Illegal Character when trying to compile java code

Question

I have a program that allows a user to type java code into a rich text box and then compile it using the java compiler. Whenever I try to compile the code that I have writte

Answer 1

The BOM is generated by, say, File.WriteAllText() or StreamWriter when you don't specify an Encoding. The default is to use the UTF8 encoding and generate a BOM. You can tell the java compiler about this with its -encoding command line option.

The path of least resistance is to avoid generating the BOM. Do so by specifying System.Text.Encoding.Default, that will write the file with the characters in the default code page of your operating system and doesn't write a BOM. Use the File.WriteAllText(String, String, Encoding) overload or the StreamWriter(String, Boolean, Encoding) constructor.

Just make sure that the file you create doesn't get compiled by a machine in another corner of the world. It will produce mojibake.

Answer 2

That's a problem related to BOM (Byte Order Mark) character. Byte Order Mark BOM is an Unicode character used for defining a text file byte order and comes in the start of the file. Eclipse doesn't allow this character at the start of your file, so you must delete it. for this purpose, use a rich text editor like Notepad++ and save the file with encoding "UTF-8 without BOM". That should remove the problem.

I have copy pasted the some content from a website to a Notepad++ editor,
it shows the "LS" with black background. Have deleted the "LS" content and 
have copy the same content from notepad++ to java file, it works fine.

Answer 3

Even I was facing this issue as am using notepad++ to code. It is very convenient to type the code in notepad++. However after compiling I get an error " error: illegal character: '\u00bb'". Solution : Start writing the code in older version of notepad(which will be there by default in your PC) and save it. Later the modifications can be done using notepad++. It works!!!

Answer 4

http://en.wikipedia.org/wiki/Byte_order_mark

The byte order mark (BOM) is a Unicode character used to signal the endianness (byte order) of a text file or stream. Its code point is U+FEFF. BOM use is optional, and, if used, should appear at the start of the text stream. Beyond its specific use as a byte-order indicator, the BOM character may also indicate which of the several Unicode representations the text is encoded in.

The BOM is a funky-looking character that you sometimes find at the start of unicode streams, giving a clue what the encoding is. It's usually handles invisibly by the string-handling stuff in Java, so you must have confused it somehow, but without seeing your code, it's hard to see where.

You might be able to fix it trivially by manually stripping the BOM from the string before feeding it to javac. It probably qualifies as whitespace, so try calling trim() on the input String, and feeding the output of that to javac.

Answer 5

1. If using an IDE, specify the java file encoding (via the properties panel)
2. If NOT using an IDE, use an advanced text-editor (I can recommend Notepad++) and set the encoding to "UTF without BOM", or "ANSI", if that suits you.

Answer 6

That's a byte order mark, as everyone says.

javac does not understand the BOM, not even when you try something like

javac -encoding UTF8 Test.java

You need to strip the BOM or convert your source file to another encoding. Notepad++ can convert a single files encoding, I'm not aware of a batch utility on the Windows platform for this.

The java compiler will assume the file is in your platform default encoding, so if you use this, you don't have to specify the encoding.