1.124J Foundations of Software Engineering

Problem Set 6 - Solution

Due Date: Thursday 11/2/00
 
The solution source code files are available in the 1.124 directory from where you can check them out using CVS. Please read and try to understand the solutions.

The solution source code files are in the source code repository directory /mit/1.124/src from where you can check them out to your directory using CVS.

To use CVS to check out any provided material from the 1.124 repository you first need to set the environment variable CVSROOT as below: (you can also put it in your .environment dotfile to avoid repetition)

% setenv CVSROOT /afs/athena.mit.edu/course/1/1.124/src

Then you can use either of the commands:

%  cvs co Problems/SOL6

% cvs co OOP_SOL6
(alias defined in 1.124/src/CVSROOT/modules)

Problem 1:[60%]

Part A:

Sol6_1.java

public class Sol6_1a
{
   public static void main(String args[])
    {
      new Plotter1();
    }
}
 
 

plotter.java

import java.io.*;
import java.util.*;

public class Plotter1
{
 Plotter1()
 {
   readData();
 }
 
 void readData()
  {
   FileInputStream ifp;
   double x[], y[];
      x = y = null;
 
      String fileName =  new String("data6_1");

      try{
           ifp = new FileInputStream(fileName);
         }
      catch(FileNotFoundException e)
         {
            System.out.println(" File " + fileName + " was not found.");
            return;
      }
 
      int i, n=0;

      InputStreamReader rd = new InputStreamReader(ifp);
      StreamTokenizer tk = new StreamTokenizer(rd);

      try {
             tk.nextToken();
             n = (int)tk.nval;
             x = new double[n];
             y = new double[n];

             for(i=0;i<n;i++)
                {
                   tk.nextToken();
                   x[i] = (double)tk.nval;
                   tk.nextToken();
                   y[i] = (double)tk.nval;
                }
             ifp.close();
           }
         catch(IOException e)
           {
             System.out.println("IOException: " + e.getMessage());
           }
         System.out.println("\n" + n + " points have been read");
              for(i=0;i<n;i++)
                {
                  System.out.print("x[" + (i+1) +"]=" + x[i]);
                  System.out.println("\ty[" + (i+1) +"]=" + x[i]);
                }
  }
}

Part B:

Sol6_1.java

public class Sol6_1
{
   public static void main(String args[])
    {
      new Plotter();
    }
}
 
 

plotter.java

import javax.swing.*;

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

public class Plotter extends JFrame
                     implements ActionListener
{
   private JMenuBar menuBar ;
   private JMenu fileMenu;
   private JMenuItem importMI, exitMI;
 
   private JToolBar toolBar = new JToolBar();
   private JButton dashedButton, solidButton;
   private JPanel contentPane;
 
   private Plot plot;
 
   String fileName;
   FileInputStream ifp =null;
 
   public Plotter()
    {
    super("Problem Set 6 - Problem 3: Plotter");
       JPopupMenu.setDefaultLightWeightPopupEnabled(false);
       setSize(500,500);

    setMenuBar();
    contentPane = new JPanel() ;
    contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.Y_AXIS));
    setToolBar();
    setPlot();
 
    setContentPane(contentPane);
 

    setVisible(true);

       addWindowListener(new WindowAdapter()
                     {
                 public void windowClosing(WindowEvent e)
                         {
          dispose(); System.exit(0);
          }
                     }                     );
   }

 private void setMenuBar()
   {
       menuBar = new JMenuBar();
 
       fileMenu = new JMenu("File");
       menuBar.add(fileMenu);
       importMI = new JMenuItem("Import Data");
       importMI.addActionListener(this);
       fileMenu.add(importMI);
       exitMI = new JMenuItem("Exit");
       exitMI.addActionListener(this);
       fileMenu.add(exitMI);
 
    setJMenuBar(menuBar);
   }
 
 private void setToolBar()
   {
    toolBar = new JToolBar();
 
    dashedButton = new JButton(new ImageIcon("dashed.gif"));
    dashedButton.setMnemonic(KeyEvent.VK_D);
    dashedButton.setToolTipText("Dashed line");
    dashedButton.addActionListener(this);
    toolBar.add(dashedButton);
    toolBar.addSeparator();
 
    solidButton = new JButton(new ImageIcon("solid.gif"));
    solidButton.setMnemonic(KeyEvent.VK_S);
    solidButton.setToolTipText("Solid line");
    solidButton.addActionListener(this);
    toolBar.add(solidButton);
    toolBar.addSeparator();
 
    contentPane.add(toolBar);
   }
 
private void setPlot()
  {
      plot = new Plot();
   contentPane.add(plot);
  }
 
  public void actionPerformed(ActionEvent evt)
   {
    Object src = evt.getSource();

    if(src == exitMI)
      System.exit(0);
 else if (src == importMI)
    readData();
 else if (src == dashedButton)
      plot.setStroke(Plot.dashedStroke);
 else if (src == solidButton)
      plot.setStroke(Plot.solidStroke);
   }
 
  void readData()
  {
   double x[], y[];
      x = y = null;
 
      fileName =  new String("data6_1");

      try{
           ifp = new FileInputStream(fileName);
         }
      catch(FileNotFoundException e)
         {
            System.out.println(" File " + fileName + " was not found.");
            return;
      }
 
      int i, n=0;

      InputStreamReader rd = new InputStreamReader(ifp);
      StreamTokenizer tk = new StreamTokenizer(rd);

      try {
             tk.nextToken();
             n = (int)tk.nval;
             x = new double[n];
             y = new double[n];

             for(i=0;i<n;i++)
                {
                   tk.nextToken();
                   x[i] = (double)tk.nval;
                   tk.nextToken();
                   y[i] = (double)tk.nval;
                }
             ifp.close();
           }
         catch(IOException e)
           {
             System.out.println("IOException: " + e.getMessage());
           }
         System.out.println("\n" + n + " points have been read");
      for(i=0;i<n;i++)
            {
               System.out.print("x[" + (i+1) +"]=" + x[i]);
               System.out.println("\ty[" + (i+1) +"]=" + x[i]);
            }
   plot.setPoints(x,y);
     }
 
}

plot.java

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.text.*;
import java.awt.geom.*;
 

public class Plot extends JPanel
{
 final static float dash[] = {10.0f};
    final static BasicStroke dashedStroke = new BasicStroke(1.0f,
                                                      BasicStroke.CAP_BUTT,
                                                      BasicStroke.JOIN_MITER,
                                                      10.0f, dash, 0.0f);
    final static BasicStroke solidStroke = new BasicStroke(1.0f);
    BasicStroke stroke = solidStroke;
 
 double x[]=null, y[]=null;
    int xx[], yy[];
 double minX, maxX, minY, maxY;
 
 public Plot()
      {
   super();
 
         setBackground(Color.blue);
      setForeground(Color.black);
  }
 
 void setStroke(BasicStroke s)
 {
   stroke = s;
   repaint();
 }
 
     public void paintComponent(Graphics g)
    {
   super.paintComponent(g);
         Graphics2D g2 = (Graphics2D) g;
         int h = getHeight();
   int w = getWidth();
   int i, x1, y1, x2, y2, n;
   double absMaxY;
 
   if(x==null)
    return;
 
   n = x.length;
 
   x1 = (int)(w*0.1);
   x2 = (int)(w*0.9);
   y1 = y2 = h/2;
 
   g2.setStroke(solidStroke);
   g2.drawLine(x1, y1, x2, y2);
   g2.drawString("x="+minX,(int)(w*0.01), (int)(h*0.51));
   g2.drawString("x="+maxX,(int)(w*0.91), (int)(h*0.51));
   g2.drawString("y="+maxY,(int)(w*0.05), (int)(h*0.10));
   g2.drawString("y="+minY,(int)(w*0.05), (int)(h*0.95));

   g2.setStroke(stroke);
 
   if(Math.abs(maxY)>Math.abs(minY))
      absMaxY = Math.abs(maxY);
   else
      absMaxY = Math.abs(minY);
 
  for(i=0;i<n;i++)
      {
     xx[i] = (int) (x1 + (x[i]-minX)/(maxX-minX)*0.8*w);
     yy[i] = (int) (y1 - y[i]/absMaxY * 0.4 * h);
      }
 
   g2.drawPolyline(xx, yy, xx.length);

    }
 
 void setPoints(double x[], double y[])
 {
  int i , n ;
 
  n = x.length;
  this.x = new double[n];
  this.y = new double[n];
  xx = new int[n];
  yy = new int[n];
 
  maxX = x[0];
  minX = x[0];
  maxY = y[0];
     minY = y[0];
 
        for(i=0;i<n;i++)
      {
               this.x[i] = x[i];
      if(maxX < x[i])
       maxX = x[i];
      else if(minX > x[i])
       minX = x[i];
 
      this.y[i] = y[i];
      if(maxY < y[i])
       maxY = y[i];
      else if(minY > y[i])
       minY = y[i];
        }
  repaint();
 }
 
}

Problem 2:[35%]

Sol6_2.java

public class Sol6_2
{
    public static void main(String[] args)
          {
               CreditCardAccount x1 = new CreditCardAccount(32483273, 0.00, 10000.00);
      System.out.println("\nNewly created credit card account:\n" + x1);
               System.out.println();
               CreditCardAccount x2 = new CreditCardAccount(93455454, 250.75, 5000.00);
               System.out.println("Newly created credit card account:\n" + x2 + "\n");

               ThreadGroup g = new ThreadGroup("Thread Group X");

               CreditCardTranscationsThread t1 = new CreditCardTranscationsThread(x1, g, "Thread t1");
               CreditCardTranscationsThread t2 = new CreditCardTranscationsThread(x2, g, "Thread t2");

               CreditCardTransactionsRunnable r1 = new CreditCardTransactionsRunnable(x1);
               CreditCardTransactionsRunnable r2 = new CreditCardTransactionsRunnable(x2);

               Thread t3 = new Thread(r1);
               Thread t4 = new Thread(r2);

      System.out.println("ThreadGroup: " + g);
      System.out.println("Thread: " + t1);
      System.out.println("Thread: " + t2);
      System.out.println();

      System.out.println("ThreadGroup: " + t3.getThreadGroup());
      System.out.println("Thread: " + t3);
      System.out.println("Thread: " + t4);
      System.out.println();

      t1.start();
               t2.start();
       t3.start();
               t4.start();
            }
}

CreditCardAccount.java

import java.text.*;
import java.io.* ;

class CreditCardAccount
{
    private int creditID;
    private double currentBalance;
    private double allowableLimit;
    static private DecimalFormat df = new DecimalFormat("##,##0.00");
    FileOutputStream ofp;
 byte tmpByte[];
 String tmpStr;

 CreditCardAccount(int creditID, double currentBalance,
                     double allowableLimit)
    {
          this.creditID = creditID;
          this.currentBalance = currentBalance;
          this.allowableLimit = allowableLimit;
    File file = new File("c" + creditID);

    try
    {
       ofp = new FileOutputStream(file);
    }
         catch( FileNotFoundException e)
          {
             System.out.println(" File " + file + " could not be opened.");
          }
    }
 

 double getCurrentBalance()
    {
           return currentBalance;
    }

 double getAllowableLimit()
    {
           return allowableLimit;
    }
 

    synchronized void charge(double amount)
      {

      if(confirmation(amount))
     {
              currentBalance += amount;
              tmpStr = "Account has been charged an amount of $"
                        +  df.format(amount) + "\n";
     }
     else
     {
       tmpStr = "The amount $" + df.format(amount) +
        " was not authorized to be charged \n";
     }

      tmpStr += "   Account: " + this + "\n";
         tmpStr += "   By the Thread: " + Thread.currentThread() + "\n";
   tmpStr += "   of the ThreadGroup: " + Thread.currentThread().getThreadGroup() + "\n";

   try
      {
      tmpByte = tmpStr.getBytes();
      ofp.write(tmpByte);
         }
       catch(java.io.IOException e)
      {
       System.out.println("Unable to write to file: " );
            }
      }
 

 boolean confirmation(double amount)
 {
    try{
                Thread.sleep((int)(100*Math.random()));
             }
          catch(InterruptedException e)
             {
                System.out.println("Catch InterruptedException in run(): "
                                               + "\n" + e.getMessage());
             }

    if(currentBalance+amount < allowableLimit)
     return true;
    else
     return false;
 }
 

    synchronized void payment(double amount)
      {
          currentBalance -= amount;
          tmpStr = "A payment of " + df.format(amount) + " has been made\n";

    tmpStr += "   Account: " + this + "\n" ;
          tmpStr += "   By the Thread: " + Thread.currentThread() + "\n";
    tmpStr += "   of the ThreadGroup: " + Thread.currentThread().getThreadGroup() + "\n";

    try
      {
      tmpByte = tmpStr.getBytes();
      ofp.write(tmpByte);
         }
       catch(java.io.IOException e)
      {
       System.out.println("Unable to write to file: " );
            }
      }
 

    synchronized public String toString()
       {
           return ("   Credit card number = " + creditID +
       "   Current Balance = " + df.format(currentBalance)+
       " Limit = " +  df.format(allowableLimit));
       }

}
 
 

CreditCardTranscationsThread.java

class CreditCardTranscationsThread extends Thread
{
    private CreditCardAccount account;

    CreditCardTranscationsThread(CreditCardAccount account,
                ThreadGroup threadGroup, String threadName)
       {
          super(threadGroup, threadName);
          this.account = account;
       }

    public void run()
       {
          for (int i=0; i<10; i++)
         {
        try{
                       Thread.sleep((int)(100*Math.random()));
                    }
                 catch(InterruptedException e)
                    {
                      System.out.println("Catch InterruptedException in run(): "
                                                  + "\n" + e.getMessage());
                    }
                  account.charge(Math.random()*account.getAllowableLimit());
                  account.payment(Math.random()*account.getCurrentBalance());
    }
      }
}
 
 

CreditCardTransactionsRunnable.java

class CreditCardTransactionsRunnable implements Runnable
{
    private CreditCardAccount account;

    CreditCardTransactionsRunnable(CreditCardAccount account)
       {
          this.account = account;
       }

    public void run()
       {
          for (int i=0; i<10; i++)
         {
        try{
                       Thread.sleep((int)(100*Math.random()));
                    }
                 catch(InterruptedException e)
                    {
                      System.out.println("Catch InterruptedException in run(): "
                                                  + "\n" + e.getMessage());
                    }
                  account.charge(Math.random()*account.getAllowableLimit());
                  account.payment(Math.random()*account.getCurrentBalance());
    }
      }
}

 



© 1.124J Foundations of Software Engineering
Prof. Kevin Amaratunga,1-274, kevina@mit.edu
Prof. John R. Williams,  1-250, jrw@mit.edu
TA: Petros Komodromos, 1-245, petros@mit.edu