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Thread: Experiencing a run time error, don't know what the problem is

  1. #1
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    Default Experiencing a run time error, don't know what the problem is

    Ok, so in my GUI application, it takes a string and converts it to a number, but there's a problem.

    It generates a run time error

    Here's the cod]
    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;
    public class Season extends JFrame
    		implements ActionListener, KeyListener
    {
    	private JTextField inputTemp, dispSeason;
    	private JButton determ;
    	public Season()
    	{
    		super("Season.java");
     
    		JLabel prompt = new JLabel("Enter a temperature");
    		inputTemp = new JTextField(1);
    		inputTemp.addKeyListener(this);
     
    		JLabel result = new JLabel("The season probably is:");
    		dispSeason = new JTextField(1);
    		dispSeason.setEditable(false);
     
    		determ = new JButton("Determine");
    		determ.addActionListener(this);
     
    		Container c = getContentPane();
    		c.setBackground(Color.white);
     
    		JPanel p = new JPanel();
    		p.setLayout(new GridLayout(4,2));
    		p.add(prompt);
    		p.add(inputTemp);
    		p.add(result);
    		p.add(dispSeason);
    		p.add(determ);
    		c.add(p, BorderLayout.CENTER);
     
    	}
     
    	public void actionPerformed(ActionEvent e)
    	{
     
    		int temp = Integer.parseInt(inputTemp.getText());
    		checkSeason(temp);
     
    	}
     
    	public void keyPressed(KeyEvent e1)
    	{
    		int key = e1.getKeyCode();
    		int temp = Integer.parseInt(inputTemp.getText());
     
    		if(key == KeyEvent.VK_ENTER)
    			checkSeason(temp);
    	}
    	public void keyTyped(KeyEvent e){}
    	public void keyReleased(KeyEvent e){}
     
    	public void checkSeason(int temper)
    	{
     
    		if(temper > 110 || temper < -5)
    			dispSeason.setText("Invalid Temperature");
    		else
    			if(temper >= 90)
    				dispSeason.setText("Summer");
    		else
    			if(temper >= 70 && temper <90 )
    				dispSeason.setText("Spring");
    		else
    			if(temper >= 50 && temper <70)
    				dispSeason.setText("Fall");
    		else
    			if(temper < 50)
    				dispSeason.setText("Winter");
    	}
    	public static void main(String[] args)
    	{
    		Season sea = new Season();
    		sea.setBounds(300,300,400,200);
    		sea.setDefaultCloseOperation(EXIT_ON_CLOSE);
    		sea.setVisible(true);
    	}
    }

    Here's what error says:
    Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: For input string: ""
    	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
    	at java.lang.Integer.parseInt(Integer.java:470)
    	at java.lang.Integer.parseInt(Integer.java:499)
    	at Season.keyPressed(Season.java:49)
    	at java.awt.Component.processKeyEvent(Component.java:6225)
    	at javax.swing.JComponent.processKeyEvent(JComponent.java:2801)
    	at java.awt.Component.processEvent(Component.java:6044)
    	at java.awt.Container.processEvent(Container.java:2041)
    	at java.awt.Component.dispatchEventImpl(Component.java:4630)
    	at java.awt.Container.dispatchEventImpl(Container.java:2099)
    	at java.awt.Component.dispatchEvent(Component.java:4460)
    	at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1850)
    	at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:712)
    	at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:990)
    	at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:855)
    	at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:676)
    	at java.awt.Component.dispatchEventImpl(Component.java:4502)
    	at java.awt.Container.dispatchEventImpl(Container.java:2099)
    	at java.awt.Window.dispatchEventImpl(Window.java:2478)
    	at java.awt.Component.dispatchEvent(Component.java:4460)
    	at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
    	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
    	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
    	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
    	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
    	at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

    Thank you if you can help.


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Experiencing a run time error, don't know what the problem is

    NumberFormatException: For input string: ""
    at java.lang.NumberFormatException.forInputString(Num berFormatException.java:48)
    at java.lang.Integer.parseInt(Integer.java:470)
    at java.lang.Integer.parseInt(Integer.java:499)
    at Season.keyPressed(Season.java:49)
    Look at line 49 in Season.java where the call to parseInt is made and see why the arg for the method is ""

    For example:
    Integer.parseInt(inputTemp.getText());

    Do this in two steps. Get the contents of the text field and validate it before trying to use it.

  3. The Following User Says Thank You to Norm For This Useful Post:

    scooty199 (October 3rd, 2010)

  4. #3
    Junior Member
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    Default Re: Experiencing a run time error, don't know what the problem is

    I did find my error. I realized in my keyPressed method I should have out the parseInt under the if condition.

    Thanks for the help!

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