Eclipse detail formatter string not displaying all Unicode characters

I like to see the clipboard symbol: 📋 (U+1F4CB) in the debugger.

I understand the two codepoints.

Whearat:

I like to detail-format to see it in the debug-tooltip in Unicode.

My current detail-formatter(Preferences->Java-Debug->Detail Formatter) is:

new String(this.getBytes("utf8"), java.nio.charset.Charset.forName("utf8")).concat(" <---")


(the code above does simply nothing than add a <--- to the detail-view)

<---

What formatter do I need to see the character displayed correctly in the yellow tooltip?

import java.nio.charset.Charset;

public class Test {
public static void main(String args) {
byte db = new byte { -16, -97, -109, -117 };
String x = new String(db, Charset.forName("utf8"));
System.out.println(x);
return;
}
}


Looking for an answer drawing from credible and/or official sources.

3 Answers
3

The “📋” character has been defined within the Unicode character set and since String instances are sequences of Unicode characters, they may contain that character. But it lies outside the Basic Multilingual Plane, so software processing it has to handle it with more care. Most notably, it must not try to process it as individual char values, which are UTF-16 units, requiring processing such a character as pair of surrogate characters.

String

char

Your detail formatter specified as

new String(this.getBytes("utf8"), java.nio.charset.Charset.forName("utf8")) …


doesn’t help here, as this.getBytes("utf8") converts the Unicode String instance to a byte array in the UTF-8 encoding, which is then passed to the new String(…, Charset.forName("utf8")) constructor, converting the byte array back to an identical String instance. If Eclipse’s debugger failed to render the original string, it won’t suddenly do it correctly with an identical string after that redundant operation.

this.getBytes("utf8")

String

byte

UTF-8

new String(…, Charset.forName("utf8"))

String

Generally, if Eclipse’s debugger is incapable of correctly rendering strings containing characters outside the Basic Multilingual Plane, there is nothing you can do in a Detail Formatter to fix that, as all processing you will do there, will eventually end up in a String, perhaps after applying a chain of Detail Formatters. So the end result can only be one of two choices, a String with the problematic character removed or a String which Eclipse’s debugger can’t render correctly.

String

String

String

In other words, this is a bug that can only get fixed on Eclipse’s side.

String

String

String

String

0 - uFFFF

uFFFF

Your code and the clipboard emoji 📋 work just fine in IntelliJ 2018.1. Both the debugger's variables view and the console output are working.

It's unlikely this is a problem with the code. Maybe it's the font you are using in your Eclipse that can't print out the UTF emojis? I'd imagine that Eclipse understands the concept of code points when displaying the tooltips.

The code I executed in IntelliJ:

byte db = new byte { -16, -97, -109, -117 };
String x = new String(db, Charset.forName("utf8"));
System.out.println(x);
String f = new String(x.getBytes("utf8"), Charset.forName("utf8")).concat(" <---");
System.out.println(f);


And observed following in the debugger:

You can do this by using the following method:

Go to the eclipse install directory and open your eclipse.ini file and add the following line at the end of your -vmargs arguments in a new line

-vmargs

-Dfile.encoding=UTF-8

-Dfile.encoding=UTF-8

You would have to restart your eclipse after this change

Hope this helps

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