Command line applications

Question

Hi,
does anybody know how to create a class that represents a command line application that would use a previously created class's methods and variables?
Jamie

Answer 1

Is this what you're after?
You can compile these 2 together as is with InUser.java - though better to compile the class In.java seperately then you will be able to use it elsewhereimport java.io.*;
// Note: this class has NO "main()" so it cannot work alone
class In{
   private static InputStreamReader isr = new InputStreamReader(System.in);
   private static BufferedReader in = new BufferedReader(isr);
   public static void prompt(String s) {
      System.out.print(s);
      System.out.flush();
   public static String getString(){
      String str = null;
      try {
         str = in.readLine();
      catch (IOException e){
         System.out.println("Error: In.Read() "+e.getMessage());
         System.exit(0);
   return str;
   public static int getInt(){
      int ii = 0;
         try {
         ii = Integer.parseInt(in.readLine() );
      catch (NumberFormatException nfe){
         System.out.println("Error: the number is not convertable to an int");
      catch (IOException e){
         System.out.println("Error: In.Read() "+e.getMessage());
         System.exit(0);
   return ii;
   public static double getDouble(){
      double dd = 0D;
         try {
            dd = Double.parseDouble(in.readLine() );
         catch (NumberFormatException nfe){
            System.out.println("Error: the number is not convertable to a double");
         catch (IOException e){
            System.out.println("Error: In.Read() "+e.getMessage());
            System.exit(0);
   return dd;
// And the user with file with a main signature:
public class InUser{
   public static void main(String[]args){
      System.out.println("\nExample 'In.java' with Readln:");
      In.prompt("Please enter your name: ");
      String name = In.getString();
      System.out.println("Welcome "+name); 
      In.prompt("Please enter a whole number: ");  
      int ii = In.getInt();
      System.out.println("The number squared is "+(ii*ii)); 
      In.prompt("Please enter a fraction number: ");  
      double dd = In.getDouble();
      System.out.println("The numbers square root is " +Math.sqrt(dd));    
}