diff --git a/tools/droiddoc/src/Hierarchy.java b/tools/droiddoc/src/Hierarchy.java
new file mode 100755
index 0000000..ac5e1dc
--- /dev/null
+++ b/tools/droiddoc/src/Hierarchy.java
@@ -0,0 +1,155 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.util.HashMap;
+import java.util.TreeSet;
+import java.util.Set;
+import org.clearsilver.HDF;
+
+public class Hierarchy
+{
+    public static void makeHierarchy(HDF hdf, ClassInfo[] classes)
+    {
+        HashMap<String,TreeSet<String>> nodes
+                                    = new HashMap<String,TreeSet<String>>();
+
+        for (ClassInfo cl: classes) {
+            String name = cl.qualifiedName();
+
+            TreeSet<String> me = nodes.get(name);
+            if (me == null) {
+                me = new TreeSet<String>();
+                nodes.put(name, me);
+            }
+
+            ClassInfo superclass = cl.superclass();
+            String sname = superclass != null
+                                    ? superclass.qualifiedName() : null;
+            if (sname != null) {
+                TreeSet<String> s = nodes.get(sname);
+                if (s == null) {
+                    s = new TreeSet<String>();
+                    nodes.put(sname, s);
+                }
+                s.add(name);
+            }
+        }
+
+        /*
+        Set<String> keys = nodes.keySet();
+        for (String n: keys) {
+            System.out.println("class: " + n);
+
+            TreeSet<String> values = nodes.get(n);
+            for (String v: values) {
+                System.out.println("       - " + v);
+            }
+        }
+        */
+
+        int depth = depth(nodes, "java.lang.Object");
+
+        hdf.setValue("classes.0", "");
+        hdf.setValue("colspan", "" + depth);
+
+        recurse(nodes, "java.lang.Object", hdf.getObj("classes.0"),depth,depth);
+
+        if (false) {
+            Set<String> keys = nodes.keySet();
+            if (keys.size() > 0) {
+                System.err.println("The following classes are hidden but"
+                        + " are superclasses of not-hidden classes");
+                for (String n: keys) {
+                    System.err.println("  " + n);
+                }
+            }
+        }
+    }
+
+    private static int depth(HashMap<String,TreeSet<String>> nodes,
+                                String name)
+    {
+        int d = 0;
+        TreeSet<String> derived = nodes.get(name);
+        if (derived != null && derived.size() > 0) {
+            for (String s: derived) {
+                int n = depth(nodes, s);
+                if (n > d) {
+                    d = n;
+                }
+            }
+        }
+        return d + 1;
+    }
+
+    private static boolean exists(ClassInfo cl)
+    {
+        return cl != null && !cl.isHidden() && cl.isIncluded();
+    }
+
+    private static void recurse(HashMap<String,TreeSet<String>> nodes,
+                                String name, HDF hdf, 
+                                int totalDepth, int remainingDepth)
+    {
+        int i;
+
+        hdf.setValue("indent", "" + (totalDepth-remainingDepth-1));
+        hdf.setValue("colspan", "" + remainingDepth);
+
+        ClassInfo cl = Converter.obtainClass(name);
+
+        hdf.setValue("class.label", cl.name());
+        hdf.setValue("class.qualified", cl.qualifiedName());
+        if (cl.checkLevel()) {
+            hdf.setValue("class.link", cl.htmlPage());
+        }
+
+        if (exists(cl)) {
+            hdf.setValue("exists", "1");
+        }
+
+        i = 0;
+        for (ClassInfo iface: cl.interfaces()) {
+            hdf.setValue("interfaces." + i + ".class.label", iface.name());
+            hdf.setValue("interfaces." + i + ".class.qualified", iface.qualifiedName());
+            if (iface.checkLevel()) {
+                hdf.setValue("interfaces." + i + ".class.link", iface.htmlPage());
+            }
+            if (exists(cl)) {
+                hdf.setValue("interfaces." + i + ".exists", "1");
+            }
+            i++;
+        }
+
+        TreeSet<String> derived = nodes.get(name);
+        if (derived != null && derived.size() > 0) {
+            hdf.setValue("derived", "");
+            HDF children = hdf.getObj("derived");
+            i = 0;
+            remainingDepth--;
+            for (String s: derived) {
+                String index = "" + i;
+                children.setValue(index, "");
+                recurse(nodes, s, children.getObj(index), totalDepth,
+                        remainingDepth);
+                i++;
+            }
+        }
+
+        nodes.remove(name);
+    }
+}
+