You could assign value of n
as 0
or any other value by default and use if(args.length > 0) {
to check whether any arguments is given. Below is full example with comments:
public class Infinity { public static void main(String args[]) { /* Start by assigning your default value to n, here it is 0 If valid argument is not given, your program runs starting from this value */ int n = 0; // If any arguments given, we try to parse it if(args.length > 0) { try { n = Integer.parseInt(args[0]); } catch (NumberFormatException e) { System.err.println("Argument" + args[0] + " must be an integer."); // Program ends System.exit(1); } } // All good, n is either default (0) or user entered value while(true) { System.out.println(n); n++; } } }
Note: Users which are not so familiar with java, this program can be run by:
- Saving it to
Infinity.java
- Compiling it with cmd or terminal by writing:
javac Infinity.java
- Executing it with:
java Infinity
orjava Infinity 1000
(or any other value)
Cheers.