Develop Reference

Music symbols in unicode on android

We want to draw a music symbols in View.onDraw(),and found that unicode contains a few of symbols.here is the Code Chart
But when i call drawText("\u1D100"),only the four character after u encoded,the last "0" still draw with "0".How to solve this problem.

Strings in Java/Android are encoded using UTF-16. The \u escape notation supports up to 4 hex digits. So, to encode a Unicode codepoint above U+FFFF, you have to encode it as a UTF-16 surrogate pair. This is clearly explained in the Java/Android documentations.
U+1D100 is 0xD834 0xDD00 in UTF-16, so use this instead:
drawText("\uD834\uDD00", ...)
Alternatively, you can convert the Unicode codepoint to a char[] array at runtime and then draw it:
char[] ch = Character.toChars(0x1D100);
drawText(ch, 0, ch.length, ...)
Either way, of course you have to use a font that actually supports U+1D100.

Error using native smiles of Android in text field (Unity3d)

I make application with Unity3d and build it for Android, when I write in input field android native smiles - I got error in line
(invalid utf-16 sequence at 1411555520 (missing surrogate tail)):
r.font.RequestCharactersInTexture(chars, size, style);
chars contains string than contains native android smiles. How I may support native smiles? I use own class for Input Field.

Unfortunately, supporting emojis with Unity is hard. When I implemented this feature, it took about a month to finish it, with a custom text layout engine and string class. So, if this requirement is not particularly important, I would suggest axing this feature.
The reason behind this particular error is that Unity gets characters from the input string one by one, and updates the visual string every character. From the layman point of view, this makes complete sense. However, it doesn't take into account how UTF-16 encoding, which is used in C#, works.
UTF-16 encoding uses 16 bits per a single unicode characters. It is enough for almost all characters that you would normally use. (And, as every developer knows, "almost all" is a red flag that will lay dormant for a long time and then will explode and destroy everything you love.) But it so happens, that Emoji characters are do not fit into 16 bit UTF-16 character, and use a special case — surrogate pair:
Surrogate pair is a pair of UTF-16 characters that represent a single Unicode character. That means that they don't have any meaning on their own individually, and when you try to render a UTF-16 character that is a surrogate head or surrogate tail, you can expect to get an error like this, or something similar.
Essentially, what you need to implement is some kind of buffer, that will accept C# UTF-16 characters one by one, and then pass them to rendering code when it verifies that all surrogate pairs are closed.
Oh, and I almost forgot! Some Emoji characters, like country flags, are represented by two unicode characters. Which means that they can potentially take up to four UTF-16 characters. Aren't text encodings fun?

Apostrophe converting to question mark in textview

I am parsing some external XML into an object and displaying this inside a textview.
Apostrophe's/single quotes are being converted to these silly question mark symbols.
Nothing i've found is working - i've tried using replaceall and escaping it with \', it doesn't give me the desired result.
I've tried setting the textview using:
tv.setText(Html.fromHtml(news_item.getTitle()));
It doesn't seem to work, I can't find any other solutions to this one, your ideas appreciated.

Try this:
tv.setText(news_item.getTitle().replaceAll("\u2019", "'"));
For other Unicode characters, please see this link.

Found it!
The mark you are looking for is called RIGHT SINGLE QUOTATION MARK with a unicode code of U+2019. This particular mark should be replaced via:
String.replace("’", "’");
for proper display.
If that doesn't work, you should do a substitution from that mark to a apostrophe via:
String.replace("’", "'");
or directly:
String.replace("’", "'");
to make sure the display actually displays it.
Close up of the difference between right single quotation mark vs apostrophe: ’ vs '

The documented solution will work, but it is not the right way of fixing this, as the root cause of the problem is encoding. In your case, the source's (XML document) encoding is most likely UTF-8 or some other multi-byte encoding. Your parser or consumer of the data is most likely ISO-8859-1 or ASCII. These characters (right/left apostrophes) are not part of that character set. Therefore, the correct solution is to change the encoding of your parser/processor/consumer to UTF-8.
If this is not the case, then it is probably the opposite. You have a process that writes down characters in UTF-8, but the XML's encoding is not compatible (i.e. ISO-8859-1).
Remember this: ALL characters in ISO-8859-1 are mapped in UTF-8, but not the other way around. So going from ISO-8859-1 to UTF-8 is not a problem. The problem is when you have to make the round trip to ISO-8859-1 to UTF-8. When converting UTF-8 characters, those characters NOT in the ISO character set, will show up funny on your display; either as question marks or "’

More elegant way to decode \u0000 Unicode in an input stream

I'm parsing an input stream coming from Facebook. I'm using something like
BufferedReader in =
new BufferedReader(new InputStreamReader(url.openStream(), "UTF-8"));
And then in.readLine to actually read from the stream.
The stream seems to have Unicode characters already encoded in ASCII, so I see things like \u00e4 (with \u actually being two discrete ASCII characters). Right now, I'm fishing for "\u" and decoding the subsequent two hex bytes, turn them into a char and replace the string with them, which is obviously the worst way to do it.
I'm sure there's a cool way to use a native function to decode the special characters as the stream is being read (I was hoping it could be done on the InputStreamReader layer). But how?

The data format is JSON, which I didn't mention (and which Thanatos already assumed). Using Android's JSON parser will automatically decode the characters properly. Parsing JSON yourself is obviously a dumb idea on several levels.

If you see '\u00e4' with the '\' and the 'u' being separate, then the '0', '0', 'e' and '4' probably make up the 4 hex digits of a 2 byte (16 bit) Unicode character. The notation is based on C99; the alternative is '\U00XXYYZZ' where there are 8 hex digits representing a 32-bit UTF-32 character (but, because Unicode is a 21-bit code set, the first 2 of the 8 digits are always 0, and the next is often (usually) 0 too).
However, that doesn't answer your question about what's the right Android way to read the data, and you are right that there probably is one.

How to remove accent characters from an InputStream

I am trying to parse a Rss2.0 feed on Android using a Pull parser.
XmlPullParser parser = Xml.newPullParser();
parser.setInput(url.open(), null);
The prolog of the feed XML says the encoding is "utf-8". When I open the remote stream and pass this to my Pull Parser, I get invalid token, document not well formed exceptions.
When I save the XML file and open it in the browser(FireFox) the browser reports presence of Unicode 0x12 character(grave accent?) in the file and fails to render the XML.
What is the best way to handle such cases assuming that I do not have any control over the XML being returned?
Thanks.

Where did you find that 0x12 is the grave accent? UTF-8 has the character range 0x00-0x7F encoded the same as ASCII, and ASCII code point 0x12 is a control character, DC2, or CTRL+R.
It sounds like an encoding problem of some sort. The simplest way to resolve that is to look at the file you've saved in a hex editor. There are some things to check:
the byte order mark (BOM) at the beginning might confuse some XML parsers
even though the XML declaration says the encoding is in UTF-8, it may not actually have that encoding, and the file will be decoded incorrectly.
not all unicode characters are legal in XML, which is why firefox refuses to render it. In particular, the XML spec says that that 0x9, 0xA and 0xD are the only valid characters less than 0x20, so 0x12 will definitely cause compliant parsers to grumble.
If you can upload the file to pastebin or similar, I can help find the cause and suggest a resolution.
EDIT: Ok, you can't upload. That's understandable.
The XML you're getting is corrupted somehow, and the ideal course of action is to contact the party responsible for producing it, to see if the problem can be resolved.
One thing to check before doing that though - are you sure you are getting the data undisturbed? Some forms of communication (SMS) allow only 7-bit characters. This would turn 0x92 (ASCII forward tick/apostrophe - grave accent?) into 0x12. Seems like quite a coincidence, particularly if these appear in the file where you would expect an accent.
Otherwise, you will have to try to make best do with what you have:
although not strictly necessary, be defensive and pass "UTF-8" as the second paramter to setInput, on the parser.
similarly, force the parser to use another character encoding by passing a different encoding as the second parameter. Encodings to try in addtion to "UTF-8" are "iso-8859-1" and "UTF-16". A full list of supported encodings for java is given on the Sun site - you could try all of these. (I couldn't find a definitive list of supported encodings for Android.)
As a last resort, you can strip out invalid characters, e.g. remove all characters below 0x20 that are not whitespace (0x9,0xA and 0xD are all whitepsace.) If removing them is difficult, you can replace them instead.
For example
class ReplacingInputStream extends FilterInputStream
{
public int read() throws IOException
{
int read = super.read();
if (read!=-1 && read<0x20 && !(read==0x9 || read==0xA || read==0xB))
read = 0x20;
return read;
}
}
You wrap this around your existing input stream, and it filters out the invalid characters. Note that you could easily do more damage to the XML, or end up with nonsense XML, but equally it may allow you to get out the data you need or to more easily see where the problems lie.

I use to filter it with a regex, but the trick is not trying to get and replace the accents. It depends on the encode and you don't want to change the content.
Try to insert the content of the tags into this tags
Like this
<title>My title</title>
<link>http://mylink.com</link>
<description>My description</description>
To this
<title><![CDATA[My title]]></title>
<link><![CDATA[http://milynk.com]]></link>
<description><![CDATA[My Description]]></description>
The regex shouldn't be very hard to figure out. It works for me, hope it helps for you.

The problem with UTF-8 is that it is a multibyte encoding. As such it needs a way to indicate when a character is formed by more than one byte (maybe two, three, four, ...). The way of doing this is by reserving some byte values to signal multibyte characters. Thus encoding follows some basic rules:
One byte characters have no MSB set (codes compatible with 7-bit ASCII).
Two byte characters are represented by sequence: 110xxxxx 10xxxxxx
Three bytes: 1110xxxx 10xxxxxx 10xxxxxx
Four bytes: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
Your problem is that you may be reading some character string supposedly encoded as UTF-8 (as the XML encoding definition states) but the byte chunk might not be really encoded in UTF-8 (it is a common mistake to declare something as UTF-8 but encoding text with a different encoding such as Cp1252). Your XML parser tries to interpret byte chunks as UTF-8 characters but finds something that does not fit the encoding rules (illegal character). I.e. two bytes with two most significate bytes set would bring an illegal encoding error: 110xxxxx must be always followed by 10xxxxxx (values such as 01xxxxxx 11xxxxxx 00xxxxxx would be illegal).
This problem does not arise when non-variable length encodings are used. I.e. if you state in your XML declaration that your file uses Windows-1252 encoding but you end up using ANSI your only problem will be that non-ASCII characters (values > 127) will render incorrectly.
The solution:
Try to detect encoding by other means.
If you will always be reading data from same source you could sample some files and use an advanced text editor that tries to infer actual encoding of the file (i.e. notepad++, jEdit, etc.).
Do it programatically. Preprocess raw bytes before doing any actual xml processing.
Force actual encoding at the XML processor
Alternatively if you do not mind about non-ASCII characters (no matter if strange symbols appear now and then) you could go directly to step 2 and force XML processing to any ASCII compatible 8-byte fixed length encoding (ANSI, any Windows-XXXX codepage, Mac-Roman encoding, etc.). With your present code you just could try:
XmlPullParser parser = Xml.newPullParser();
parser.setInput(url.open(), "ISO-8859-1");

Calling setInput(istream, null) already means for the pull parser to try to detect the encoding on its own. It obviously fails, due to the fact that there is an actual problem with the file. So it's not like your code is wrong - you can't be expected to be able to parse all incorrect documents, whether ill-formed or with wrong encodings.
If however it's mandatory that you try to parse this particular document, what you can do is modify your parsing code so it's in a function that takes the encoding as a parameter and is wrapped in a try/catch block. The first time through, do not specify an encoding, and if you get an encoding error, relaunch it with ISO-8859-1. If it's mandatory to have it succeed, repeat for other encodings, otherwise call it quits after two.

Before parsing your XML, you may tweak it, and manually remove the accents before you parse it.
Maybe not the best solution so far, but it will do the job.