Sample Questions for the Mid-Term Exam

Answer each of the following in the space provided:

From the standpoint of a software engineer, carefully and concisely define the term "computer".

(1)

From the standpoint of a software engineer, what differentiates a "mobile computer" from any other "computer".

(2)

In J2ME, what is a "profile"?

(3)

What is BREW?

(4)

Why are traditional GUI tool/widget sets (e.g., AWT, Swing) not appropriate for many mobile computing devices?

(5)

Draw a state chart/diagram (prefereably in UML) that includes both states and transitions for a J2SE application.
Create a J2ME Displayable that, when displayed, will look something like the following:
Modify your answer to the question above so that the user can both clear the phrase and translate the phrase. Your implementation must:
1. Use Command objects.
2. Have (and use) a clearPhrase() method that clears the phrase.
3. Have (and use) an empty translatePhrase() method that is passed String objects for the two languages and the phrase to be translated.
Write a Translator class that can be used to translate a phrase in a separate thread of execution. (Note: You should not implement a working translation algorithm. The translation algorithm should simply append the String "[translated]" to the phrase.
Implement the translatePhrase() method. Your implementation must:
1. Construct a local Translator() object.
2. Use the local Translator() object to perform the translation in a separate thread of execution.
List two techniques that can be used to reduce the number of objects that must be created in the translatePhrase() method aboce. Discuss the advantages and disadvantages of each. Which would you use?
Implement your preferred solution to the previous question.

The application in class Question below uses the two classes TickReader and TickWriter. Trace the execution of this application by writing numbers/letters next to each line indicating the thread it is executed in and the order in which it is executed. Lines in the first thread should be numbered using 1,2,3... Lines in the second thread (if there is one) should be numbered using A,B,C... Lines in the third thread (if there is one) should be numbered using a,b,c...

  import java.io.*;



  /**
   * The application
   *
   */
  public class Question
  {


    /**
     * The entry point of the application
     *
     * @param args   The array of command-line arguments
     */
    public static void main(String[] args)
    {
        BufferedReader  br;
        FileReader      fr;
        PrintWriter     pw;
	TickReader      in;
	TickWriter      file, screen;




	try {

            fr = FileReader("question.tik");
            br = new BufferedReader(fr);
            in = new TickReader(br);

            pw = new PrintWriter(System.out, true);

            screen = new TickWriter(pw);

            in.setTickObserver(screen);

            in.readTick();

            screen.start();

            in.readTick();


	} catch (Exception exception) {

	    System.err.println(exception);
	}
    }
  }

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

  /**
   * A class for reading Tick information from a BufferedReader
   *
   */
  public class TickReader
  {
    protected BufferedReader   reader;
    protected TickWriter       observer;



    /**
     * Construct a new TickReader
     *
     * @param reader   The BufferedReader to read from
     */
    public TickReader(BufferedReader reader)
    {
	this.reader = reader;
	observer = null;
    }



    /**
     * Set the observer
     *
     * @param observer      The new observer
     */
    public void setTickObserver(TickWriter observer)
    {
	this.observer = observer;
    }




    /**
     * Notify the observer of a Tick
     *
     * @param tick          The tick to notify them of
     */
    public void notifyTickObserver(String tick)
    {
	observer.handleTickNotification(tick);
    }




    /**
     * Read one Tick object and notify the observer
     *
     */
    public void readTick() throws IOException
    {
	String tick;

	tick = reader.readLine();
	notifyTickObserver(tick);
    }
  }

  import java.io.*;
  import java.util.*;
  /**
   * A class for writing Tick information to a PrintWriter
   */
  public class TickWriter implements Runnable
  {
    protected LinkedList    queue;
    protected PrintWriter   writer;
    protected Thread        ctrl;

    /**
     * Construct a new TickWriter
     *
     * @param Writer   The BufferedWriter to use
     */
    public TickWriter(PrintWriter writer)
    {
	this.writer = writer;
	queue = new LinkedList();
        ctrl = new Thread(this)
    }


    /**
     * Handle notification from a TickReader
     *
     * @param tick      The tick to be handled
     */
    public void handleTickNotification(String tick)
    {
	queue.addLast(tick);
    }


    /**
     * Print the tick on the writer
     *
     * @param tick  The tick to print
     */
    private void printTick(String tick)
    {
	writer.println(tick);
    }


    /**
     * Code to run in the control thread
     */
    public void run()
    {
	String    tick;

	if (queue.size() > 0) {

	    tick = (String)(queue.removeFirst());
	    printTick(tick);
	}
    }
  }


  /**
   * Starts the control Thread
   */
  public void start()
  {
      ctrl.start();
  }

The file question.tik contains the following information:

    MSFT,STOCK,129.175,b
    C1997Z,FUTURE,253.3,a
    MSFT,STOCK,130.175,s