Disable System.err

Question

Is there a way to set the stream System.err so everything written to it is ignored? (i.e. discarded not outputted)

score 42 · Accepted Answer · answered May 09 '11 at 12:04

42

System.setErr(new PrintStream(new OutputStream() {
    public void write(int b) {
    }
}));

answered May 09 '11 at 12:04

dogbane

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7

I have found another way: System.err.close(); – elou Aug 02 '12 at 14:47
@elou Do you know how to restore the original System.err after you've closed it? – Noumenon Jul 05 '18 at 18:35
2

Hi @Noumenon, I have investigate the question and came to the same conclusion as here: [It is not possible to reopen](https://stackoverflow.com/a/27286893/281188). If you need to reopen, you should prefer to backup the stream with `PrintStream _err = System.err;` before overwriting with `System.setErr(..)`. After that it's possible to restore with `System.setErr(_err)`. Regards, Éric. – elou Jul 10 '18 at 07:43

Peter Lawrey · Answer 2 · 2011-05-09T12:43:07.260

18

You can use System.setErr() to give it a PrintStream which doesn't do anything.

See @dogbane's example for the code.

edited May 09 '11 at 12:43

answered May 09 '11 at 12:01

Peter Lawrey

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score 5 · Answer 3 · answered May 09 '11 at 12:07

Just set Error to dommy implementation:

System.setErr(new PrintStream(new OutputStream() {
            @Override
            public void write(int arg0) throws IOException {
                // keep empty
            }
        }));

You need to have special permission to do that.

RuntimePermission("setIO")

score 1 · Answer 4 · answered May 09 '11 at 12:05

1

You could redirect the err Stream to /dev/null

OutputStream output = new FileOutputStream("/dev/null");
PrintStream nullOut = new PrintStream(output);
System.setErr(nullOut);

answered May 09 '11 at 12:05

cb0

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this is *nix specific, though. – asgs May 09 '11 at 12:05
2

Note: On Windows, use "NUL:" instead of "/dev/null". – dogbane May 09 '11 at 12:06
/dev/null doesn't exist in windows (you can use NUL on those though) – ratchet freak May 09 '11 at 12:09
2

@rachet freak, If you have a directory called `dev` it soon will. ;) (`dev` is short for development on my PC) – Peter Lawrey May 09 '11 at 12:13
FileOutputStream is an overkill for this, you can use common-io NullOutputStream() – Daniel Hári May 22 '23 at 10:45

score 0 · Answer 5 · answered May 22 '23 at 11:44

0

Using commons-io's NullOutputStream, just:

System.setErr(new PrintStream(new NullOutputStream()));

answered May 22 '23 at 11:44

Daniel Hári

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Disable System.err

5 Answers5

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