@649 6335cc39-0255-0410-8fd6-9bcaacd3b74c

projects/samskivert/src/java/com/samskivert/util/IntListUtil.java

@@ -1,5 +1,5 @@
 //
-// $Id: IntListUtil.java,v 1.1 2001/11/06 02:13:29 mdb Exp $
+// $Id: IntListUtil.java,v 1.2 2002/03/14 03:48:44 mdb Exp $
 
 package com.samskivert.util;
 
@@ -261,6 +261,32 @@ public class IntListUtil
         return val;
     }
 
+    /**
+     * Converts a sparse array (with zero-valued entries) into a compact
+     * array (where all elements contain non-zero values) with ordering
+     * preserved.
+     */
+    public static int[] compact (int[] list)
+    {
+        int llength = list.length, lcount = 0;
+        // count up the non-zero entries
+        for (int i = 0; i < llength; i++) {
+            if (list[i] != 0) {
+                lcount++;
+            }
+        }
+
+        int[] nlist = new int[lcount];
+        int n = 0;
+        for (int i = 0; i < llength; i++) {
+            if (list[i] != 0) {
+                nlist[n++] = list[i];
+            }
+        }
+
+        return nlist;
+    }
+
     /**
      * Creates a new list that will accomodate the specified index and
      * copies the contents of the old list to the first.