A basic program that gets input x (Integer) and limit (Integer) from the user and prints the multiplication list of Integer x from 1 to limit. By this program, you can understand the usage of commandline arguments, use of arithmetic operators, printing variables and user-defined method.

Task: Print a multiplication table of number x from 1 to limit

  Eg: x = 2, limit = 3
  Output: 
          2 x 1 = 2
          2 x 2 = 4
          2 x 3 = 6

The filename must have the same name as the public class name, This is to ensure that the Java Virtual Machine (JVM) understands the entry point of the program

To run the program, open your commandline and type the following:

• Without Commandline Arguments

 $ ..\JavaBasic> javac .\MultiplicationTable\MultiplicationTable.java
 $ ..\JavaBasic> java MultiplicationTable.MultiplicationTable

• With Commandline Arguments

 $ ..\JavaBasic> javac .\MultiplicationTable\MultiplicationTable.java
 $ ..\JavaBasic> java MultiplicationTable.MultiplicationTable 2 3
 
 or
 
 $ ..\JavaBasic> javac .\MultiplicationTable\MultiplicationTable.java
 $ ..\JavaBasic> java MultiplicationTable.MultiplicationTable 2

package MultiplicationTable;

import java.util.Scanner;

public class MultiplicationTable{
    public static void main(String[] args) {
        if (args.length > 0){
            if (args.length == 2){
                printTable(Integer.parseInt(args[0]), Integer.parseInt(args[1]));
            }
            else printTable(Integer.parseInt(args[0]), 10);
        }
        else {
            Scanner scan = new Scanner ( System.in );
            System.out.print("Enter number (x) = ");
            int x = scan.nextInt ();
            System.out.print("Enter range (limit) = ");
            int limit = scan.nextInt();
            scan.close(); // It's a good habit to close the streams that you opened ;)
            printTable(x, limit);
        }
    }

    public static void printTable(int x, int limit){
        if (limit < 1 || limit > 1000) {
            System.out.println("Limit is less than 1 or exceeding 1000. So, limit is set to 10 by default");
            limit = 10;
        }
        for (int i = 1; i <= limit; i++) {
            System.out.println(x + " x " + i + " = " + (x*i));
            if (i % 10 == 0) System.out.println();
        }
    }
}

import java.util.Scanner; : imports Scanner class from java > util package. Scanner is a class that lets you get input form the user. Scanner can take any primitive data type as input from the user.

public static void main(String[] args) : main method/function is the first method that will be executed in any java programs.

String[] args : args is a array of String type. It is used to get commandline arguments for your program.

args.length > 0 : checks whether args is empty or not

System.out.println(); : Prints the String and changes output cursor to next line

Scanner scan = new Scanner ( System.in ); : scan is an object(a special variable that stores the address in RAM/main memory) of the class Scanner. Here scan acts as the variable that has the access to System.in stream (An input stream that connects keyboard input to the program.

scan.nextInt() : gets Integer input from user.

scan.close(); : closes the input stream link/pipe.

public static void printTable(int x, int limit) : user defined method that prints the multiplication table with the given input data.