The Spec for File.setExecutable(boolean executable) and File.setExecutable(boolean executable,boolean ownerOnly) says
"Parameters:
    executable - If true, sets the access permission to allow execute operations; if false to disallow read operations"

   But if executable is false, it does not disallow read operations as mentioned in the spec.
please see the following version,code and Result.

<version>
bash-3.00$ java -version
java version "1.6.0-rc"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-rc-b65)
Java HotSpot(TM) Client VM (build 1.6.0-rc-b65, mixed mode)
</version>

<code>
import java.io.File;
  class setExecute {
    public static void main(String ... s){
       File file = new File("hello.sh");
       if (file.exists()) {
         System.out.println("Can Execute " + file.canExecute());
         System.out.println("setExecute(false) "+file.setExecutable(false));
         System.out.println("Can Execute " + file.canExecute());
         System.out.println("Can Read " + file.canRead());
       }
    }
}
</code>
<Result>
Permissions for the file 'hello.sh'
bash-3.00$ ls -al hello.sh
-rwxrw-rw- 1 rg157576 staff 22 Dec 27 11:51 hello.sh

bash-3.00$ java setExecute
Can Execute true
setExecute(false) true
Can Execute false
Can Read true
</Result>
  It seems to be spec bug which should say
"Parameters:
    executable - If true, sets the access permission to allow execute operations; if false to disallow execute operations"
(1) The javadoc for File.canExecute() says
        Throws:
             SecurityException - If a security manager exists and its
             SecurityManager.checkExec(java.lang.String) method denies read access to the file
   
     -- It should say SecurityManager.checkExec(java.lang.String) method denies execute access to the file (or) method denies creation of subprocess.

   (2) @since tag is missing for File.canExecute().