Tokenizer

[skaterboy987]

I'm writing a program to reverse whatever words you enter... Here is the result I would like to have

My input: input1 input2 input3
Wanted Output:
input1
input2
input3


Yes I have looked at the person's topic who was attempting the same thing, but it didn't really help for my problem
Here's my result with what I have:

My input:input1 input2 input3
output: null
output: input3
output: input2
output: Exception in thread "main" java.lang.NullPointerException
at Token.main(Token.java:23)

import java.util.Scanner;
import java.util.StringTokenizer;


public class Token {

	 public static void main(String args[]) {
		 int i = 0;
		 String[] token;              // declares an array of integers
         token = new String[5];      // allocates memory for 10 integers
         Scanner scanner = new Scanner(System.in);
        String text = scanner.nextLine();
    StringTokenizer st = new StringTokenizer(text);
 
    while (st.hasMoreTokens()) 
    {
        i++;
		token[i] = st.nextToken();
		
 }
	for(int x=1; x<=(token.length- 1); x++)
	{
		if (token[x].equalsIgnoreCase("null") ) {
		}
		else
		{
		System.out.println(token[token.length - x]);
		}
	}
}
}

[Fubarable]

Use println's to tell you what's going on:

    while (st.hasMoreTokens()) 
    {
        i++;
        token[i] = st.nextToken();
        System.out.println("i is: " + i + "; and token[i] is: " + token[i]);
     }

This may give you a hint as to what your problem is (hint look carefully at i's value).

[Fubarable]

Also:

public class Token {

	 public static void main(String args[]) {
		 int i = 0;
		 String[] token;              // declares an array of integers  *** WTF? ***
         token = new String[5];      // allocates memory for 10 integers  *** WTF? ***
         Scanner scanner = new Scanner(System.in);
        String text = scanner.nextLine();
    StringTokenizer st = new StringTokenizer(text);
 
    while (st.hasMoreTokens()) 
    {
        i++;
		token[i] = st.nextToken();
		
 }
	for(int x=1; x<=(token.length- 1); x++)
	{
		if (token[x].equalsIgnoreCase("null") ) {   // *** WTF? ***
		}
		else
		{
		System.out.println(token[token.length - x]);
		}
	}
}
}

• Use String#split(...) if you can instead of a StringTokenizer. That way you'll be able to create an array of the right size no matter what text is entered
• Be sure your comments agree with your code!
• Never check for null that way lest you want to have lots of NPE's thrown. You would do it as if (token[i] == null) {
• Please be compulsive about using proper code indentation and consistent formatting, including curly brace formatting. Coding is an exercise in precision and there's no place in it for sloppiness. This will also cut down on the number of code errors you produce.

[kennyman94]

why not just read the entire text file into one string, call its split(String regex) method, and then iterate over the returned array in a reversed for-loop (start at a number then decrement to 0)? if you want to seperate each token by whitespace, then just call:
String[] tokens = text.split(" ");

[Junky]

why not just read the entire text file into one string

Not a good idea when dealing with large files. You will run out of memory.

[kennyman94]

I would think it would be pretty hard to run out of memory with a String. the JFugue api uses Strings to represent notes, chords, durations, etc. for midi and it can use Miles of characters in a single String (from what i hear anyways)

[Junky]

I have a crappy application at work that reads files and is constantly running out of memory when it tries to read large files.

[kennyman94]

interesting....