Java 7 - Underscores in Numeric Literals

In this tutorial we will discuss about Underscore in Numberic feature added in Java 7. This is a nice and small feature which has added in Java 7 gives good readability for our codes. Its nothing but we can use underscores ( _ ) in-between numberic values in our code. Underscore can be added anywhere in the value part with few constraints listed below,

ALLOWED:
In-between 2 numbers or hexadecimal values or binary values are allowed. Below are the few valied literals by using underscore which are given in Oracle docs.

long creditCardNumber = 1234_5678_9012_3456L;
long socialSecurityNumber = 999_99_9999L;
float pi = 3.14_15F;
long hexBytes = 0xFF_EC_DE_5E;
long hexWords = 0xCAFE_BABE;
long maxLong = 0x7fff_ffff_ffff_ffffL;
byte nybbles = 0b0010_0101;
long bytes = 0b11010010_01101001_10010100_10010010;

NOT ALLOWED:

Can't place underscore at beginning or end of the numberic value.
Adjacent to a decimal point in a floating point value literal is not allowed
Prior to an F or L suffix are not allowed
Positions where a string of digits is expected are not allowed
 
float pi1 = 3_.1415F; // Invalid; cannot put underscores adjacent to a decimal point
float pi2 = 3._1415F; // Invalid; cannot put underscores adjacent to a decimal point
long socialSecurityNumber1 = 999_99_9999_L;         // Invalid; cannot put underscores prior to an L suffix

int x1 = _52;            // This is an identifier, not a numeric literal
int x2 = 5_2;            // OK (decimal literal)
int x3 = 52_;            // Invalid; cannot put underscores at the end of a literal
int x4 = 5_______2;  // OK (decimal literal)

int x5 = 0_x52;        // Invalid; cannot put underscores in the 0x radix prefix
int x6 = 0x_52;        // Invalid; cannot put underscores at the beginning of a number
int x7 = 0x5_2;        // OK (hexadecimal literal)
int x8 = 0x52_;        // Invalid; cannot put underscores at the end of a number

int x9 = 0_52;         // OK (octal literal)
int x10 = 05_2;       // OK (octal literal)
int x11 = 052_;       // Invalid; cannot put underscores at the end of a number
 
Lets see one small example by using underscore in numeric literals.
 

public class LiteralsExample {
   public static void main(String[] arg){
       
       float x1 = 52.4_5F;              
       float x2 = 5_2.12F;            
       
       int x3 = 52_3;              
       int x4 = 5_______2;        
       
       System.out.println("FLOAT VALUE :"+(x1+x2));
       System.out.println("INT VALUE   :"+(x3+x4));    
   }
}

OUTPUT:

FLOAT VALUE :104.57
INT VALUE   :575