a method to check if an input number is integer or float or NAN

[kanakatam]

Hello,
I am working on a program that inputs a data into a textfield and checks if the number is integer, float or Not a number. i have gotten the layout. But i have a rough idea that if it is an integer there would be no decimal points and decimal point for a float data and i fuser enters characters like "A" or "2M" then it's not a number. But this is my first class with strings and so have no idea how to approach this problem. Any guideline appreciated.I have just gotten a layout.

import java.awt.*;
import java.applet.*;
import java.awt.event.*;

public class Lab10a extends Applet
implements ActionListener
{

private TextField inputTF;
private String inputVal;

public void init()
{
Label textLbl = new Label("A program to input a string and display the type of the number");
inputTF = new TextField(7);

add(textLbl);
add(inputTF);

inputTF.addActionListener(this);

}

public void actionPerformed(ActionEvent event)
{
if(event.getSource() == inputTF)
inputVal = inputTF.getText().trim();

repaint();
}


public void paint(Graphics g)
{



}
}


thanx,
kt

[nspils]

the difficulty that I see is deciding on and then implementing the pattern your program will recognize as being an int or a float/double. The String class methods will allow you to distinguish whether a "token" is a number or not. What will involve your own evaluation and implementation will be how your program will decide whether a sting of digits will be interpreted as an integer or a float.

What will be your "sign of the float"? How will you read that from the token?