g.drawString not working properly

Jose Muñiz · 10-17-2003, 07:46 AM

My applet calculates two random numbers and lets the user insert a number. The computer checks whether the answer is correct or not, and then writes an appropriate string in the applet.

However, I have two problems:

a) I cannot call method startGame() from init(). Is that normal? If so, what can be done to call methods in the init() method?

b) When I call repaint(), the drawString does not correctly print the message I want. However, the System.out.println's just before repaint(), the same conditionals occur and the message is displayed correctly. I think that might be because repaint() is called too late once the variables' values have been changed? But I'm not sure

I would really appreciate if someone could help me. Thank you very much for reading this.

Code:

import java.awt.*; 
import java.applet.Applet; 


public class Operaciones extends Applet
{

	/* GUI Varibles:				* 
	 * 1. start Button: Starts game 		* 
	 * 2. answerText TextField: Inputs answer	*/
	Button start; 
	TextField answerText; 

	/* User interactive Variables: 			* 
	 * 1. response: Gets answer from answerText	*/
	int answer = 0; 

	/* Non-user  Variables: 			* 
	 * 1. numA: Generates a random number		* 
	 * 2. numB: Generates a random number		*
	 * 3. correct: Says if answer is correct or not */ 
	int numA; 
	int numB; 
	boolean correct = false; 

	boolean firstTime = true; 


	public void init()
 	{
		answerText = new TextField(10); 
		answerText.setEditable(false); 
	

		start = new Button("Start / New!"); 

		add (answerText); 
		add (start); 
	}
	
	public boolean action(Event e, Object o) 
	{

		
		if (e.target == answerText) 		/* User wants to check an answer  		 *
		 					 * methods called to verify existing answers 	 */
		{	
			repaint(); 

			answer = Integer.parseInt(o.toString()); 
			correct = checkGame(answer); 

		}
		else 					/* User wants to start a new game */ 
			startGame(); 

		
		return true; 

		
		
	}

	public void paint(Graphics g) 
	{

		if (correct & !(firstTime)) 
			g.drawString("Correct! You did it!", 25, 125); 
		else if (!(correct) & !(firstTime))
			g.drawString("Try again!", 25, 125); 
	
	}

	public void startGame()
	{
		numA = (int) (Math.random() * 100); 
		numB = (int) (Math.random() * 100); 

		showStatus("How much is " + numA + " times " + numB + " ?"); 
		correct = false; 
		answerText.setEditable(true); 
	}
		
	public boolean checkGame(int checkAnswer)
	{
		firstTime = false; 

		if (numA * numB == checkAnswer)
			correct = true;	

		if (correct & !(firstTime)) 
			System.out.println("Correct! You did it!"); 
		else if (!(correct) & !(firstTime))
			System.out.println("Try again!"); 
			
		repaint(); 
		try 
		{ 
			Thread.sleep(100000);
		}
		catch (InterruptedException e)
		{
		};  

	
		if (correct) 
			startGame(); 
		else 
			showStatus("ERROR: Try again. How much is " + numA + " times " + numB + "?"); 	

		return correct; 
	}
}

nephilim · 10-17-2003, 07:57 AM

Try making your startGame method static like this:

static public void startGame()

You should probably do this for your checkGame method too.

At the end of your paint method, do this:

super.paint(g);

Let me know if this helps.

Jose Muñiz · 10-17-2003, 04:37 PM

No... the super.paint(g) doesn't solve the problem.

About changing the methods to static, my compiler says i cannot use the variables if I use static... should I pass them all as arguments? What would I win by doing so?

Looking_Lost · 10-18-2003, 12:29 PM

I messed about and got it working - at least in the java applet viewer - never done much applets, it doesn't work in IE Explorer (yes stuck on windows at the moment) for reasons unknown to myself. I change it a wee bit but there ya go...could be more elegant....

Code:


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

public class Operaciones extends Applet 
{

	/* GUI Varibles:				* 
	 * 1. start Button: Starts game 		* 
	 * 2. answerText TextField: Inputs answer	*/

        Button myButton; 
	TextField answerText; 

	/* User interactive Variables: 			* 
	 * 1. response: Gets answer from answerText	*/
	
         

	/* Non-user  Variables: 			* 
	 * 1. numA: Generates a random number		* 
	 * 2. numB: Generates a random number		*
	 * 3. correct: Says if answer is correct or not */ 
	
       int numA, numB,correctAnswer,userAnswer; 
       
       boolean correct=false; 

       boolean firstTime=true; 

       String message;
       String questionMessage;    	
   
   ActionListener buttListener=new ActionListener()
     {
      public void actionPerformed(ActionEvent ae)
        {
           if (myButton.getLabel()=="Start") 		
		{	
		  myButton.setLabel("Answer");
                  startGame(); 
                }
            else
                checkGame();
                       

                
          validate(); //Resize button if the label has changed

        }
       };  


      public void init()
 	{
		answerText = new TextField(10); 
		answerText.setEditable(false); 
	

		myButton = new Button("Answer"); 

                myButton.addActionListener(buttListener);

                answerText.setEditable(false);

		this.add(answerText); 

		this.add(myButton); 
               
                startGame();
               
                  
	    }
	


    private void checkGame()
      {

        boolean validNumber=true;

        firstTime=false;
      
        try
         {
           userAnswer = Integer.parseInt(answerText.getText());
          } catch(NumberFormatException nfe) 
                   { validNumber=false;}
           

        if( (validNumber) &  (userAnswer==correctAnswer))
         {

           myButton.setLabel("Start");
           correct=true;

         }           
        else
           {
            answerText.setText("");
            answerText.requestFocus(); 
           } 
       
        repaint();

       }


      private void startGame()
	{
		numA = (int) (Math.random() * 100); 
		numB = (int) (Math.random() * 100); 

                correctAnswer=numA * numB;

                 
                questionMessage=new String("How much is " + numA + " times " + numB + " ?");

 		
                firstTime=true;
                correct = false; 
		
                answerText.setText("");
                answerText.setEditable(true); 
                answerText.requestFocus();         	
                
                repaint();
                  

     }

     
     public void paint(Graphics g) 
	{
            super.paint(g);

            if(correct)  
              {  
               message=new String("Correct ! You did it !");
               questionMessage=new String("Click start to begin"); 
                       
              }
            else
             if(! correct && !firstTime) 
                message=new String("Wrong ! Try again !");
               else
            if(!correct && firstTime) 
               message=new String("");

            g.drawString(message,25,125);
                          
            g.drawString(questionMessage,25,175);		
	
	}

       



}