Java writing to File or System.out

Question

I need to write characters to a file or to standard output. And I am curious if it could be done with one method.

Now I have something like this:

OutputStream out;    
if(toConsole)
   out = System.out;
else
   out = new FileOutputStream(file);

write(out);
}
void write (OutputStream str){
 ....
 str.write(string);

But it is a problem that I am using (in case when "str" is System.out) write instead print? (print java doc: "string's characters are converted into bytes according to the platform's default character encoding") In case if I would use PrintWriter(or PrintStream) as a parameter then i cannot use BufferedWriter and writing to the file would be slower.

It is possible to use a same code (and same methods) for writing to a file and to System.out? (This is for my school project so I want it to be a "pure" and fully correct)

What you could do is redirect the stdout to your own Printsteeam, as demonstrated [here](http://stackoverflow.com/questions/12945537/how-to-set-output-stream-to-textarea/12945678#12945678), which actually demonstrates a proxy approach, which allows you to redirect the output to somewhere else but also still have it appear in the console. I've used this approach to a capture output of programs that didn't included logging — MadProgrammer, Dec 20 '13 at 21:47
You can easily wrap a PrintWriter/PrintStream/etc around a BufferedWriter as shown in [the doc](http://docs.oracle.com/javase/7/docs/api/java/io/BufferedWriter.html) but personally I wouldn't worry about it either way. — Radiodef, Dec 20 '13 at 21:52

tilpner · Accepted Answer · 2013-12-20T21:55:26.150

What you're trying to accomplish, is to treat the fileoutput and the consoleoutput the same. This is possible, because System.out is a PrintStream, and you can create a PrintStream for a file like this

new PrintStream(yourFile)

or insert a BufferedOutputStream in between

new PrintStream(new BufferedOutputStream(new FileOutputStream(yourFile))).

Note that this is not needed, because PrintStream does buffer its output itself.

I would create a variable (global or not), representing the current output. This might be a PrintStream, either System.out, or a PrintStream around a FileOutputStream, whatever you desire. You would then pass this stream to the write method or call the print methods on it directly.

The advantage is that you can easily switch this without much code modification, you can redirect it wherever you wan't. It's no problem to redirect it to a file and System.out! You wouldn't get that pure flexibility with the way you're writing the method currently.

You could (not saying you should), also redirect System.out directly, using System.setOut. This however is bad style, because it is quite uncommon and might confuse everyone else, if they have not seen the call to System.setOut.

score 0 · Answer 2 · answered Dec 20 '13 at 21:39

System.out is an object of type PrintStream. So yes, you can write to
System.out and/or to another file using exactly the same methods. Just
construct a PrintStream object and direct it to your file. So declare
your out variable as PrintStream to start with.

Java writing to File or System.out

2 Answers2