如何从Java的命令行中获取变量？

Question

I've finished writing a java program about a drinksBot. I just have one issue; I need two variables from the command line to be saved as int variables eg.

The user types in:

java DrinksBot 30 40

and the program begins to run, and saves

int cupStock=  30;

int shotStock = 40;  //or whatever the user typed into the command line.

Any help would be greatly appreciated; I'm new to this!

My code begins like this:

  import java.util.Scanner;
  public class DrinksBot {

        static Scanner keyboard = new Scanner (System.in);

           public static void main(String[] args) {

              System.out.print("Hello, what's your name? I have"+cupStock+" cups left, and " + shotStock+" shots left.);

... continues to run rest of program etc.

Answer 1

Read it from args[] array in main method. The variables passed in command line get assigned to String array defined in the main method.

public static void main(String[] args) {
      String cupStock = args[0];
      String shotStock = args[1];
      System.out.print("Hello, what's your name? I have"+cupStock+" cups left, and " + shotStock+" shots left.);
}

run as java DrinksBot 30 40 where the 30 is cupStock and the 40 is shotStock

Update:

to get the value as integer just convert the string to int

int cupStock = Integer.parseInt(args[0]);
int shotStock = Integer.parseInt(args[1]);

Answer 2

Command line arguments are stored in the args array passed to the main method. The first argument is the first element args[0] , the second is args[1] and so on. Since the elements are of type String , you can convert to int using Integer.parseInt(String) :

int cupStock = Integer.parseInt(args[0]);

int shotStock = Integer.parseInt(args[1]);

Of course you should validate the input before doing this by checking the length of the array, otherwise an exception would occur:

if(args.length < 2) {
   // print a message to the user and exit
}