I'm in beginning programming and I don't fully understand applets yet. However, (with some help from internet tutorials) I was able to create an applet that plays a game of guess with the user. The applet compiles fine, but when it runs, this error message appears:
"Exception in thread "main" 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 Guess.createUserInterface(Guess.java:101)
at Guess.<init>(Guess.java:31)
at Guess.main(Guess.java:129)"
I've tried moving the "userguess = Integer.parseInt( t1.getText() );" on line 101 to multiple places, but I still get the same error. Can anyone tell me what I'm doing wrong?
The Code:
// Creates the game GUI.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Guess extends JFrame{
private JLabel userinputJLabel;
private JLabel lowerboundsJLabel;
private JLabel upperboundsJLabel;
private JLabel computertalkJLabel;
private JButton guessJButton;
private JPanel guessJPanel;
static int computernum;
int userguess;
static void declare() {
computernum = (int) (100 * Math.random()) + 1; //random number picked (1-100)
}
// no-argument constructor
public Guess()
{
createUserInterface();
}
// create and position GUI components
private void createUserInterface()
{
// get content pane and set its layout
Container contentPane = getContentPane();
contentPane.setLayout( null );
contentPane.setBackground( Color.white );
// set up userinputJLabel
userinputJLabel = new JLabel();
userinputJLabel.setText( "Enter Guess Here -->" );
userinputJLabel.setBounds( 0, 65, 120, 50 );
userinputJLabel.setHorizontalAlignment( JLabel.CENTER );
userinputJLabel.setBackground( Color.white );
userinputJLabel.setOpaque( true );
contentPane.add( userinputJLabel );
// set up lowerboundsJLabel
lowerboundsJLabel = new JLabel();
lowerboundsJLabel.setText( "Lower Bounds Of Guess = 1" );
lowerboundsJLabel.setBounds( 0, 0, 170, 50 );
lowerboundsJLabel.setHorizontalAlignment( JLabel.CENTER );
lowerboundsJLabel.setBackground( Color.white );
lowerboundsJLabel.setOpaque( true );
contentPane.add( lowerboundsJLabel );
// set up upperboundsJLabel
upperboundsJLabel = new JLabel();
upperboundsJLabel.setText( "Upper Bounds Of Guess = 100" );
upperboundsJLabel.setBounds( 250, 0, 170, 50 );
upperboundsJLabel.setHorizontalAlignment( JLabel.CENTER );
upperboundsJLabel.setBackground( Color.white );
upperboundsJLabel.setOpaque( true );
contentPane.add( upperboundsJLabel );
// set up computertalkJLabel
computertalkJLabel = new JLabel();
computertalkJLabel.setText( "Computer Says:" );
computertalkJLabel.setBounds( 0, 130, 100, 50 ); //format (x, y, width, height)
computertalkJLabel.setHorizontalAlignment( JLabel.CENTER );
computertalkJLabel.setBackground( Color.white );
computertalkJLabel.setOpaque( true );
contentPane.add( computertalkJLabel );
//Set up guess jbutton
guessJButton = new JButton();
guessJButton.setText( "Enter" );
guessJButton.setBounds( 250, 78, 100, 30 );
contentPane.add( guessJButton );
guessJButton.addActionListener(
new ActionListener() // anonymous inner class
{
// event handler called when Guess button is pressed
public void actionPerformed( ActionEvent event )
{
guessActionPerformed( event );
}
} // end anonymous inner class
); // end call to addActionListener
// set properties of application's window
setTitle( "Guess Game" ); // set title bar text
setSize( 500, 500 ); // set window size
setVisible( true ); // display window
//create text field
TextField t1 = new TextField(); // Blank text field for user input
t1.setBounds( 135, 78, 100, 30 );
contentPane.add( t1 );
userguess = Integer.parseInt( t1.getText() );
//create section for computertalk
Label computertalkLabel = new Label("");
computertalkLabel.setBounds( 115, 130, 300, 50);
contentPane.add( computertalkLabel );
}
// Display computer reactions to user guess
private void guessActionPerformed( ActionEvent event )
{
if (userguess > computernum) //if statements (computer's reactions to user guess)
computertalkJLabel.setText( "Computer Says: Too High" );
else if (userguess < computernum)
computertalkJLabel.setText( "Computer Says: Too Low" );
else if (userguess == computernum)
computertalkJLabel.setText( "Computer Says:You Win!" );
else
computertalkJLabel.setText( "Computer Says: Error" );
} // end method oneJButtonActionPerformed
// end method createUserInterface
// main method
public static void main( String args[] )
{
Guess application = new Guess();
application.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
} // end method main
} // end class Phone
