diff -r 88502b1cf76f -r 7799a51dbe30 test/langtools/tools/javac/patterns/ExamplesFromProposal.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/langtools/tools/javac/patterns/ExamplesFromProposal.java	Wed Nov 27 09:00:01 2019 +0100
@@ -0,0 +1,215 @@
+/*
+ * Copyright (c) 2017, 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8231827
+ * @summary All example code from "Pattern Matching for Java" document, released April 2017, adjusted to current state (no switches, etc)
+ * @compile --enable-preview -source ${jdk.version} ExamplesFromProposal.java
+ * @run main/othervm --enable-preview ExamplesFromProposal
+ */
+
+interface Node {
+}
+
+class IntNode implements Node {
+    int value;
+
+    IntNode(int value) {
+        this.value = value;
+    }
+}
+
+class NegNode implements Node {
+    Node node;
+
+    NegNode(Node node) {
+        this.node = node;
+    }
+}
+
+class MulNode implements Node {
+    Node left, right;
+
+    MulNode(Node left, Node right) {
+        this.left = left;
+        this.right = right;
+    }
+}
+
+class AddNode implements Node {
+    Node left, right;
+
+    AddNode(Node left, Node right) {
+        this.left = left;
+        this.right = right;
+    }
+}
+
+public class ExamplesFromProposal {
+
+    public static Object getSomething() {
+        return new Long(42);
+    }
+
+    public static int eval(Node n) {
+        if (n instanceof IntNode in) return in.value;
+        else if (n instanceof NegNode nn) return -eval(nn.node);
+        else if (n instanceof AddNode an) return eval(an.left) + eval(an.right);
+        else if (n instanceof MulNode mn) return eval(mn.left) * eval(mn.right);
+        else {
+            // should never happen
+            throw new AssertionError("broken");
+        }
+    }
+
+    public static String toString(Node n) {
+        if (n instanceof IntNode in) return String.valueOf(in.value);
+        else if (n instanceof NegNode nn) return "-"+eval(nn.node);
+        else if (n instanceof AddNode an) return eval(an.left) + " + " + eval(an.right);
+        else if (n instanceof MulNode mn) return eval(mn.left) + " * " + eval(mn.right);
+        else {
+            // should never happen
+            throw new AssertionError("broken");
+        }
+    }
+
+    public static Node simplify(Node n) {
+        if (n instanceof IntNode in) {
+            return n;
+        } else if (n instanceof NegNode nn) {
+            return new NegNode(simplify(nn.node));
+        } else if (n instanceof AddNode ad) {
+            n = simplify(ad.left);
+            if (n instanceof IntNode intn) {
+                if (intn.value == 0)
+                    return simplify(ad.right);
+                else
+                    return new AddNode(intn, simplify(ad.right));
+            } else {
+                return new AddNode(simplify(ad.left), simplify(ad.right));
+            }
+        } else if (n instanceof MulNode mn) {
+            return new MulNode(simplify(mn.left), simplify(mn.right));
+        } else {
+            //should never happen
+            throw new AssertionError("broken");
+        }
+    }
+
+    public static void testNode(Node n, int expected) {
+        if (eval(n) != expected)
+            throw new AssertionError("broken");
+    }
+
+    public static void main(String[] args) {
+        Object x = new Integer(42);
+
+        if (x instanceof Integer i) {
+            // can use i here
+            System.out.println(i.intValue());
+        }
+
+        Object obj = getSomething();
+
+        String formatted = "unknown";
+        if (obj instanceof Integer i) {
+            formatted = String.format("int %d", i);
+        }
+        else if (obj instanceof Byte b) {
+            formatted = String.format("byte %d", b);
+        }
+        else if (obj instanceof Long l) {
+            formatted = String.format("long %d", l);
+        }
+        else if (obj instanceof Double d) {
+            formatted = String.format("double %f", d);
+        }
+        else if (obj instanceof String s) {
+            formatted = String.format("String %s", s);
+        }
+        System.out.println(formatted);
+
+        if (obj instanceof Integer i) formatted = String.format("int %d", i);
+        else if (obj instanceof Byte b) formatted = String.format("byte %d", b);
+        else if (obj instanceof Long l) formatted = String.format("long %d", l);
+        else if (obj instanceof Double d) formatted = String.format("double %f", d);
+        else if (obj instanceof String s) formatted = String.format("String %s", s);
+        else formatted = String.format("Something else "+ obj.toString());
+        System.out.println(formatted);
+
+        Node zero = new IntNode(0);
+        Node one = new IntNode(1);
+        Node ft = new IntNode(42);
+
+        Node temp = new AddNode(zero,ft);
+
+        testNode(temp,42);
+
+
+
+        if (toString(simplify(temp)).equals(toString(ft)))
+            System.out.println("Simplify worked!");
+        else
+            throw new AssertionError("broken");
+
+
+        if (toString(simplify(new AddNode(zero,temp))).equals(toString(ft)))
+            System.out.println("Simplify worked!");
+        else
+            throw new AssertionError("broken");
+
+
+        temp = new AddNode(zero,ft);
+        temp = new AddNode(one,temp);
+        temp = new AddNode(zero,temp);
+
+        Node fortythree = new AddNode(one,ft);
+
+        if (toString(simplify(temp)).equals(toString(fortythree)))
+            System.out.println("Simplify worked!");
+        else
+            throw new AssertionError("broken");
+
+
+        x = "Hello";
+
+        if (x instanceof String s1) {
+            System.out.println(s1);
+        }
+        if (x instanceof String s1 && s1.length() > 0) {
+            System.out.println(s1);
+        }
+        if (x instanceof String s1) {
+            System.out.println(s1 + " is a string");
+        } else {
+            System.out.println("not a string");
+        }
+
+        if (!(x instanceof String s1)) {
+            System.out.println("not a string");
+        } else {
+            System.out.println(s1 + " is a string");
+        }
+    }
+}