The double keyword is a data type which is used to store decimal point values ranging from 1.7e-308 to 1.7e+308. This range is represented in “scientific notation”, in normal form you can consider 1.7e+308 equivalent to 17 followed by 307 zeroes.
public class JavaExample {
public static void main(String[] args) {
double num = 2005.455d; //a double variable
System.out.println(num); //prints the value of num
}
}
Output:
2005.455
You can argue that a float data type servers the same purpose as it can store floating point values then why we need double data type? A double data type has larger range than a float data type so it can be used for extremely large and extremely small numbers.
Example of double keyword with scientific notation
In the beginning, we used scientific notation to represent the range of double data type. Let’s take an example to understand this notation.
public class JavaExample {
public static void main(String[] args) {
double num = 101e+4; //equal to 101*10^4
double num2 = 50e-4; //equal to 50*10^-4
System.out.println(num);
System.out.println(num2);
}
}
Output:
1010000.0 0.005