Error during runtime... Exception in thread "main" java.lang.NoSuchMethodEr

Question

I'm fairly new to Java, and admittedly not that great, considering I map my programs out the wrong way - in a VB style procedural basis, so my program probably has newbie "bad programming" things here and there, but that's not the problem.
My program compiles okay in JDK v1.2, but then I try to execute it and it gives me the "main" error message - but I don't have ANYTHING called main - what IS it talking about? All assistance would be greatly appreciated.
Code is below.
Taki
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Assignment1 extends JFrame implements ActionListener
//container components
JLabel introLbl, gameStatusLbl;          
JTextField userInputTxt;               
JButton enter,                    
begin;                    
int x,
userGuess,                    
guessCounter;                    
randomNumber y = new randomNumber();
public Assignment1()
x = y.getNumber();
//setup the container
Container c = getContentPane();
c.setLayout( new FlowLayout() );
introLbl = new JLabel( "Guess my number, between 1 and 1,000 inclusive:" );
c.add( introLbl );
userInputTxt = new JTextField( 4 );
userInputTxt.setEditable( true );
c.add( userInputTxt );
enter = new JButton( "Guess!" );
enter.setActionCommand( "enterCommand" );
enter.addActionListener(this);
c.add( enter );
gameStatusLbl = new JLabel( " " );
c.add( gameStatusLbl );
begin = new JButton( "Begin the game again!" );
begin.setActionCommand( "beginCommand" );
enter.addActionListener(this);
c.add( begin );
public class randomNumber
private int x;
public randomNumber()
x = (int)((Math.random() * 999) + 1);
public int getNumber()
return x;
public void actionPerformed ( ActionEvent e )
String command = e.getActionCommand();
if ( command == "beginCommand" )
x = y.getNumber();
gameStatusLbl.setText( " " );
if ( command == "enterCommand" )
userGuess = Integer.parseInt( userInputTxt.getText() );
if ( userGuess == x )
if ( guessCounter < 10 )
gameStatusLbl.setText( "Well done! " );
else
gameStatusLbl.setText( "You took your time! " );
else
if ( userGuess < x )
if ( guessCounter >= 10 )
gameStatusLbl.setText( "Stop guessing and start thinking! (Too low) " );
else
gameStatusLbl.setText( "Too low. Try again. " );
else
if ( guessCounter >= 10 )
gameStatusLbl.setText( "Stop guessing and start thinking! (Too high)" );
else
gameStatusLbl.setText( "Too high. Try again. " );
guessCounter = guessCounter + 1;
}

Answer 1

This will get you going!
To run a Java app you need a Class whith a 'public static void main(String [] args)' method.
Your window will probably be small, just pull the corner until you figure out hor to get it to display correctly.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Assignment1 extends JFrame implements ActionListener
  //container components
  JLabel introLbl, gameStatusLbl;
  JTextField userInputTxt;
  JButton enter,
  begin;
  int x,
  userGuess,
  guessCounter;
  randomNumber y = new randomNumber();
  public Assignment1() {
      x = y.getNumber();
      //setup the container
      Container c = getContentPane();
      c.setLayout( new FlowLayout() );
      introLbl = new JLabel( "Guess my number, between 1 and 1,000 inclusive:" );
      c.add( introLbl );
      userInputTxt = new JTextField( 4 );
      userInputTxt.setEditable( true );
      c.add( userInputTxt );
      enter = new JButton( "Guess!" );
      enter.setActionCommand( "enterCommand" );
      enter.addActionListener(this);
      c.add( enter );
      gameStatusLbl = new JLabel( " " );
      c.add( gameStatusLbl );
      begin = new JButton( "Begin the game again!" );
      begin.setActionCommand( "beginCommand" );
      enter.addActionListener(this);
      c.add( begin );
  public class randomNumber {
      private int x;
      public randomNumber() {
          x = (int)((Math.random() * 999) + 1);
      public int getNumber() {
          return x;
  public void actionPerformed ( ActionEvent e ) {
      String command = e.getActionCommand();
      if ( command == "beginCommand" ) {
          x = y.getNumber();
          gameStatusLbl.setText( " " );
      if ( command == "enterCommand" ) {
          userGuess = Integer.parseInt( userInputTxt.getText() );
          if ( userGuess == x ) {
              if ( guessCounter < 10 ) {
                  gameStatusLbl.setText( "Well done! " );
              } else {
                  gameStatusLbl.setText( "You took your time! " );
          } else if ( userGuess < x ) {
                if ( guessCounter >= 10 ) {
                    gameStatusLbl.setText( "Stop guessing and start thinking! (Too low) " );
                } else {
                    gameStatusLbl.setText( "Too low. Try again. " );
          } else {
              if ( guessCounter >= 10 ) {
                  gameStatusLbl.setText( "Stop guessing and start thinking! (Too high)" );
              } else {
                  gameStatusLbl.setText( "Too high. Try again. " );
          guessCounter = guessCounter + 1;
    public static void main(String [] args) {
        Assignment1 a = new Assignment1();
        a.show();
}