Adding constant for line.separator and friends

[Joe Darcy]

Martin Buchholz wrote:
> (In response to Joe, who once asked me for little things to add
> to the core libraries)
>
> Lots of classes need to use System.getProperty("line.separator").
> Many don't do it right because you need to use
> a doPrivileged block whenever you read a system property.
> Yet it is no secret - you can divine the line separator
> even if you have no trust with the security manager.
>
> Here's a strawman proposal:
>
> http://cr.openjdk.java.net/~martin/webrevs/openjdk7/line.separator/
>
> diff --git a/src/share/classes/java/lang/System.java
> b/src/share/classes/java/lang/System.java
> --- a/src/share/classes/java/lang/System.java
> +++ b/src/share/classes/java/lang/System.java
> @@ -620,6 +620,32 @@
>      }
>
>      /**
> +     * Defines some standard system properties as constant strings.
> +     */
> +    public static class StandardProperties {
> +        public final static String FILE_SEPARATOR;
> +        public final static String PATH_SEPARATOR;
> +        public final static String LINE_SEPARATOR;
> +
> +        static {
> +            String[] props =
> +                AccessController.doPrivileged
> +                (new PrivilegedAction<String[]>() {
> +                    public String[] run() {
> +                        return new String[] {
> +                            getProperty("file.separator"),
> +                            getProperty("path.separator"),
> +                            getProperty("line.separator")
> +                        };
> +                    }
> +                });
> +            FILE_SEPARATOR = props[0];
> +            PATH_SEPARATOR = props[1];
> +            LINE_SEPARATOR = props[2];
> +        }
> +    }
> +
> +    /**
>       * Sets the system properties to the <code>Properties</code>
>       * argument.
>       * <p>
>   

Hi Martin,

Given that these values are not true constants since they vary across 
platforms, I think it is misleading to make them look like constant by 
having them be "public static final" fields with ALL CAPS names.

I would prefer to see these values returned by wrapper methods that did 
the necessary security checks and caching.

-Joe