--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/samples/getclassnpe.js	Fri Feb 06 19:28:26 2015 +0530
@@ -0,0 +1,122 @@
+#// Usage: jjs getclassnpe.js -- <directory>
+
+/*
+ * Copyright (c) 2015, 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.
+ */
+
+/*
+ * java.lang.Object.getClass() is sometimes used to do null check. This
+ * obfuscating Object.getClass() check relies on non-related intrinsic
+ * performance, which is potentially not available everywhere.
+ * See also http://cr.openjdk.java.net/~shade/scratch/NullChecks.java
+ * This nashorn script checks for such uses in your .java files in the
+ * given directory (recursively).
+ */
+
+if (arguments.length == 0) {
+    print("Usage: jjs getclassnpe.js -- <directory>");
+    exit(1);
+}
+
+// Java types used
+var File = Java.type("java.io.File");
+var Files = Java.type("java.nio.file.Files");
+var StringArray = Java.type("java.lang.String[]");
+var ToolProvider = Java.type("javax.tools.ToolProvider");
+var MethodInvocationTree = Java.type("com.sun.source.tree.MethodInvocationTree");
+var TreeScanner = Java.type("com.sun.source.util.TreeScanner");
+
+// parse a specific .java file to check if it uses
+// Object.getClass() for null check.
+function checkGetClassNPE() {
+    // get the system compiler tool
+    var compiler = ToolProvider.systemJavaCompiler;
+    // get standard file manager
+    var fileMgr = compiler.getStandardFileManager(null, null, null);
+    // Using Java.to convert script array (arguments) to a Java String[]
+    var compUnits = fileMgr.getJavaFileObjects(
+        Java.to(arguments, StringArray));
+    // create a new compilation task
+    var task = compiler.getTask(null, fileMgr, null, null, null, compUnits);
+    // subclass SimpleTreeVisitor - to check for obj.getClass(); statements
+    var GetClassNPEChecker = Java.extend(TreeScanner);
+
+    var visitor = new GetClassNPEChecker() {
+        lineMap: null,
+        sourceFile: null,
+
+        // save compilation unit details for reporting
+        visitCompilationUnit: function(node, p) {
+           this.sourceFile = node.sourceFile;
+           this.lineMap = node.lineMap;
+           return Java.super(visitor).visitCompilationUnit(node, p);
+        },
+
+        // look for "foo.getClass();" expression statements
+        visitExpressionStatement: function(node, p) {
+            var expr = node.expression;
+            if (expr instanceof MethodInvocationTree) {
+                var name = String(expr.methodSelect.identifier);
+
+                // will match any "getClass" call with zero arguments!
+                if (name == "getClass" && expr.arguments.size() == 0) {
+                    print(this.sourceFile.getName()
+                     + " @ "
+                     + this.lineMap.getLineNumber(node.pos)
+                     + ":"
+                     + this.lineMap.getColumnNumber(node.pos));
+
+                    print("\t", node);
+                }
+            }
+        }
+    }
+
+    for each (var cu in task.parse()) {
+        cu.accept(visitor, null);
+    }
+}
+
+// for each ".java" file in the directory (recursively)
+function main(dir) {
+    Files.walk(dir.toPath()).
+      forEach(function(p) {
+          var name = p.toFile().absolutePath;
+          if (name.endsWith(".java")) {
+              try {
+                  checkGetClassNPE(p.toFile().getAbsolutePath());
+              } catch (e) {
+                  print(e);
+              }
+          }
+      });
+}
+
+main(new File(arguments[0]));