represents a mapping between preference names, which are
case-sensitive strings, and corresponding preference values.
get( ) allows you to query the string value of a
named preference, and
put( ) allows you to set a
string value for a named preference. Although all preference values
are stored as strings, various convenience methods whose names begin
with “get” and
“put” exist to convert preference
values of type
long to and from
remove( ) method allows you to delete a named
preference altogether, and
clear( ) deletes all
preference values stored in a
keys( ) method returns an array of strings
that specify the names of all preferences in the
Preference values are stored in some implementation-dependent
back-end which may be a file, a LDAP directory server, the Windows
Registry, or any other persistant “backing
store”. Note that all the
methods of this class require a default value to be specified. They
return this default if no value has been stored for the named
preference, or if the backing store is unavailable for any reason.
Preferences class is completely independent of
the underlying implementation, except that it enforces an
80-character limit for preference names and
Preference node names (see below), and a
8192-character limit on preference value strings.
Preferences does not have a public construtor. To
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