Java StringTokenizer

[adl_au]

Hello everyone,

I hope this is the right subforum for posting my question.

I need to set up the Java StringTokenizer to read in 4 variables
from a command prompt. It should be in the following format:

>X variable1 variable2 variable3

where

> (is the command prompt)

X (is either +, -, *, /, c, or e)

variable1 variable2 and variable3 are integers.

I will appreciate any answers that will help me go in the right direction.

[ppg]

Hi adl_au,

Welcome to WebmasterWorld!

What are you trying to achieve with the StringTokenizer?

Arguments are accepted by Java programs from the command line through the main(String []) method. The StringTokenizer class takes a single string as an argument and splits it - you seem to want to pass Integers?

Hopefully will be able to help you out with a few more details.

[adl_au]

This code is a rough outline of what I am trying to acheive.

I don't want the program to accept arguments AT the command line. When the program is execute, it should go to a ">" prompt, and allow commands to be entered succively unless "e" is entered. (I know how to implement this).

The program itself is a number base calculator. Two types of instructions can be entered:

c base1 base2 number: instructs the program to convert from the number (an integer) from numberbase1 to numberbase2 (eg >c 10 16 99 would convert from base 10 decimal to base 16 hexdecimal the number 99)

+ (or -, or *, or /) base number1 number 2: performs the arithmatic operation on number1 and number2 in the specified number base (eg >- 10 67 12 would subtract 12 from 67 in base 10).

I don't fully understand how to implement and pass the InputStreamReader to the BufferedReader and then to the StringTokenizer, seperating the 4 components of the string entered.

Thanks for any info!

import java.io.*;
import java.util.*;

public class nbc
{
static public void main(String args[])
{
InputStreamReader stdin = new InputStreamReader(System.in);
BufferedReader console = new BufferedReader(stdin);

StringTokenizer tokenizer;

// parse the string

StringTokenizer tokenizer = new StringTokenizer(commandline, " ");
ArrayList resList = new ArrayList();

while (tokenizer.hasMoreTokens())
{
resList.add(tokenizer.nextToken());
}
}
}

[ppg]

Ah, ok.

Well you can pass the InputStreamReader directly to the BufferdReader when you initialise it:

BufferedReader in = new BufferedReader(new InputStreamReader(System.in));

Then store the input from the BufferReader in a String and pass it over to the StringTokenizer, something like:

String text = "";
try{
 text = in.readLine(); 
 }
 catch(IOException ioe){
 ioe.printStackTrace();
 }
 StringTokenizer tokenizer = new StringTokenizer(text); 
 ArrayList resList = new ArrayList(); 
 while (tokenizer.hasMoreTokens()){ 
 resList.add(tokenizer.nextToken());
 }

Any help?

[danieljean]

adl_au: why are you using a StringTokenizer?

public static void main(String[] args) means you have an array of Strings passed to you. Are the four arguments passed as just one, in quotes?

String first = args[0];
String second = args[1];

etc...

If for some odd reason you absolutely need to use a StringTokenizer, this would be more reasonnable:

try {
String first = tokenizer.nextToken();
//etc...
}
catch (NoSuchElementException nsee)
{
System.out.println("hey, I need four arguments!");
}

HTH