Java Program to Convert String to Long

A String can be converted into a long in Java using methods provided by the Long wrapper class. This conversion is useful when a numeric value is received as text and needs to be used for arithmetic or other numeric operations.

• Invalid numeric strings cause NumberFormatException.
• The input must be within the valid range of the long data type.

Illustration

Input:"999999999999"
Output:999999999999

Methods to Convert String to Long

1. Long.valueOf()

Converts a String into a Long object representing the numeric value.

Syntax

long varLong = Long.valueOf(str);

public class GFG {

    public static void main(String args[])
    {
        
        // Creating custom string
        String s = "999999999999";

        // Printing the above string
        System.out.println("String - " + s);

        // Converting into Long data type
        long l = Long.valueOf(s);

        // Printing String as Long
        System.out.println("Long - " + l);
    }
}

String - 999999999999
Long - 999999999999

Explanation: Long.valueOf() parses the string and returns a Long object. Java can automatically unbox this object to a primitive long when required. Like parseLong(), it supports a leading - sign and throws NumberFormatException for invalid input.

2. Long.parseLong()

Converts a String into a primitive long value.

Syntax:

long value = Long.parseLong(str);

public class Main {
    public static void main(String[] args) {

        String str = "999999999999";

        long value = Long.parseLong(str);

        System.out.println("String: " + str);
        System.out.println("Long: " + value);
    }
}

String: 999999999999
Long: 999999999999

Explanation: The Long.parseLong(str) method converts the numeric String "999999999999" into a primitive long value. The converted value is then stored in the value variable and printed.