Using ProgressBar constructor and building it using ProgressBarBuilder yields different results

[nathanduchesne]

I am experiencing different program behaviour when running this code
ProgressBar pb = new ProgressBar(name, 100);

or this code:

ProgressBar.builder().setTaskName(progressBarName).setInitialMax(progressBarMaxCapacity).setStyle(ProgressBarStyle.ASCII).build();

What I was expecting:
Everything works the same, except case 2 has a different display, since we no longer use Unicode.

What happens:
When using the builder, the default PrintStream is not System.err, but instead is

static ConsoleProgressBarConsumer createConsoleConsumer(int predefinedWidth) {
        PrintStream real = new PrintStream(new FileOutputStream(FileDescriptor.err));
        return createConsoleConsumer(real, predefinedWidth);  // System.err might be overridden by System.setErr
    }

(see Utils.java, line 20-23)

Why this may be a problem:
My code redirects certain streams (typically System.err) to other streams, and hence uses System.setErr() to redirect it. Because of this inconsistency, I can no longer do so.
Additionally, I am uncertain as to what benefits you gain from instantiating the PrintStream the way you do so in the above code, as opposed to using System.err directly.

What can easily be done :)

Would you be open to changing
PrintStream real = new PrintStream(new FileOutputStream(FileDescriptor.err));
with
PrintStream real = System.err;

This would make the whole code consistent. Let me know what you think and if you want me to make a pull request for this change!

Best,
Nathan

[ctongfei]

Thanks Nathan! I think this deliberate choice of instantiating from FileDescriptor.err is to force it to display it on the screen, if stderr is used for something else (which is likely when used within a build system). Maybe we could add a switch somewhere so that the stream can be customized?

[holle]

This (or something very similar) happend to me in a different way:

I was running junit 5 tests from maven and added the ProgressBar due to some tests running in a longer loop.

Initially I simply used:

ProgressBar pb = new ProgressBar("some text", 25000);

This produced fine results.
Then I wanted the ProgresBar to make use of my 270 wide terminal, turns out running as maven "child" the jline-terminal has some trouble detecting the real width. So I started faking things by changing the java code to:

ProgressBar pb = ProgressBar.builder()
                          .setInitialMax(max)
                          .setTaskName(sql)
                          .setMaxRenderedLength(270) // or even 80 or different values
                     //     .setStyle(ProgressBarStyle.COLORFUL_UNICODE_BLOCK)
                     //     .setUnit(StringUtils.EMPTY, 1L)
                     //     .showSpeed(null)
                     //     .hideEta()
                          .build();

This in turn triggered the above behavior of the progress bar rendering a new line each time, even if I limit the rendering length to 80 chars. I grabbed the style, unit etc. from the java ctor in ProgressBar to no avail, with our without those parameters, the rendering is, well "broken".

Running this without maven, i.e. in junit5 standalone mode, the rendering works as expected.

I don not know if this relates to #171 in any way

If I can help, I am glad to test any scenarios or code.

Cheers,
Holger