double Java Keyword with Examples

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1. The double keyword is used to create a double primitive type.
2. A double variable may store a double−precision floating point value. Double precision, as denoted by the double keyword, uses 64 bits to store a value. 
3. Double precision is actually faster than single precision on some modern processors that have been optimized for high-speed mathematical calculations.
4. The Double class wraps a value of the primitive type double in an object. An object of type Double contains a single field whose type is double.

The below diagram shows how to create double primitive data type using a double keyword.

double Java Keyword Examples

Here is a short program that uses double variables to compute the area of a circle:

// Compute the area of a circle.
class Area {
    public static void main(String args[]) {
        double pi, r, a;
        r = 10.8; // radius of circle
        pi = 3.1416; // pi, approximately
        a = pi * r * r; // compute area
        System.out.println("Area of circle is " + a);
    }
}

Output:

Area of circle is 366.436224