I am reading for SCJP and I have a question regarding this line:
Identifiers must start with a letter, a currency character ($), or a connecting character such as the underscore ( _ ). Identifiers cannot start with a number!
It states that a valid identifier name can start with a connecting character such as underscore. I thought underscores were the only valid option? What other connecting characters are there?
Here is a list of connecting characters. These are characters used to connect words.
http://www.fileformat.info/info/unicode/category/Pc/list.htm
U+005F _ LOW LINE
U+203F ‿ UNDERTIE
U+2040 ⁀ CHARACTER TIE
U+2054 ⁔ INVERTED UNDERTIE
U+FE33 ︳ PRESENTATION FORM FOR VERTICAL LOW LINE
U+FE34 ︴ PRESENTATION FORM FOR VERTICAL WAVY LOW LINE
U+FE4D ﹍ DASHED LOW LINE
U+FE4E ﹎ CENTRELINE LOW LINE
U+FE4F ﹏ WAVY LOW LINE
U+FF3F _ FULLWIDTH LOW LINE
This compiles on Java 7.
int _, ‿, ⁀, ⁔, ︳, ︴, ﹍, ﹎, ﹏, _;
An example. In this case tp
is the name of a column and the value for a given row.
Column<Double> ︴tp︴ = table.getColumn("tp", double.class);
double tp = row.getDouble(︴tp︴);
The following
for (int i = Character.MIN_CODE_POINT; i <= Character.MAX_CODE_POINT; i++)
if (Character.isJavaIdentifierStart(i) && !Character.isAlphabetic(i))
System.out.print((char) i + " ");
}
prints
$ _ ¢ £ ¤ ¥ ؋ ৲ ৳ ৻ ૱ ௹ ฿ ៛ ‿ ⁀ ⁔ ₠ ₡ ₢ ₣ ₤ ₥ ₦ ₧ ₨ ₩ ₪ ₫ € ₭ ₮ ₯ ₰ ₱ ₲ ₳ ₴ ₵ ₶ ₷ ₸ ₹ ꠸ ﷼ ︳ ︴ ﹍ ﹎ ﹏ ﹩ $ _ ¢ £ ¥ ₩