java.io.FileReader/Writer: Want to change encoding converter

The character encoding converter can't be changed on FileReader and FileWriter
classes. On the system there are some files which are described with the
character encoding other than system default.

For example, files which are described with JIS, Shift-JIS and EUC-JIS character
encoding coexit on Japanese Solaris. But present FileReader and FileWriter only
read from and write into file with system default character encoding.

The constracters which the character encoding converter is specified with
need to be added like InputStreamReader and OutputStreamWriter classes on
FileReader and FileWriter classes