long Java Keyword with Examples

Key points about long Java Keyword

  1. The long keyword is used to declare a variable as a long primitive type.
  2. The long primitive type is a signed 64-bit type and is useful for those occasions where an int type is not large enough to hold the desired value.
  3. The Long class is a wrapper class for the long primitive type. It defines MIN_VALUE and MAX_VALUE constants representing the range of values for this type.

long Java Keyword Example

For example, here is a program that computes the number of miles that light will travel in a specified number of days:
// Compute distance light travels using long variables.
class Light {
    public static void main(String args[]) {
        int lightspeed;
        long days;
        long seconds;
        long distance;
        // approximate speed of light in miles per second
        lightspeed = 186000;
        days = 1000; // specify number of days here
        seconds = days * 24 * 60 * 60; // convert to seconds
        distance = lightspeed * seconds; // compute distance
        System.out.print("In " + days);
        System.out.print(" days light will travel about ");
        System.out.println(distance + " miles.");
This program generates the following output:
In 1000 days light will travel about 16070400000000 miles.
Clearly, the result could not have been held in an int variable.