Program -1 Reverse String with input String from arguments
public class ReverseString{

public static void main(String args[]){

ReverseString obj = new ReverseString();
System.out.println(obj.reverseString(args[0]));
}


public String reverseString(String str){

String aux = "";
for(int itr = str.length()-1;itr>=0;itr--){
aux += str.charAt(itr);
}
return aux;
}



}
Running the program as : java ReverseString ekiras 
Output of the program : sarike


Program -2 : Reverse String with input from command line at runtime.
import java.io.*;

public class ReverseString{

public static void main(String args[]){

ReverseString obj = new ReverseString();
System.out.println(obj.reverseString(obj.getStringFromUser()));
}


public String reverseString(String str){

String aux = "";
for(int itr = str.length()-1;itr>=0;itr--){
aux += str.charAt(itr);
}
return aux;
}

public String getStringFromUser(){

try{
System.out.println("Enter String to be reversed");
BufferedReader br= new BufferedReader(new InputStreamReader(System.in));
return br.readLine();
}
catch(Exception e){e.printStackTrace();}
return "ekansh";
}



}

Output of the above program :
Enter String to be reversed
ekiras

sarike