Name: skT88420 Date: 05/25/99


The following is a proposal for a new class called "java.io.Encoding".
If implemented as I've outlined, it would provide the following
benefits to the Java platform:

1 - The ability to determine which encodings are supported by the
current platform.
2 - The ability to determine the default native encoding (this is
currently logged as RFE 4175635)
3 - The ability to determine if a given encoding is reversible
(this is logged as RFE 4216686)

// java/io/Encoding.java

package java.io;

/**
 * Provides information about file encodings supported by the
 * system. It is not possible to sub-class this class, nor is
 * it possible to create new instances except via the
 * getEncoding method.
 */

public class Encoding {

    // Add constants for common encodings which are guaranteed
    // to be available on ALL platforms...

    public static final Encoding ISO8859_1;
    public static final Encoding UTF8;
    public static final Encoding UTF16;
    // more...

    /** Hidden constructor */
    private Encoding();

    /**
     * Returns a list of the supported encodings on this platform
     */
    public static Encoding[] getSupportedEncodings();

    /**
     * Returns the default encoding for the platform
     */
    public static Encoding getDefaultEncoding();

    /**
     * Changes the default encoding. This may or may not be a
     * good thing to have
     */
    public static void setDefaultEncoding(Encoding newDefault);

    /**
     * Returns a shared instance of the Encoding object for
     * the given encoding.
     */
    public static Encoding getEncoding(String name) throws UnsupportedEncodingException;

    /**
     * Returns the encoding's name ie "8859_1" or "UTF8"
     */
    public String getName();

    /**
     * Returns a short description of the encoding. This should
     * probably be localized. ie "Windows Latin 1"
     */
    public String getDescription();

    /**
     * As above but using the given locale
     */
    public String getDescription(java.util.Locale locale);

    /**
     * Returns true if there is a one-to-one correspondence of
     * bytes to characters. See RFE 4216686
     */
    public boolean isReversible();

    /**
     * Returns getName()
     */
    public String toString();
}

In addition, any constructors which currently take an encoding
name as a string should be overridden with versions that take
an Encoding object. I suggest deprecating the old constructors
in favor of using Encoding objects.
(Review ID: 83464)
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