This program is a very primitive
text formatter,
representative of what people used on most computing platforms before
the rise of standalone graphics-based word processors, laser
printers, and, eventually, desktop publishing, word processors, and
desktop office suites. It simply reads words from a
file -- previously created with a text editor -- and outputs
them until it reaches the right margin, when it calls
println( )
to append a line ending. For example,
here is an input file:
It's a nice day, isn't it, Mr. Mxyzzptllxy? I think we should go for a walk.
Given the above as its input, the Fmt
program will
print the lines formatted neatly:
It's a nice day, isn't it, Mr. Mxyzzptllxy? I think we should go for a walk.
As you can see, it has fitted the text we gave it to the margin and discarded all the line breaks present in the original. Here’s the code:
import java.io.*; import java.util.*; /** * Fmt - format text (like Berkeley Unix fmt). */ public class Fmt { /** The maximum column width */ public static final int COLWIDTH=72; /** The file that we read and format */ BufferedReader in; /** If files present, format each, else format the standard input. */ public static void main(String[] av) throws IOException { if (av.length == 0) new Fmt(System.in).format( ); else for (int i=0; i<av.length; i++) new Fmt(av[i]).format( ); } /** Construct a Formatter given a filename */ public Fmt(String fname) throws IOException { in = new BufferedReader(new FileReader(fname)); } /** Construct a Formatter given an open Stream */ public Fmt(InputStream file) throws IOException { in = new BufferedReader(new InputStreamReader(file)); } /** Format the File contained in a constructed Fmt object */ public void format( ) throws IOException { String w, f; int col = 0; while ((w = in.readLine( )) != null) { if (w.length( ) == 0) { // null line System.out.print(" "); // end current line if (col>0) { System.out.print(" "); // output blank line col = 0; } continue; } // otherwise it's text, so format it. StringTokenizer st = new StringTokenizer(w); while (st.hasMoreTokens( )) { f = st.nextToken( ); if (col + f.length( ) > COLWIDTH) { System.out.print(" "); col = 0; } System.out.print(f + " "); col += f.length( ) + 1; } } if (col>0) System.out.print(" "); in.close( ); } }
A slightly fancier version of this program, Fmt2
,
is in the online source for this book. It uses
"
dot commands” -- lines
beginning with periods -- to give limited
control
over the formatting. A
family of “dot command” formatters includes Unix’s
roff
, nroff, troff
, and
groff
, which are in the same family with
programs called runoff
on Digital Equipment
systems. The original for this is J. Saltzer’s runoff, which
first appeared on Multics and from there made its way into various
OSes. To save trees, I did not include Fmt2
here;
it subclasses Fmt
and overrides the
format( )
method to include
additional
functionality.
3.137.41.205