In Java 7 an underscore characters (_) can be put anywhere between digits in a numeric literals. If application code contains numbers with so many digits, you can use an underscore character to organize digits to the groups of three, four or as much as you want. This absolutly improves code readability.
Examples:
long myPayment = 1_234_567L;
long phoneNumber = 0421_555_1234_5678L;
long niceColor = 0x68_FE_A0;
long someFlags = 0b01101001_10010010;
Rules for this feature
You can place underscore characters only between digits. You cannot place underscores in the following places:- at the beginning or end of a number
- next to a decimal point in a floating point literal
- before an F or L suffix
- in positions where a string of digits is expected
int n = _42; // WARNING! an identifier, not a literal! int n = 42_; // ERROR! underscores at the end of a literal float e = 2_.72; // ERROR! underscore before a decimal point long n = 123_L; // ERROR! underscores at invalid position int a = 0_x0D; // ERROR! underscore in the 0x prefix