Thread: StringTokenizer error

I am having trouble using the StringTokenizer class in following code.

import java.util.*;
 
class ParseEval
{
     public static void main (String args[])
          {
               if (args.length == 0)
               {
                    System.out.println("No arguments entered");
               }
               else if (args.length == 1)
               {
                    StringTokenizer argsToks = new StringTokenizer(args, "+");
 
                    while(argsToks.hasMoreTokens())
                    {
                         System.out.print(argsToks.nextToken());
                         System.out.println();
                    }
               }
               else
               {
                    System.out.println(args.length);
               }
          }
}

When I try to compile it, I get the following error:

ParseEval.java:18:cannot find symbol
symbol: constructor StringTokenizer (java.lang.String[], java.lang.string)
location: java.util.StringTokenizer
                     StringTokenizer argsToks = new StringTokenizer(args, "+")
                                                                          ^

I though I had imported the correct packages, but I'm not sure I have.

You need to look at the error message more closely. Especially this line:
constructor StringTokenizer (java.lang.String[], java.lang.string)
Then you need to read the API doc for StringTokenizer and check the syntax for its Constructors.

Originally Posted by Norm

You need to look at the error message more closely. Especially this line:
constructor StringTokenizer (java.lang.String[], java.lang.string)
Then you need to read the API doc for StringTokenizer and check the syntax for its Constructors.

I did read the API doc, and I thought that I was using the StringTokenizer(String str, String delim), which I thought was the correct syntax for what I wanted to do.

it is giving error "cannot find symbol" for String Tokenizer.

Please copy full text of error message and paste it here. Here is a sample:

TestSorts.java:138: cannot find symbol
symbol : variable var
location: class TestSorts
var = 2;
^

Originally Posted by mjpam

I am having trouble using the StringTokenizer class in following code.

import java.util.*;
 
class ParseEval
{
     public static void main (String args[])
          {
               if (args.length == 0)
               {
                    System.out.println("No arguments entered");
               }
               else if (args.length == 1)
               {
                    StringTokenizer argsToks = new StringTokenizer(args, "+");
 
                    while(argsToks.hasMoreTokens())
                    {
                         System.out.print(argsToks.nextToken());
                         System.out.println();
                    }
               }
               else
               {
                    System.out.println(args.length);
               }
          }
}

When I try to compile it, I get the following error:

ParseEval.java:18:cannot find symbol
symbol: constructor StringTokenizer (java.lang.String[], java.lang.string)
location: java.util.StringTokenizer
                     StringTokenizer argsToks = new StringTokenizer(args, "+")
                                                                          ^

I though I had imported the correct packages, but I'm not sure I have.

I'm wondering, can a does it have to be ClassName[] referenceVariable = new ClassName[3];
or can it be ClassName referenceVariable[] = new ClassName[3] ?

If it does have to do, then does it have to be

String[] args or is String args[] fine?

Also, was args ever set for anything because it'll throw a NullPointerException if it hasn't been with the statement StringTokenizer argsToks = new StringTokenizer(args, "+");

Also, args is an array.

Wait, I see the problem....

The constructors for StringTokenizer are:

StringTokenizer(String str)

StringTokenizer(String str, String delim)

StringTokenizer(String str, String delim, boolean returnDelims)

args is an array.

The constructor StringTokenizer(String[] args, String str) isn't valid.

Maybe args[0] as that's an element.

You could try

String str = args[0].toString(); // that'll work for sure, especially if args[0] is some value other than a String

maybe just

String str = args[0];

will work.



StringTokenizer argsToks = new StringTokenizer(str, "+");

Do you have a java programming question?

Well, I was trying to answer the question of what might be causing the problem. Also, do you know what a Document Listener is? I need one to be able to get it to add a listener, or at least use the setSelected() method on an item in a JComboBox which itself has an Item Listener, based on what is in the text field.

do you know what a Document Listener is

Have you looked in the Tutorial or the API doc?

Originally Posted by Norm

Have you looked in the Tutorial or the API doc?

I kinda did, but not much. However, I cannot get an addDocumentListener() method for a JTextField or a JTextArea or even a JFrame.

I cannot get an addDocumentListener() method for a JTextField

That's correct there isn't one.
In the API doc page at the top of the page is a link: Index click that. On the index page, click on the first letter of the method here 'a', scroll down or find the method(s) then follow the link to the class with that method.

Originally Posted by Norm

That's correct there isn't one.
In the API doc page at the top of the page is a link: Index click that. On the index page, click on the first letter of the method here 'a', scroll down or find the method(s) then follow the link to the class with that method.

I don't see how this would work with a JTextField. Also, couldn't I just add Key Listeners?

Also, there is an addKeyListener() method for JTextField.

Also, couldn't I use fireActionPerformed() to activate the Item Listener?

However, I'll create one of them Document thingies to see what it'll do.

How do you get it to activate a Key Listener if the user types in say 12 or makes a capital letter, say L(Shift + l)
, or ! (Shift + 1), or enters 124 or something or types Bob or something like that?

Put together an example program with a text field and a Document listener and post it here with your questions.

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.KeyEvent;
 
import javax.swing.event.MenuEvent;
import javax.swing.event.MenuListener;
import javax.swing.event.PopupMenuEvent;
import javax.swing.event.PopupMenuListener;
import javax.swing.text.DefaultStyledDocument;
 
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.ScrollPaneConstants;
 
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
import java.util.*;
import java.io.*;
import javax.swing.ImageIcon;
 
 
import java.awt.event.WindowEvent;
import java.awt.Window;
import javax.swing.JScrollPane;
import java.awt.Component;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
 
public class thisClass extends JFrame
{
 
JTextField cornField, beanField;
JFrame frame;
DefaultStyledDocument doc;
 
public thisClass()
{
frame = new JFrame("This is the JFrame I'm using.");
doc = new DefaultStyledDocument();
 
cornField = new JTextField(3);
beanField = new JTextField(3);
 
frame.add(cornField);
frame.add(beanField);
 
frame.setVisible(true);
cornField.setVisible(true);
beanField.setVisible(true);
 
doc.addDocumentListener(
new DocumentListener() {
public void changedUpdate(DocumentEvent e)
{
 
}
 
public void insertUpdate(DocumentEvent e)
{
 
}
 
public void removeUpdate(DocumentEvent e)
{
 
}
 
 
}
);
}
 
public static void main(String[] args)
{
thisClass refVar = new thisClass();
 
}