How to use Java command Line Arguments

Whenever we need to pass information into our program during execution ,we can use command line arguments.The Command line arguments are actually the arguments of main() method and are of String Format.Basically command line arguments are those directly follow program's name on the command prompt.As I told earlier that are none other than simple main() programs arguments.All the command line arguments are stored in the form of String.So it is advised to change to required type like integer,char etc before using them in the main program.

Consider below Program as an Example:-

public class CommandArguments{

public static void main(String a[]){

int sum=Integer.parseInt(a[0])+Integer.parseInt(a[1]);

System.out.println("The Sum is :- "+sum);
}
}

As you can see that before adding the command arguments we typecasted them to Integer.This is an operation that is must before any numeric or other data type operation on command arguments.If we would not have typecasted the arguments then the result would be a concatenation of given values,this is because by default the command line arguments are stored as Strings.So it is must to typecast them before their use in application.Java Command Line arguments are mostly useful in command prompt based applications or text based applications.Where there is more of interaction between user and command prompt.

Reading Command Line Arguments:-
We can read command line arguments using the array provided as an argument in main() method.All command line arguments gets stored in that String array.We can use the array reference to point to their values.Lets consider below example:-

public class CmdArg{

public static void main(String arg[]){
  if(arg.length<2){
  for(int i=0;i<2;i++)
  System.out.println("Argument is :- "+arg[i]) 
  }
  else
  System.out.prinltn("Array out of Bound");
 }

}

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