--- /dev/null	2014-02-02 21:38:47.000000000 +0800
+++ new/src/share/sample/stream/Subset.java	2014-02-02 21:38:47.000000000 +0800
@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2013 Oracle and/or its affiliates. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *   - Redistributions of source code must retain the above copyright
+ *     notice, this list of conditions and the following disclaimer.
+ *
+ *   - Redistributions in binary form must reproduce the above copyright
+ *     notice, this list of conditions and the following disclaimer in the
+ *     documentation and/or other materials provided with the distribution.
+ *
+ *   - Neither the name of Oracle nor the names of its
+ *     contributors may be used to endorse or promote products derived
+ *     from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+ * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * This source code is provided to illustrate the usage of a given feature
+ * or technique and has been deliberately simplified. Additional steps
+ * required for a production-quality application, such as security checks,
+ * input validation and proper error handling, might not be present in
+ * this sample code.
+ */
+package stream;
+
+import stream.data.Customer;
+import stream.data.Order;
+import java.util.Comparator;
+import java.util.List;
+import java.util.stream.Collectors;
+
+/**
+ * A demo shows how does Stream's subset works. This demo provides two methods
+ * which is using substream method on Stream to get subset of the elements. Note
+ * we can use substream on sorted stream to get top number elements, but we
+ * can't guarantee the element order if stream is not sorted.
+ *
+ * @author hyan
+ */
+public class Subset extends DemoHelper {
+
+    /**
+     * Returns a List that contains numbers order which customer is from state,
+     * also execute action on every returned order element. The number must be a
+     * non-negative digit.
+     * <p>
+     *
+     * @param number integer how many orders are expected to be returned
+     * @param state state that customer of order belong to
+     * @return a list contains top number customers that sorted by comp
+     */
+    public static List<Order> firstNOrdersFromState(int number,
+            String state) {
+        return customers.stream().
+                //only take customers from a particular state
+                filter(c -> state.equals(c.getRegion())).
+                //get orders of those customers
+                flatMap(c -> c.getOrders().stream()).
+                //get first number of orders
+                limit(number).
+                //collect to a list
+                collect(Collectors.toList());
+    }
+
+    /**
+     * Returns a List that contains numbers customer sorted by comp, also
+     * execute action on every returned customer element. The number must be a
+     * non-negative digit.
+     * <p>
+     *
+     * @param number integer how many customers are expected to be returned
+     * @param comp Comparator to compare customer
+     * @return a list contains top number customers that sorted by comp
+     */
+    public static List<Customer> topNCustomer(int number,
+            Comparator<Customer> comp) {
+        //We keep result in topN, then we can test it
+        return customers.stream()
+.                //sort customers by comp
+                sorted(comp).
+                //get first number of orders
+                limit(number).
+                //collect to a list
+                collect(Collectors.toList());
+    }
+}