Faculty Of Computer Studies M257. Putting Java to Work. Final Examination/ General MOCK / An. Semester: Date:

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1 Faculty Of Computer Studies M257 Putting Java to Work Final Examination/ General MOCK / An Semester: Date: nswer Key Number of Exam Pages: (?) Time Allowed: ( 3 ) Hours Instructions: 1. This exam has 3 parts and ALL questions must be answered. 2. Write your answer in the answer booklets. Answers given on the exam paper will not be marked. 3. Student handbooks are NOT permitted in this examination. 4. The use of electronic devices that could have a memory is NOT permitted. 5. At the end of the examination, check that you have written your student ID, name and your section number on the first page. من ثلاث أجزاء وجميع 1. هذا الامتحان مكون اسي لتها مطلوب حلها. 2. الاجابة تكون على كراسة الاجابات علما با نه لن معطاه على ورقة يتم تصحيح اي اجابات الا سي لة كتب او مذكرات الى قاعة 3. ممنوع اصطحاب اي الامتحان. 4. ممنوع استخدام اي اجهزة الكترونية بها ذاكره. 5. في نهاية الامتحان تا كد من كتابة اسمك و رقمك الجامعي و رقم شعبتك على كلا من كراسة الاجابة و ورقة الامتحان. M257 Final Exam / General MOCK Page 1

2 -The exam consists of three parts. -All questions should be solved. Exam Guidelines -The total grade is displayed in the title of each question along with the estimated time for an average level of students to solve. -The provided questions are presented in actual past exams. -They are considered as samples of what could be expected. This file does not include the actual questions and the actual number of the questions of the real final exam. The Exam Structure is: -Part 1: MCQ questions covering all chapters -Part 2: Essay questions & short problem solving covering all chapters -Part 3: Problem solving and writing codes covering all chapters All best of luck; M257 Final Exam / General MOCK Page 2

3 PART1: Choose the correct answer and write it on the answer sheet: (15 marks- 1.5 marks for each correct answer 20 minutes) Choose the correct answer and write it on the external answer booklet. 1. Which of the following reads Java bytecode files and displays the corresponding source code? a. Java interpreter c. Java debugger b. Java compiler d. Java disassembler 2. Which of the following do not store data but are used to point to objects? a. Primitive variables c. Reference variables b. Instance variables d. Static variables 3. Which of the following could be used to define the start and end of a code block in Java? a. [ ] c. { b. ( ) d. < > 4. is a sequence of bytes, representing a flow of data from a source to a destination. a. Bytecode c. Event handling b. Stream d. Source code 5. Which of the following is used to encapsulate primitive data types and allow them to be treated as objects? a. Generic classes c. Interfaces b. Adapter classes d. Object wrapper classes 6. Which of the following is a Java package used for GUI design in Java? a. java.gui c. java.utils b. javax.swing d. java.net 7. Which of the following methods moves a Java thread from running state to blocked state? a. yield() c. block() b. sleep() d. destroy() 8. Which of the following is a ServerSocket method which listens for a connection to be made to this socket and accepts it? a. listen() c. socket() b. wait() d. accept() 9. Which of the following is stored and run on a web server? a. Applets c. Midlets b. Servlets d. None of the above 10. Which of the following methods passes HTTP requests to helper methods in a Java servlet? a. inti() c. doget() b. dooptions() d. service() M257 Final Exam / General MOCK Page 3

4 Part 2: Essay questions & Short Problem Solving (35 marks 60 minutes) 1. Why is it usual to create constructors as public? When should constructors be created as private? We create constructors as public because it is usual that we want to create objects from outside the class in which we define them. We make constructors as private if we want to make it illegal to create objects of the type outside the defining class. e.g. Math class 2. List three similarities between Java interfaces and abstract classes. They can both place requirements on objects of other classes. Both can have abstract methods (although neither needs have abstract methods). You cannot create objects of an abstract class type or an interface type. You can, create reference variables of either type. Both can inherit: the abstract class from another class; the interface only from another interface. 3- What is the difference between mutator and accessor methods? Mutator Methods: have an effect on the state of the object Accessor Methods: methods correspond to a simple request for information and cannot alter the state of the object. [2 marks] 4- What is the difference between applications and applets? Applications: are stand-alone programs, which can run independently. Applets are programs that can be included in web documents and are run using browsers 5 -Trace the following code, what will the output be? And then re-write the main method by replacing for loop by do.. while loop public class Q3 { public static int t1=3; public static void main(string[] args) { int t2=1; System.out.println("t1="+ t1); System.out.println("t2="+ t2); for (int i=1; i<7; i++) { t1 *= i; t2= test(t1); if (t1 > 60) break; // main method public static int test(int c) { System.out.println("t1= " +t1); // class return t1*c; The answer as: M257 Final Exam / General MOCK Page 4

5 t1=3 t2=1 t1= 3 t1= 6 t1= 18 t1= 72 The main method code by replacing for loop by do.. while loop public static void main(string[] args) { int t2=1; System.out.println("t1="+ t1); System.out.println("t2="+ t2); int i=1; do { t1 *= i; t2= test(t1); if (t1 > 60) break; i++; while (i<7); // main M257 Final Exam / General MOCK Page 5

6 Part 3: Problem Solving: Part 3- Q1 (50 marks 100 minutes) Develop a Java program that includes the following: (a) An interface ShipInterface that includes a method: public void moveto(double latitude, double longitude). When this method is implemented in any class, it should set the position of the relevant object to given values (b) A public class Position that: - has two private instance variables of the type double: latitude and longitude. - has setter methods for both latitude and longitude. - overrides the Object s tostring() method in order to return a string representation of the object s state; for example, "Latitude: 10.4, Longitude= 30.2" (c) A public class Ship that: - It implements ShipInteface. - has an instance variable items which is an array of String objects. - has an instance variable position of the type Position (the class you wrote in (b)). - has a two-argument constructor that sets the value of items and position to given values. - overrides the Object s tostring() method in order to return a string representation of the object s state; for example, "Latitude: 10.4, Longitude= 30.2, Number of items: 5" - implements any additional required methods The answer as: (a) public interface ShipInterface { public void moveto(double latitude, double longitude); (b) public class Position { private double latitude, longitude; public void setlatitude(double l) {latitude = l; public void setlongitude(double l) {longitude = l; public String tostring(){ return "Latitude: " + latitude + ", Longitude: " + longitude; (c) public class Ship implements ShipInterface{ public String[] items; public Position position; public Ship(String[] items, Position position) { this.items = items; this.position = position; public void moveto(double lat, double lon){ position.setlatitude(lat); position.setlongitude(lon); public String tostring(){ return position.tostring() + "Number of Items: " + items.length; M257 Final Exam / General MOCK Page 6

7 Part 3- Q2 Write a Java program to the following specifications: The program has to read many lines from the first file (c:/file1.txt) Then, it has to write the lines that ONLY contains the String AOU in the second file (c:/file2.txt) Calculate the number of copied lines and print it at the end in finally clause Use try catch statement to handle any exception of the type Exception, and display a simple error message in case an exception happens. You don t need to write any import statements. Hint: may the following methods are useful to solve this question, chartat(), substring(); indexof(), length(), equals(). public class Q3_P3 { public static void main (String[] args){ int counter=0; try { File readerfile = new File ("C:/file1.txt "); Scanner sc = new Scanner (readerfile); File writerfile = new File ("C:/file2.txt "); PrintWriter pw= new PrintWriter(writerFile); System.out.println("Now we are going to read from the file "); String line; do{ line=sc.nextline(); if (line.indexof("aou")!= -1) { pw.println(line); counter++; while (sc.hasnext()); //close scanner sc.close(); pw.close(); // try catch (Exception e) // class { System.out.println(); finally { System.out.println(counter + " lines are copied"); M257 Final Exam / General MOCK Page 7

8 Part 3- Q3 You are required to add code to the following code skeleton so that when the run method is invoked, the client reads a text file and sends its contents to a server, line by line. And once the client finishes that, a notification is shown to the user, e.g. Message sent successfully. Your code should handle the IOException within the run method, and show a simple error message in case an exception is triggered. In your solution, assume that the path of the file to be sent is c:/test.txt, and that the server is located at IP address and listening to port number Hint: you might find the following Java methods useful: close(), println(), nextline(), hasnextline(), getoutputstream(). public class Client { public void run() { // ADD CODE HERE! public static void main(string[] args) { Client c = new Client(); c.run(); try { Socket socket = new Socket(" ", 3333); PrintWriter toserver = new PrintWriter(socket.getOutputStream()); Scanner in = new Scanner(new File("c:/test.txt")); while (in.hasnextline()) { toserver.println(in.nextline()); in.close(); toserver.close(); socket.close(); System.out.println("Message sent!"); catch (IOException e) { System.out.println("I/O Error!"); M257 Final Exam / General MOCK Page 8

9 Part 3- Q4 Consider the following code and answer the questions about it, assuming necessary libraries are imported public class Q4 extends JFrame{ private JLabel namel; private JLabel choicel; private JTextField namet; private JRadioButton rbt1; private JRadioButton rbt2; private JRadioButton rbt3; private ButtonGroup itemsg; private JPanel p1 private JButton btn1; private JButton btn2; private JButton btn3; private JPanel p2; //Part 1 write the constructor //Part 3 add the action listener to the buttons private class ButtonHandler implements ActionListener{ public void actionperformed(actionevent e) { //Part 2 the actions should be done public static void main (String[] args){ // Part 4 instantiate the Jframe Develop a Java program that includes the following: Part1: Write the constructor of the class which contains the following specifications: - Set the size 300x300, and the title My Final Exam and it has a border layout - It has 2 panels; - The first includes the label, the text field and the button group. - The second includes the 3 buttons, show, save in file and exit - Create the components of the frame as in figure 1 Hint: You are required to use the same name of the components of the JFrame Part2: write the code of the buttons as the following specifications: - If the user clicks on Show button, it will display his name and his choice in a dialogue box. - If the user clicks on Save in file button, it will write his name and his choice on the file "C:/FinalFall13.txt" and display Successfully Saved in a dialogue box. - If the user clicks on Exit button, it will close the Jframe and the program will terminate. Part3: write the code that adds the action listener to the buttons Part4: write the code that instantiates the Jframe M257 Final Exam / General MOCK Page 9

10 //Part 1 answer public Q4 (){ setsize(300, 300); settitle("my Final Exam"); Container cp=getcontentpane(); cp.setlayout(new BorderLayout()); namel= new JLabel("Enter Your Name: "); namet= new JTextField (20); choicel= new JLabel("Select Your Choice: "); rbt1= new JRadioButton ("Tea", true); //initially selected rbt2 = new JRadioButton("Coffee", false); rbt3 = new JRadioButton("Espresso ", false); itemsg = new ButtonGroup(); itemsg.add(rbt1); itemsg.add(rbt2); itemsg.add(rbt3); p1 = new JPanel(new GridLayout(6, 1)); p1.add(namel); p1.add(namet); p1.add(choicel); p1.add(rbt1); p1.add(rbt2); p1.add(rbt3); cp.add(p1, BorderLayout.NORTH); btn1= new JButton("Show"); btn2= new JButton("Save in File"); btn3= new JButton("Exit"); p2 = new JPanel(new GridLayout(1, 3)); p2.add(btn1); p2.add(btn2); p2.add(btn3); cp.add(p2, BorderLayout.SOUTH); //Part 3 answer btn1.addactionlistener( new ButtonHandler ()); btn2.addactionlistener( new ButtonHandler ()); btn3.addactionlistener( new ButtonHandler ()); rbt1.addactionlistener ( new ButtonHandler ()); rbt2.addactionlistener ( new ButtonHandler ()); rbt3.addactionlistener ( new ButtonHandler ()); Part 2 answer public void actionperformed (ActionEvent e){ Object smart=e.getsource(); String ch1=""; if (rbt1.isselected() ) ch1= rbt1.gettext(); else if (rbt2.isselected() ) ch1= rbt2.gettext(); else if (rbt3.isselected() ) ch1= rbt3.gettext(); String message= "Welcome " + namet.gettext() + " Your choice is " + ch1; M257 Final Exam / General MOCK Page 10

11 if (smart.equals(btn1)) { JOptionPane.showMessageDialog(null, message); else if (smart.equals(btn2)) { try{ File myfile = new File ("C:/FinalFall13.txt"); PrintWriter pw = new PrintWriter(myFile); pw.println(message); pw.close(); JOptionPane.showMessageDialog(null, "Successfully Saved"); catch (Exception ex){ JOptionPane.showMessageDialog(null,ex.getMessage()); else if(smart.equals(btn3)) System.exit(0); Part 4 answer Q4 myframe= new Q4(); myframe.setvisible(true); End of the Questions M257 Final Exam / General MOCK Page 11