Assignment Project Source Code

Assignment source code

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

public class Draw extends Applet 
  implements MouseListener, ActionListener {

  Vector drawnShapes = new Vector();
  Choice shapeChoice;
  CheckboxGroup group = new CheckboxGroup();
  Button save;
  Button restore;
  public static void main(String args[]) {

    Frame frame = new Frame("Draw");
    Draw draw = new Draw();

    draw.init();
    frame.add("Center", draw);
    frame.setSize(500,500);
    frame.show();
  frame.addWindowListener(new WindowHandle());
  }      

 
  public void init() {
    Checkbox checkbox;
    setLayout(new BorderLayout());     

    Panel p = new Panel();

    shapeChoice = new Choice();
    shapeChoice.addItem("Circle");
    shapeChoice.addItem("Square");
    p.add(shapeChoice);

    save = new Button("save");
    p.add(save);
    save.addActionListener(this);

    restore = new Button("restore");
    p.add(restore);
    restore.addActionListener(this);

    add("North", p);

    p = new Panel();

    checkbox = new Checkbox(null, group, true);
    checkbox.setBackground(Color.red);
    p.add(checkbox);

    checkbox = new Checkbox(null, group, false);
    checkbox.setBackground(Color.blue);
    p.add(checkbox);

    checkbox = new Checkbox(null, group, false);
    checkbox.setBackground(Color.green);
    p.add(checkbox);

    add("South", p);
    addMouseListener(this);
  }

  public void actionPerformed(ActionEvent e) {
    if(e.getSource() == save) writeToStream();
    if(e.getSource() == restore) {
      drawnShapes.removeAllElements();
      readFromStream();
    }
  }

  public void mousePressed(MouseEvent mouse_evt) {
    int x = mouse_evt.getX();
    int y = mouse_evt.getY();

    Checkbox checkbox;
    Shape s;

    String shapeString = shapeChoice.getSelectedItem(); 
    if (shapeString.equals("Circle"))
       s = new Circle();
    else
       s = new Square();
    
    checkbox = group.getSelectedCheckbox();
    s.color = checkbox.getBackground();

    s.x = x;
    s.y = y;

    drawnShapes.addElement(s);
    repaint();
  }

  // other methods for MouseListener
  
  public void mouseClicked(MouseEvent mouse_evt){
    // do nothing
  }

  public void mouseEntered(MouseEvent mouse_evt){
    // do nothing
  } 
  
  public void mouseExited(MouseEvent mouse_evt){
    // do nothing
  }  
  
  public void mouseReleased(MouseEvent mouse_evt){
  }

  public void paint(Graphics g) {

   Shape s;
   Enumeration e = drawnShapes.elements();

   while (e.hasMoreElements()) {
      s = (Shape)e.nextElement();
      s.draw(g);
     }
   }

 
  void writeToStream() {
    DataOutputStream out = null;
    try {
      out = createOutputStream();
      writeNumShapes(out);

      Shape s;
      Enumeration e = drawnShapes.elements();

      while (e.hasMoreElements()) {
        s = (Shape)e.nextElement();
        s.out(out);
      }  
    } 
    catch (NullPointerException x) {
      System.out.println("Null Pointer Exception 1");
    } 
    catch (IOException x) {
      System.out.println("IO Exception: " + x.getMessage());
    }
    finally {
      try {
        out.close();
      } 
      catch (IOException x) {
      }
    }
  }

 
  void readFromStream() {
    Shape s;  
    DataInputStream in = null;

    try {
      in = createInputStream();
      int num = readNumShapes(in);
      for (int i = 0; i < num; i++) {
        int type = readShapeType(in);
        if (type == Shape.CIRCLE)
          s = new Circle();
        else
          s = new Square();         

        s.in(in);
        drawnShapes.addElement(s);
      }    
    } 
    catch (NullPointerException x) {
      System.out.println("Null Pointer Exception");
    } 
    catch (IOException x) {
      System.out.println("IO Exception: " + x.getMessage());
    }

    finally {
      try {
        in.close();
      } 
      catch (IOException x) {
      }
      repaint();
    }
  }

  DataOutputStream createOutputStream() throws IOException {
  }
  DataInputStream createInputStream() throws IOException {
  }
  void writeNumShapes(DataOutputStream out) throws IOException {    
  }
  int readNumShapes(DataInputStream in) throws IOException { 
  }
  int readShapeType(DataInputStream in) throws IOException {
  }
}

 
abstract class Shape {
  static int CIRCLE = 1;
  static int SQUARE = 2;

  static int RED = 1;
  static int BLUE = 2;
  static int GREEN = 3;

  Color color;
  int x;
  int y;
  int width = 20;

  abstract void draw(Graphics g);

  void writeIntToStream(DataOutputStream out, int i)
   throws IOException {
    out.writeInt(i);
  }

  int readIntFromStream(DataInputStream in)
   throws IOException {
    return in.readInt();
  }

  void in(DataInputStream in) throws IOException {
    int c = readIntFromStream(in);
    if (c == RED)
      color = Color.red;
    else 
      if (c == BLUE)
        color = Color.blue;
      else
        color = Color.green;

    x = readIntFromStream(in);
    y = readIntFromStream(in);
  }

 
  void out(DataOutputStream out) throws IOException {
    if (color == Color.red)
      writeIntToStream(out, RED);
    else 
      if (color == Color.blue)
        writeIntToStream(out, BLUE);
      else
        writeIntToStream(out, GREEN);

    writeIntToStream(out, x);
    writeIntToStream(out, y);
  }
}

class Circle extends Shape {
  void draw(Graphics g) {
    g.setColor(this.color);
    g.fillOval(x, y, width, width);
  }

  void out(DataOutputStream out) throws IOException {
    writeIntToStream(out, CIRCLE);
    super.out(out);
  }
}

class Square extends Shape {
  void draw(Graphics g) {
    g.setColor(this.color);
    g.fillRect(x, y, width, width);
  }

  void out(DataOutputStream out) throws IOException {
    writeIntToStream(out, SQUARE);
    super.out(out);
  }
}
class WindowHandle extends WindowAdapter

{
 public void windowClosing(WindowEvent e)
  {
  System.exit(0);
  }
}