Java Double parseDouble() example

In this guide, you will learn about the Double parseDouble() method in Java programming and how to use it with an example.

1. Double parseDouble() Method Overview

Definition:

The parseDouble() method of the Java Double class converts a string representation of a floating-point number to its double primitive type.

Syntax:

double Double.parseDouble(String s)

Parameters:

String s: The string to be parsed.

Key Points:

- If the string does not contain a parsable double, a NumberFormatException will be thrown.

- This method can handle string representations of both regular floating-point numbers and numbers in scientific notation.

- Leading and trailing whitespaces in the string are allowed and will be ignored during the parsing.

- The method is static, so it's invoked on the class (Double) and not on an instance of the class.

2. Double parseDouble() Method Example

public class ParseDoubleExample {
    public static void main(String[] args) {
        // Parse a regular floating-point number
        String numberStr = "123.45";
        double value = Double.parseDouble(numberStr);
        System.out.println("Parsed double from string: " + value);

        // Parse a number in scientific notation
        String sciNotationStr = "1.23e2"; // Represents 1.23 * 10^2
        double sciValue = Double.parseDouble(sciNotationStr);
        System.out.println("Parsed double from scientific notation: " + sciValue);
    }
}

Output:

Parsed double from string: 123.45
Parsed double from scientific notation: 123.0

Explanation:

In the provided example, we first parsed a regular floating-point number "123.45" from a string using the parseDouble() method. 

We then demonstrated the method's capability to handle scientific notation by parsing the string "1.23e2", which represents the value \(1.23 \times 10^2\), resulting in a double value of 123.0.