public class Main {
public static void main ( String [ ] argv )
throws Exception {
List stuff = Arrays . asList ( new String [ ] { " a " , " b " } ) ;
List list = new ArrayList ( stuff ) ;
list = Collections . unmodifiableList ( list ) ;
try {
list . set ( 0 , " new value " ) ;
}
catch ( UnsupportedOperationException e ) {
}
Set set = new HashSet ( stuff ) ;
set = Collections . unmodifiableSet ( set ) ;
Map map = new HashMap ( ) ;
map = Collections . unmodifiableMap ( map ) ;
System . out . println ( " 集合现在是只读 " ) ;
}
}