why this is not equal

[ibrahim yener]

Could someone please explain me why following code always return false.

private int		question = 0;
private String 	answer   = "";

// Variable of " answer " retrieve data by textField.getText(); method

private void checkAnswer()
{
	int x = 0;
	x = Integer.parseInt (answer);
		
	if(question == x)
		System.out.println ("Equal");
	else
		System.out.println ("no it is not");
}

[Jayesh A Lalwani]

You can find out by printing the value of x

[ibrahim yener]

The output is equal

System.out.println(question);
10
System.out.println(x);
10

The question is definitely an Integer value
but i am not sure Integer.parseInt (answer); is really converting into Integer

[fred rosenberger]

I'm not sure, but try printing a character before your output...something like

System.out.println(":" + x + ":");

it is possible there is whitespace that you are just not seeing.

[ibrahim yener]

i changed my code into textField.getText().trim(); and still same.

[Campbell Ritchie]

As well as that, please explain how that code compiles in the first place.

[ibrahim yener]

Dear Campbell Ritchie
Here is entire Code.

import java.awt.*;

import java.util.Random;

import javax.swing.*;
import javax.swing.border.EmptyBorder;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class BasicMath extends JFrame
{
	private static final long	serialVersionUID	= 3587097960096123604L;
	private JPanel			contentPane		= new JPanel ();
	private JTextField		textField			= new JTextField ();
	private JLabel			lblNewLabel		= new JLabel ();
	private JButton			btnNewButton		= new JButton ("Answer");
	private Random			randNum			= new Random ();
	private int				question			= 0;
 	private String 			answer			= "";

	public static void main(String[] args)
	{
		EventQueue.invokeLater (new Runnable ()
 		{
			 public void run()
			{
				BasicMath frame = new BasicMath ();
				frame.setVisible (true);

			 }
  		});
	 }

	 public BasicMath ()
 	{
		setResizable (false);
 		setAlwaysOnTop (true);
		setDefaultCloseOperation (JFrame.DISPOSE_ON_CLOSE);
		setBounds (700, 425, 500, 375);

		contentPane.setBorder (new EmptyBorder (5, 5, 5, 5));
		setContentPane (contentPane);
		contentPane.setLayout (null);

		btnNewButton.addActionListener (new ActionListener ()
		{
			public void actionPerformed(ActionEvent arg0)
			{
				setComponents();
				checkAnswer();
			}
 		 });

		btnNewButton.setFont (new Font ("Tahoma", Font.BOLD, 30));
		btnNewButton.setBounds (93, 254, 282, 48);
		contentPane.add (btnNewButton);

		setComponents();
	   }
	
	private void setComponents()
	{
		//	Adding TextField
		textField.setHorizontalAlignment (SwingConstants.CENTER);
		textField.setFont (new Font ("Tahoma", Font.BOLD, 30));
		textField.setBounds (93, 166, 282, 48);
		contentPane.add (textField);
		textField.setColumns (10);
		//	Getting Value of TextField
		cevap = textField.getText ().trim();
		//	Reset TextField to null
		textField.setText (null);
 	}

	private String getQuestion()
	{
		int firstNumber = randNum.nextInt (10);

		if(firstNumber == 0)
			firstNumber = 1;

		int secondNumber = randNum.nextInt (10);

		if(secondNumber == 0)
			secondNumber = 1;
		
		this.question = firstNumber + secondNumber;

		return firstNumber + " + " + secondNumber;
	 }

	private void checkAnswer()
	{
		int x = 0;
		x = Integer.parseInt (answer);
		
		if(question == x)
			System.out.println ("it is equal");
		else
			System.out.println ("No it is not");
	 }
}

[Jesper de Jong]

When you run that, you should see a NumberFormatException happen in line 95, because answer is "" (empty string).

In line 19, you are initializing answer to "" but nowhere else in your code you are assigning the value entered in a text field to answer.

[ibrahim yener]

Dear Jesper
Sorry it is my fault, i forgot rename it at line 70.

cevap = textField.getText ().trim();

should be

answer = textField.getText ().trim();

[Campbell Ritchie]

Jesper is right and I was mistaken; it will fail at run‑time with that Exception, not at compile‑time.

[ibrahim yener]

Okay guys
First of all, i want to thank to whom tried to help me.

Finally i found problem and fixed it. I am going to describe problem and provide solution and hopes this helps somebody else.

Problem caused by line #49 (calling setComponents method setComponents();) because whenever user hit the answer button
program generates new random number but user's entered value still keeps old one so checkAnswer(); method always try to compare new code and old code therefor it always return false.


Solution was simple: Removed setComponents(); method call at line #49 and place it bottom of checkAnswer(); method.
When program checks user's answer than call setComponents(); method.

Hope this help someone else too.

Appreciate for help.

Regards