Simple java issue

Shicky · 26 Apr 2010 at 10:16

Basically I want to be able to call a method i.e. drawCircle in my main method, containing arguements read in through a file. Now I have my main iterating through the data fine. I also have another class called Draw extending JPanel with paintComponent so I have a background on screen. Now I could add to this from the Draw class by typing g.fillOval or whatever but I want to do it from the main as I said above?

This would mean my code would be lots tidier and allow me to have things such as fillOval(array, array[i+1) etc in my main which would be handy.

I know this is a very simple problem, im just brain dead at the moment it seems. Any way to fix this or get around it easily enough?

RobH · 26 Apr 2010 at 10:24

Could you post the code for the classes? This would help as it's not immediately clear what you are trying to do from your description.

Shicky · 26 Apr 2010 at 10:36

Code:

//Research.java

import java.util.*;
import java.io.*;
import javax.swing.*;
import java.awt.*;


public class Research {

	public static void main(String[] args) {
		
		JFrame f = new JFrame("Circuit");
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		Draw d = new Draw();
		f.add(d);
		f.setSize(700, 500);		
		f.setVisible(true);
		
		try
		{
			Scanner s = new Scanner(new File("C:\\Users\\Shicky\\Desktop\\sampleTestData.txt"));
			ArrayList<String> tokens = new ArrayList<String>();
			
			int z = 0;
						
			while(s.hasNext())
			{
				String str = s.nextLine();
				if( str.length() >0)
				{
					String[] p = str.split("\\s+");
					switch (str.charAt(0))
					{
						//case '*': System.out.println("ignore");
						case 'c': 
							z++; 
						    System.out.println(p[0]);
						    
						    break;
						case 'l':
						    
						
					}	
					
				}
			}
			
			System.out.println(z);	
		
			s.close();
			
		}
		catch(Exception e)
		{
			
			System.out.println("Could not open file." );
			e.printStackTrace();
		}
		
	}

}

Code:

//Draw.java

import javax.swing.*;
import java.awt.*;

public class Draw extends JPanel {

	public void paintComponent(Graphics g){
		super.paintComponent(g);
		this.setBackground(Color.WHITE);
	}
			
}

*Sorry that might have been unclear, had to jump out there. Basically in my switch statement when it hits the l case I want it to draw a circle on the canvas. The co-ordinates and additional detail I want to use for labels etc comes from parts of the split string. So essentially right now I can make a circle no problem, but I must do this inside the Draw class. What I want to do is draw a circle from the main class by saying g.fillOval(p[1], [2]) etc? I realise g.fillOval wont work from main but I want to find what will

suarve · 26 Apr 2010 at 13:40

Just out of interest, is this for the HND in computing course? I remember doing something very similar years ago.

Shicky · 26 Apr 2010 at 15:48

suarve said:
Just out of interest, is this for the HND in computing course? I remember doing something very similar years ago.

No mate, this is for my semi-conductor research team in korea lol

SimonCHere · 26 Apr 2010 at 16:00

Why don't you just write drawCircleWithLabels in the draw class and call that?

d.drawCircleWithLabels(p[1],p[2])

Shicky · 26 Apr 2010 at 16:43

SimonCHere said:
Why don't you just write drawCircleWithLabels in the draw class and call that?

d.drawCircleWithLabels(p[1],p[2])

Im not sure I understand you correctly but if so I couldn't access p from the draw class?

Essentially im wondering is there anyway to call the paintComponent/paint methods from outside the draw class i made and if not, any possible solutions anyone sees?

SimonCHere · 26 Apr 2010 at 19:00

no, you write the drawCircleWithLabels in the draw class and as you have an instance of it in the main one, you can reference it and pass it the p[1] variables.

Just call it with

Code:

String[] p = str.split("\\s+");
switch (str.charAt(0))
{
	//case '*': System.out.println("ignore");
	case 'c': 
	    z++; 
	    System.out.println(p[0]);	    
            d.drawCircleWithLabels(p[1],p[2])
            break;
	case 'l':
	   
	
}

You must be able to get create a new graphics instance in the draw class and paint that to the screen?

Something like this.Add(newComponent)

SimonCHere · 26 Apr 2010 at 19:24

New Class

Code:

import javax.swing.*;
import java.awt.*;

class MyOval extends JPanel {

private string _lbl1;
private string _lbl2;

    public MyOval(string lbl1, string lbl2) {
        _lbl1 = lbl1;
		_lbl2 = lbl2;
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);       
		g.drawOval(0, 0, 100, 50);
        // Draw Text
        g.drawString(_lbl1,10,20);
		g.drawString(_lbl2,10,20);
    }  
}

then
Just call it with

Code:

String[] p = str.split("\\s+");
switch (str.charAt(0))
{
	//case '*': System.out.println("ignore");
	case 'c': 
	    z++; 
	    System.out.println(p[0]);	    
            f.add(new MyOval(p[1],p[2]))
            break;
	case 'l':
	   
	
}

No idea if that's syntactically correct as I just dragged bits from the Sun Java site.

Shicky · 27 Apr 2010 at 05:57

That seemed to work and make sense for the most part but when I implemented it, I then had problems with Draw d = new Draw(), it wanted to match the new constructor with labels passed in or for a new constructor completely. This was my attempt but getting all sorts of errors at the moment.

Code:

import java.util.*;
import java.io.*;
import javax.swing.*;
import java.awt.*;


public class Research {

	public static void main(String[] args) {
		
		JFrame f = new JFrame("Circuit");
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		Draw d = new Draw();
		f.add(d);
		f.setSize(700, 500);		
		f.setVisible(true);
		
		try
		{
			Scanner s = new Scanner(new File("C:\\Users\\Shicky\\Desktop\\sampleTestData.txt"));
			ArrayList<String> tokens = new ArrayList<String>();
			
			int z = 0;
						
			while(s.hasNext())
			{
				String str = s.nextLine();
				if( str.length() >0)
				{
					String[] p = str.split("\\s+");
					switch (str.charAt(0))
					{
						//case '*': System.out.println("ignore");
						case 'c': 
							z++; 
						    System.out.println(p[0]);
						    
						    break;
						case 'l':
							f.add(new Draw(p[7], p[8]));				    
						
					}	
					
				}
			}
			
			System.out.println(z);	
		
			s.close();
			
		}
		catch(Exception e)
		{
			
			System.out.println("Could not open file." );
			e.printStackTrace();
		}
		
	}

}

Code:

import javax.swing.*;
import java.awt.*;

public class Draw extends JPanel {
	
	private String _coord1;
	private String _coord2;
	
	public Draw(String coord1, String coord2){
		_coord1 = coord1;
		_coord2 = coord2;		
	}

	public Draw(){
		
	}

	public void paintComponent(Graphics g){
		super.paintComponent(g);
		this.setBackground(Color.WHITE);
		
		g.setColor(Color.GREEN);
		g.drawOval(Integer.parseInt(_coord1), Integer.parseInt(_coord2), 50, 50);
		
	}	
			
}

This cant possibly be as difficult as it seems to draw a circle! Properly stressing me out now

Program runs fine till it gets to the parseInt stage i think and then I get the following errors:

Exception in thread "AWT-EventQueue-0" java.lang.NumberFormatException: null
at java.lang.Integer.parseInt(Unknown Source)
at java.lang.Integer.parseInt(Unknown Source)
at Draw.paintComponent(Draw.java:23)

The full length is rather long but very similar to that involving various paint stuff. Any ideas?

SimonCHere · 27 Apr 2010 at 09:04

I think you might find that the error may be coming from the first
Draw d = new Draw()
line.
You are creating a new instance of the draw class but without the _coord1 values being set.
so when it calls it's own paintComponent it doesn't have anything to draw the oval with. _coord 1 and _coord2 are nothing so parseInt fails.

Either set _coord1 and _coord2 to 0 when they are declared or better yet skip the drawOval if it doesn't have values in either of the _coord variables.

Shicky · 27 Apr 2010 at 16:06

Cheers for you efforts SimonCHere but it became a little muddled for me, found a solution using a Circlelist

Dj_Jestar · 27 Apr 2010 at 17:47

You want everything in main, but at the same time want things kept tidy?

Does not compute

That's a bit of an oxymoron tbh

Shicky · 28 Apr 2010 at 02:15

I wanted to 'call' everything from main just, as I have done, not have everything in the main class

Dj_Jestar · 28 Apr 2010 at 11:18

You're doing a lot more than just calling in Main. You've got lots of logic in there (i.e. your for loops, many if statements, splits etc.)

Shicky · 28 Apr 2010 at 11:40

Ah I suppose, as you can see, im a dire programmer lol