Using underscore in Numeric Literals in Java

Difficulty Level : Hard
Last Updated : 06 Sep, 2017

From 1.7v onwards we can use ‘_’ under score symbols between digits of numeric literals. You can place underscores only between digits; you cannot place underscores in the following places:

At the beginning or end of a number
Adjacent to a decimal point in a floating point literal
Prior to an F or L suffix
In positions where a string of digits is expected
We can use under score symbols only between the digits if we are using else we will get compile time error.

Valid examples:

Input : int i = 12_34_56; 
Output : 123456

Input : double db = 1_2_3.4_5_6
Output : 123.456

Some invalid examples:

int i = _12345; // Invalid; This
is an identifier, not a numeric literal

double db = 123._456; // Invalid; cannot put 
underscores adjacent to a decimal point

double db 123_.456_; // Invalid; cannot put
underscores at the end of a number

The main advantage of this approach is readability of the code will be improved. At the time of compilation these under score symbols will be removed automatically. We can use more than one under score symbols also between the digits too. For example, following is a valid numeric literal

int x4 = 5_______2;        // OK (decimal literal)

// Java program to illustrate 
// using underscore in Numeric Literals
class UnderScoreSymbols
{
    public static void main(String[] args)
    {
        int i = 12_34_5_6;
        double db = 1_23.45_6;
        int x4 = 5_______2;  
        System.out.println("i = " + i );
        System.out.println("db = " + db );
        System.out.println("x4 = " + x4 );
    }
}

Output:

i = 123456
db = 123.456
x4 = 52

This article is contributed by Shivakant jaiswal. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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