6658779: Regression: HotspotDiagnosticMXBean.getDiagnosticOptions() throws NullPointerException

Add a null check for the VM option string

Reviewed-by: alanb, tbell

jdk/src/share/classes/sun/management/Flag.java

@@ -64,7 +64,8 @@ class Flag {
     }
 
     VMOption getVMOption() {
-        return new VMOption(name, value.toString(), writeable, origin);
+        String val = value == null ? "" : value.toString();
+        return new VMOption(name, val, writeable, origin);
     }
 
     static Flag getFlag(String name) {

jdk/test/com/sun/management/HotSpotDiagnosticMXBean/GetDiagnosticOptions.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2005 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/*
+ * @test
+ * @bug     6658779
+ * @summary Basic Test for HotSpotDiagnosticMXBean.getDiagnosticOptions()
+ * @author  Daniel Fuchs
+ *
+ * @run main GetDiagnosticOptions
+ */
+
+import com.sun.management.HotSpotDiagnosticMXBean;
+import com.sun.management.VMOption;
+import java.lang.management.ManagementFactory;
+import java.util.List;
+import javax.management.MBeanServer;
+
+public class GetDiagnosticOptions {
+    private static String HOTSPOT_DIAGNOSTIC_MXBEAN_NAME =
+        "com.sun.management:type=HotSpotDiagnostic";
+
+    public static void main(String[] args) throws Exception {
+        HotSpotDiagnosticMXBean mbean =
+            sun.management.ManagementFactory.getDiagnosticMXBean();
+        checkDiagnosticOptions(mbean);
+
+        MBeanServer mbs = ManagementFactory.getPlatformMBeanServer();
+        mbean = ManagementFactory.newPlatformMXBeanProxy(mbs,
+                    HOTSPOT_DIAGNOSTIC_MXBEAN_NAME,
+                    HotSpotDiagnosticMXBean.class);
+        checkDiagnosticOptions(mbean);
+    }
+
+    private static void checkDiagnosticOptions(HotSpotDiagnosticMXBean mbean) {
+        List<VMOption> options = mbean.getDiagnosticOptions();
+        for (VMOption opt : options) {
+            System.out.println("option: "+opt.getName()+"="+opt.getValue());
+        }
+    }
+}