Thread: Why isn't this working?

import javax.swing.JFrame;
 
 
 
import javax.swing.*;
import java.util.*;
import java.io.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class ScientificNotation extends JFrame
{
 
private JTextField field;
 
public ScientificNotation()
{
setTitle("Scientific Notation");
setVisible(true);
field = new JTextField(25);
setLayout(new GridLayout(2,2));
add(field);
field.setVisible(true);
Container pane = getContentPane();
 
field.addActionListener(new ActionListener() {
 
public void actionPerformed(ActionEvent e)
{
String number = field.getText();
String newString = "";
int digits = 0;
 
if (number.charAt(0) == '0' && number.charAt(1) == '.')
{
for (int i =2; i < number.length(); i++)
{
while (number.charAt(i) == '0')
{
digits--;
}
 
newString = newString + String.valueOf(number.charAt(i));
}
 
JOptionPane.showMessageDialog(null, newString + "E" + digits, "Scientific Notation is:", JOptionPane.INFORMATION_MESSAGE);
}
 
else
{
for (int i = 0; i < number.length(); i++)
{
 
while(number.charAt(i) != '.')
{
digits++;
if (i ==0)
{
newString = newString + String.valueOf(number.charAt(i));
 
}
 
else if (i==1)
{
newString = newString + ".";
}
 
else
{
 
newString = newString + String.valueOf(number.charAt(i));
 
 
}
 
}
newString = newString + String.valueOf(number.charAt(i));
}
JOptionPane.showMessageDialog(null, newString + "E" + digits, "Scientific Notation is:", JOptionPane.INFORMATION_MESSAGE);
}
 
}});
//setContentPane(pane);
}
 
 
public static void main(String[] args)
{
ScientificNotation sn = new ScientificNotation();
 
}
}

How do you get the JTextField to be "normal" sized?

Also, why is my window locking up and the JOptionPane never appearing?

Ok, It's not even going into the loops. I told it to println() the i values and it didn't print anything. The stupid JFrame just turns black and I have to shut it off with the big red button.

Well, these two pictures might help kinda clarify things.

The before and enter are after I hit enter and activate the Action Listener.
Code has been updated.

import javax.swing.JFrame;
import javax.swing.JLabel;
 
 
 
import javax.swing.*;
import java.util.*;
import java.io.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class ScientificNotation extends JFrame
{
 
private JTextField field;
private JLabel notation;
public ScientificNotation()
{
setTitle("Scientific Notation");
setVisible(true);
field = new JTextField(25);
add(field);
notation = new JLabel("Nothing");
add(notation);
field.setBounds(50, 50, field.getPreferredSize().width, field.getPreferredSize().height);
field.setVisible(true);
Container pane = getContentPane();
 
field.addActionListener(new ActionListener() {
 
public void actionPerformed(ActionEvent e)
{
String number = field.getText();
String newString = "";
int digits = 0;
 
if (number.charAt(0) == '0' && number.charAt(1) == '.')
{
for (int i =2; i < number.length(); i++)
{
while (number.charAt(i) == '0')
{
	System.out.println(i);
digits--;
}
System.out.println(i);
newString = newString + String.valueOf(number.charAt(i));
 
}
 
JOptionPane.showMessageDialog(null, newString + "E" + digits, "Scientific Notation is:", JOptionPane.INFORMATION_MESSAGE);
notation.setText(newString + "E" + digits);
}
 
else
{
for (int i = 0; i < number.length(); i++)
{
 
while(number.charAt(i) != '.')
{
digits++;
if (i ==0)
{
newString = newString + String.valueOf(number.charAt(i));
 
}
 
else if (i==1)
{
newString = newString + ".";
}
 
else
{
 
newString = newString + String.valueOf(number.charAt(i));
 
 
}
 
}
newString = newString + String.valueOf(number.charAt(i));
}
JOptionPane.showMessageDialog(null, newString + "E" + digits, "Scientific Notation is:", JOptionPane.INFORMATION_MESSAGE);
notation.setText(newString + "E" + digits);
}
 
}});
//setContentPane(pane);
}
 
 
public static void main(String[] args)
{
ScientificNotation sn = new ScientificNotation();
 
}
}

Also, I might add that I can't exit out of the "Black Screen of Doom" window by hitting the X button or even hitting the Close Window with Windows. I don't mean that the program still runs after I hit the X, I mean the window won't go away, unless I end it by hitting the Terminate button in Eclipse.

Updated again. Still having problems.

import javax.swing.JFrame;
import javax.swing.JLabel;
 
 
 
import javax.swing.*;
import java.util.*;
import java.io.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class ScientificNotation extends JFrame
{
 
private JTextField field;
private JLabel notation;
public ScientificNotation()
{
setTitle("Scientific Notation");
setVisible(true);
field = new JTextField(25);
add(field);
notation = new JLabel("Nothing");
add(notation);
field.setBounds(50, 50, field.getPreferredSize().width, field.getPreferredSize().height);
field.setVisible(true);
Container pane = getContentPane();
 
field.addActionListener(new ActionListener() {
 
public void actionPerformed(ActionEvent e)
{
String number = field.getText();
String newString = "";
int digits = 0;
 
if (number.charAt(0) == '0' && number.charAt(1) == '.')
{
for (int i =2; i < number.length(); i++)
{
while (number.charAt(i) == '0')
{
	System.out.println(i);
digits--;
}
System.out.println(i);
newString = newString + String.valueOf(number.charAt(i));
 
}
 
JOptionPane.showMessageDialog(null, newString + "E" + digits, "Scientific Notation is:", JOptionPane.INFORMATION_MESSAGE);
notation.setText(newString + "E" + digits);
}
 
else if(number.charAt(0) != '0' && (Character) number.charAt(1)!= null)
{
for (int i = 0; i < number.length(); i++)
{
 
while(number.charAt(i) != '.')
{
digits++;
if (i ==0)
{
newString = newString + String.valueOf(number.charAt(i));
 
}
 
else if (i==1)
{
newString = newString + ".";
}
 
else
{
 
newString = newString + String.valueOf(number.charAt(i));
 
 
}
 
}
newString = newString + String.valueOf(number.charAt(i));
}
JOptionPane.showMessageDialog(null, newString + "E" + digits, "Scientific Notation is:", JOptionPane.INFORMATION_MESSAGE);
notation.setText(newString + "E" + digits);
}
else
{
	JOptionPane.showMessageDialog(null, number + "E" + digits, "Scientific Notation is:", JOptionPane.INFORMATION_MESSAGE);
}
 
}});
//setContentPane(pane);
}
 
 
public static void main(String[] args)
{
ScientificNotation sn = new ScientificNotation();
 
}
}

What's going on?

Originally Posted by KevinWorkman

Again: "still having problems" is as useful to us as us saying "then fix it" is useful to you. And again, you're still posting your unwarranted assumptions as advice to other users. Maybe somebody else is up to helping you, but I'm not going to point out your pretty obvious error (which a debugger would show you in about 2 seconds) until you address some of these issues.

I showed what was the problem with the pictures. I thought you'd see them.

Oh, I see, the i value wasn't going up inside the while loop. I feared that might happen, but I didn't know that's what was causing the error. Also, the code still is glitched. It's repeating the first digit a lot of times. By any chance is the String taking in the entire JTextField, including the blank areas? If so, I'll use trim().

What was the try catch for? Also, why is the first digit repeating a bunch of times and then adding that to my exponent?

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
 
public class ScientificNotation extends JFrame {
 
    private JTextField field;
    private JLabel notation;
    private JPanel mypanel;
    private int number2;
    private int power;
    public ScientificNotation() {
        mypanel = new JPanel();
        setTitle("Scientific Notation");
        notation = new JLabel("Nothing");
        field = new JTextField(25);
        mypanel.add(field);
 
        mypanel.add(notation);
        field.setBounds(50, 50, field.getPreferredSize().width, field.getPreferredSize().height);
        add(mypanel);
 
 
        field.addActionListener(new ActionListener()     {
 
            public void actionPerformed(ActionEvent e) {
                try {
                    String number = field.getText().trim();
                    String newString = "";
                    int digits = 0;
 
                    if (number.charAt(0) == '0' && number.charAt(1) == '.') {
                        for (int i = 2; i < number.length(); i++) {
                            while (number.charAt(i) == '0') {
                                System.out.println("i" + i);
                                digits--;
                            }
                            System.out.println("i" + i);
                            newString = newString + String.valueOf(number.charAt(i));
 
                        }
 
                        JOptionPane.showMessageDialog(null, newString + "E" + digits, "Scientific Notation is:", JOptionPane.INFORMATION_MESSAGE);
                        notation.setText(newString + "E" + digits);
                    } else if (number.charAt(0) != '0' && (Character) number.charAt(1) != null) {
                        for (int i = 0; i < number.length(); i++) {
 
                            while (digits < 10) { //while (number.charAt(i) != '.') { <--OLD CODE - WAS REASON FOR ERRORS!
                                digits++;
                                if (i == 0) {
                                    newString = newString + String.valueOf(number.charAt(i));
 
                                } else if (i == 1) {
                                    newString = newString + ".";
                                } else {
 
                                    newString = newString + String.valueOf(number.charAt(i));
 
 
                                }
 
                            }
                            newString = newString + String.valueOf(number.charAt(i));
                        }
                        JOptionPane.showMessageDialog(null, newString + "E" + digits, "Scientific Notation is:", JOptionPane.INFORMATION_MESSAGE);
                        notation.setText(newString + "E" + digits);
                    } else {
                        JOptionPane.showMessageDialog(null, number + "E" + digits, "Scientific Notation is:", JOptionPane.INFORMATION_MESSAGE);
                    }
 
                } catch (StringIndexOutOfBoundsException ex) {
                    System.out.println("Exception Caught Here");
                }
            }
        });
 
 
    }
 
    public void setPower(int power)
    {
    	this.power = power;
    }
 
    public int getPower()
    {
    	return power;
    }
 
    public void setNumber(int number2)
    {
    	this.number2 = number2;
    }
 
    public int getNumber()
    {
    	return number2;
    }
 
    public static void main(String[] args) {
        JFrame sn = new ScientificNotation();
        sn.setSize(500, 200);
        sn.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        sn.setVisible(true);
 
    }
}

Originally Posted by newbie

Well as the code in your for loop is adding onto the String, not replacing, its going to add the value onto the String quite a few times:
newString = newString + String.valueOf(number.charAt(i));

I'll be honest, I haven't read your code to understand what your trying to do, but each pass of loop is adding onto the String instead of replacing.

That's only supposed to be updating the String to include the new char. The String was originally blank and having the text from the JTextField pushed into it one char at a time till the condition is met.

What's happening is that I think in the while loop, the i isn't being updated.
Let me try something....

I see now what might be the problem. The decimal point is never being pushed over.

That and it's sometimes cloning the first digit.