--- a/langtools/src/share/classes/com/sun/tools/javap/JavapTask.java	Wed Sep 05 12:00:30 2012 -0700
+++ b/langtools/src/share/classes/com/sun/tools/javap/JavapTask.java	Fri Sep 07 11:12:16 2012 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2009, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2012, 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
@@ -374,8 +374,8 @@
         task_locale = locale;
     }
 
-    public void setLog(PrintWriter log) {
-        this.log = log;
+    public void setLog(Writer log) {
+        this.log = getPrintWriterForWriter(log);
     }
 
     public void setLog(OutputStream s) {
@@ -383,7 +383,7 @@
     }
 
     private static PrintWriter getPrintWriterForStream(OutputStream s) {
-        return new PrintWriter(s, true);
+        return new PrintWriter(s == null ? System.err : s, true);
     }
 
     private static PrintWriter getPrintWriterForWriter(Writer w) {

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/langtools/test/tools/javap/T7186925.java	Fri Sep 07 11:12:16 2012 -0700
@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2012, 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 7186925
+ * @summary JavapTask passes null to java.io.Writer
+ */
+
+import java.io.*;
+import java.util.*;
+import javax.tools.*;
+import com.sun.tools.javap.*;
+
+public class T7186925
+{
+    public static void main(String... args) {
+        new T7186925().run();
+    }
+
+    void run() {
+        verify("java.lang.Object");
+        if (errors > 0)
+            throw new Error(errors + " found.");
+    }
+
+    void verify(String className) {
+        try {
+            JavaFileManager fileManager = JavapFileManager.create(null, null);
+            JavaFileObject fo = fileManager.getJavaFileForInput(StandardLocation.PLATFORM_CLASS_PATH, className, JavaFileObject.Kind.CLASS);
+            if (fo == null) {
+                error("Can't find " + className);
+            } else {
+                JavapTask t = new JavapTask(null, fileManager, null);
+                t.handleOptions(new String[] { "-sysinfo", className });
+                JavapTask.ClassFileInfo cfInfo = t.read(fo);
+                expectEqual(cfInfo.cf.byteLength(), cfInfo.size);
+            }
+        } catch (NullPointerException ee) {
+            ee.printStackTrace();
+            error("Exception: " + ee);
+        } catch (Exception ee) {
+            System.err.println("Caught exception: " + ee);
+        }
+    }
+
+    void expectEqual(int found, int expected) {
+        if (found != expected)
+            error("bad value found: " + found + " expected: " + expected);
+    }
+
+    void error(String msg) {
+        System.err.println(msg);
+        errors++;
+    }
+
+    int errors;
+}