Java 7 : Using Underscore in Numeric Literals

In Java SE 7 and later, any number of underscore characters (_) can appear anywhere between digits in a numerical literal. It can improve the readability of your code.

   1: public class TEST {

   2:  

   3:     static byte testByte = 0b0011_0101;

   4:     static long testLong = 333_2222_2222L;    

   5:     static int testInt=100_000;

   6:  

   7:     public static void main(String[] args) {

   8:         System.out.println(testByte);

   9:         System.out.println(testLong);        

  10:         System.out.println(testInt);        

  11:     }

  12: }

Allowed

we can place underscores only between digits

Not Allowed

we cannot place underscores in the following places:

• At the beginning or end of a number  (_54 , 54_)
  
• Adjacent to a decimal point in a floating point literal  (1._22)
  
• Prior to an F or L suffix  (2.33_F)
  
• In positions where a string of digits is expected