Question

Not sure if it will actually be more optimized, however What I am trying to do is take all of this code and possibly split it up within different classes? So far it is all just one class but We have been leaning more and more to multiple class projects so I am trying to figure out how I can split this and actually have it help rather then just splitting stuff up to split it up. Any help would be great!

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.util.*;


public class PaintProgram extends JPanel implements MouseListener,ActionListener 
{
  private int xX1, yY1 , xX2, yY2, choice ;

  public static void main(String [] args)
  {
      new PaintProgram();
  }

  PaintProgram()
  {


    JFrame frame = new JFrame("Paint Program");
    frame.setSize(1200, 800);
    frame.getContentPane().add(this);

    JButton button1 = new JButton("Clear");
    button1.addActionListener(this);
    JButton button2 = new JButton("Filled rectangle");
    button2.addActionListener(this);
    JButton button3 = new JButton("Filled oval");
    button3.addActionListener(this);
    JButton button4 = new JButton("Empty rectangle");
    button4.addActionListener(this);
    JButton button5 = new JButton("Empty oval");
    button5.addActionListener(this);
    JButton button6 = new JButton("Line");
    button6.addActionListener(this);


    this.add(button1); 
    this.add(button2);
    this.add(button3);
    this.add(button4);
    this.add(button5);
    this.add(button6);
    addMouseListener(this);

    frame.setVisible(true);     
}

public void paintComponent(Graphics g)
{ 
     super.paintComponent(g);  
     Graphics2D g2 = (Graphics2D)g;
     if(grid == null){
        int w = this.getWidth();
        int h = this.getHeight();
        grid = (BufferedImage)(this.createImage(w,h));
        gc = grid.createGraphics();
     }
     g2.drawImage(grid, null, 0, 0);
     check();
}
BufferedImage grid;
Graphics2D gc;


public void draw()
{
    Graphics2D g = (Graphics2D)getGraphics();
     int w = xX2 - xX1;
        if (w<0)
        w = w *(-1);

   int h = yY2-yY1;
        if (h<0)
        h=  h*(-1);

     switch(choice)
    {
        case 1:
            check();
            gc.setColor(Color.YELLOW);
            gc.drawRect(xX1, yY1, w, h);
            repaint();
            break;

        case 2:
            check();
            gc.setColor(Color.CYAN);
            gc.drawOval(xX1, yY1, w, h);
            repaint();
            break;

        case 3:
            check();
            gc.setColor(Color.ORANGE);
            gc.drawRect(xX1, yY1, w, h);
            gc.fillRect(xX1, yY1, w, h);
            repaint();
            break;

        case 4:
            check();
            gc.drawOval(xX1, yY1, w, h);
            gc.setColor(Color.PINK);
            gc.fillOval(xX1, yY1, w, h);
            repaint();
            break;  

        case 5:
            check();
            gc.setColor(Color.MAGENTA);
            gc.drawLine(xX1, yY1, xX2, yY2);
            repaint();
            break;

        case 6:
            //Acquire clear screen or gay
            break;   
    }
}

public void check()
{
    if (xX1 > xX2)
    {
        int z = 0;
        z = xX1;
        xX1 = xX2;
        xX2 =z;
    }
    if (yY1 > yY2)
    {
        int z = 0;
        z = yY1;
        yY1 = yY2;
        yY2 = z;
    }
}



public void actionPerformed(ActionEvent e)
{

if (e.getActionCommand().equals("Empty rectangle")) 
{         
  System.out.println("Empty Rectangle Has Been Selected~");
   choice = 1;

  }

if (e.getActionCommand().equals("Empty oval")) 
{         
 System.out.println("Empty Oval Has Been Selected!");
   choice = 2;
  }


if (e.getActionCommand().equals("Filled rectangle"))
{         
  System.out.println("Filled Rectangle Has Been Selected");
   choice = 3;
  }


if (e.getActionCommand().equals("Filled oval")) 
{         
 System.out.println("Filled Oval Has Been Selected");
   choice = 4;
  }


if (e.getActionCommand().equals("Line"))
{
    System.out.println("Draw Line Has Been Selected");
    choice = 5;
}

if (e.getActionCommand().equals("Clear"))
{         
 System.out.println("Clear All The Things!!!");
   choice = 6;
   repaint();
  }

 }

 public void mouseExited(MouseEvent evt){}
 public void mouseEntered(MouseEvent evt){}
 public void mouseClicked(MouseEvent evt){}
 public void mousePressed(MouseEvent evt)
 {

     xX1 = evt.getX();
     yY1= evt.getY();

   }
 public void mouseReleased(MouseEvent evt)
 {
     xX2 =evt.getX();
     yY2=evt.getY();
     draw();
   }
}

Answer 1

I would do it like this:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;


public class PaintProgram extends JPanel implements MouseListener 
{
    private int xX1, yY1 , xX2, yY2;
    private PaintOperation currentOperation;
    private void setCurrentOperation(PaintOperation po) { currentOperation = po; }

    private class PaintOperation {
        private int choice;
        public PaintOperation(final PaintProgram context, String text, int choice) {
            this.choice = choice;
            final JButton button = new JButton(text);
            button.addActionListener(new ActionListener() {
                public void actionPerformed(ActionEvent e) {
                    context.setCurrentOperation(PaintOperation.this);
                    context.repaint();
                    System.out.println("PaintOperation: "+button.getText());
                }
            });
            context.add(button);
        }
    }

    public static void main(String [] args)
    {
        new PaintProgram();
    }

    PaintProgram()
    {
        JFrame frame = new JFrame("Paint Program");
        frame.setSize(1200, 800);
        frame.getContentPane().add(this);

        new PaintOperation(this, "Empty rectangle", 1);
        new PaintOperation(this, "Empty oval", 2);
        new PaintOperation(this, "Filled rectangle", 3);
        new PaintOperation(this, "Filled oval", 4);
        new PaintOperation(this, "Line", 5);
        setCurrentOperation(new PaintOperation(this, "Clear", 6));

        addMouseListener(this);

        frame.setVisible(true);     
    }

    public void paintComponent(Graphics g)
    { 
        super.paintComponent(g);  
        Graphics2D g2 = (Graphics2D)g;
        if (grid == null) {
            int w = this.getWidth();
            int h = this.getHeight();
            grid = (BufferedImage)(this.createImage(w,h));
            gc = grid.createGraphics();
        }
        g2.drawImage(grid, null, 0, 0);
        check();
    }
    BufferedImage grid;
    Graphics2D gc;


    public void draw()
    {
        Graphics2D g = (Graphics2D)getGraphics();
        int w = xX2 - xX1;
        if (w<0)
            w = w *(-1);

        int h = yY2-yY1;
        if (h<0)
            h=  h*(-1);

        switch(currentOperation.choice)
        {
        case 1:
            check();
            gc.setColor(Color.YELLOW);
            gc.drawRect(xX1, yY1, w, h);
            repaint();
            break;

        case 2:
            check();
            gc.setColor(Color.CYAN);
            gc.drawOval(xX1, yY1, w, h);
            repaint();
            break;

        case 3:
            check();
            gc.setColor(Color.ORANGE);
            gc.drawRect(xX1, yY1, w, h);
            gc.fillRect(xX1, yY1, w, h);
            repaint();
            break;

        case 4:
            check();
            gc.drawOval(xX1, yY1, w, h);
            gc.setColor(Color.PINK);
            gc.fillOval(xX1, yY1, w, h);
            repaint();
            break;  

        case 5:
            check();
            gc.setColor(Color.MAGENTA);
            gc.drawLine(xX1, yY1, xX2, yY2);
            repaint();
            break;

        case 6:
            //Acquire clear screen or gay
            break;   
        }
    }

    public void check()
    {
        if (xX1 > xX2)
        {
            int z = 0;
            z = xX1;
            xX1 = xX2;
            xX2 =z;
        }
        if (yY1 > yY2)
        {
            int z = 0;
            z = yY1;
            yY1 = yY2;
            yY2 = z;
        }
    }

    public void mouseExited(MouseEvent evt){}
    public void mouseEntered(MouseEvent evt){}
    public void mouseClicked(MouseEvent evt){}
    public void mousePressed(MouseEvent evt)
    {
        xX1 = evt.getX();
        yY1= evt.getY();
    }
    public void mouseReleased(MouseEvent evt)
    {
        xX2 =evt.getX();
        yY2=evt.getY();
        draw();
    }
}