How to convert Unicode code points to human readable form and print using System.out.println() ?

[Varuna Seneviratna]

How to convert Unicode code points to characters and print using System.out.println(). The emojis at https://home.unicode.org/ cannot be printed. When tried to print, a question mark was the output. Does the encoding of System.out.println() have to be changed?

[Paul Clapham]

Well, unfortunately, yes.

But you can't do that from your Java code. System.out.println writes to the console, which is part of the operating system or runtime environment where you are running it. That may or may not even be possible. So if it's really really important to write emojis to your console, then tell us where you are running your code and somebody might be able to help out. But really I would recommend writing the text to somewhere which supports emojis.

[Varuna Seneviratna]

I just tried out printing Unicode in jshell and, some did work out and some didn't. I wanted to find out how to be able to print any Unicode codepoint to character form or human readable form. This printing was done in the Windows command line.

[Stephan van Hulst]

Note that question marks mean that the user interface is using a font that doesn't have glyphs for the printed characters. Sometimes that means you're printing the wrong characters (on account of using a different encoding for printing the characters than the user interface is using for reading them), but sometimes it also just means that your font just doesn't suffice.

In short, you need to assure two things:

That the Windows command line is using the same encoding that you are using to print characters.

That the Windows command line is using a font that can display the printed characters.

[Campbell Ritchie]

Question too difficult for “beginning” forum: moving.

What happens if you use the SringBuilder.appendCodePoint() method and then print out the StringBuilder object?

[Campbell Ritchie]

Also, what happens if you display the StringBuilder, via its toString() method, on a JOptionPane dialogue?

[Tim Holloway]

You shouldn't have to play games at the codepoint level. Java works with Unicode and only when you set up a print stream with code translation (for example, to ISO-8990-1) will there be a coding issue. I'm pretty sure all major command shells (Windows and Linux) are now defaulting to UTF-8, though, and Java likewise.

On the other hand, your command shell has a specific font assigned to it, and, as Stephan noted, if that font doesn't contain glyph definitions for the Unicode characters you are printing, then the best you'll get is boxes, question-marks, blank spaces or whatever glyph that font has designated for un-renderable character codes.

So it's really a matter of ensuring that your local system preferences are set up compatibly.

Aside from that, emojis on console messages is cute only the first few times. Save them for more light-hearted environments.

[Varuna Seneviratna]

@Tim Holloway,
                 Thanks, Tim.

So it's really a matter of ensuring that your local system preferences are set up compatibly.

In fact, what made me play games at the code point level is to understand how encoding and decoding translation works. How to determine whether the local system preferences are set up compatibly?  And how is it possible to determine whether the issue is a coding issue or that the font doesn't contain glyph definitions for the Unicode characters? By reading a Unicode code point how to determine where the code point lies within Unicode? In UTF-8 or UTF-16?

Java works with Unicode and only when you set up a print stream with code translation (for example, to ISO-8990-1) will there be a coding issue.

I will try to find out answers to these questions and let you know if I succeed.

[Tim Holloway]

"Local system preferences" can be very local indeed. In Linux, at least, I can set a different font for each command shell window if I'm using one of the more flexible terminal apps. Windows I'm less sure of, since some of the stuff I used to reference back when I did Windows seems to have gone into hiding (Microsoft's perennial move-stuff-around-gratuitously game, probably).

An app like MS-WORD of course has its own font selections, including different font selections within individual words.