Module Contact: Dr Geoff McKeown, CMP Copyright of the University of East Anglia Version 2

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1 UNIVERSITY OF EAST ANGLIA School of Computing Sciences Main Series UG Examination PROGRAMMING 1 CMPC1M0Y Time allowed: 2 hours Section A (Attempt all questions: 80 marks) Section B (Attempt one question: 40 marks) Notes are not permitted in this examination. Do not turn over until you are told to do so by the Invigilator. CMPC1M0Y Module Contact: Dr Geoff McKeown, CMP Copyright of the University of East Anglia Version 2

2 Page 2 1. (a) In the context of Java: SECTION A (i) distinguish between a class and an object; (ii) give the structure of a class defining a new type of object; (b) explain the differences between primitive data types and reference types; (c) Explain what is meant by a static method in Java. Give Java code for a static method called weightconverter that takes a double representing a weight in pounds and returns a double representing the equivalent weight in kilograms. [Take one pound to be kg.] [8 marks] 2. (a) Give Java code to define an array, marks, of doubles with length n. [2 marks] (b) Assuming values representing the marks for a course test have been assigned to the elements of marks, give Java code to determine the number of pass marks (assume that the minimum mark for a pass is 40). (c) In the context of Java methods, distinguish between formal parameters and actual parameters. Describe what happens when a method is invoked in Java. [8 marks] (d) A static method, sieve, has two formal parameters. The first parameter is an array of Strings each of whose elements represents a word in English. The second formal parameter is a character corresponding to a letter in the English alphabet. The method is to return an array of Strings whose elements represent those words in the given array that begin with the given letter. (i) Write Java code for the header of sieve. [Note: You are NOT required to write the body for this method.] (ii) Suppose names is an array of student names. Give Java code that uses sieve to determine the array of student names CMPC1M0Y Version 2

3 Page 3 beginning with the letter A. [Assume that no name contains any characters other than letters.] 3. (a) Distinguish between accessor methods and mutator methods in a Java class. (b) An electronics company needs to implement a simple stock control system. For each type of item, the following data is held: inventory identifier (e.g. A654Y); quantity in stock (e.g. 350); demand rate (quantity removed from stock each working day, assumed constant, e.g. 50); re-order quantity (the size of an ordered batch of items, assumed constant, e.g 1000); lead-time (number of working days delay between placing and receiving an order for a batch, e.g. 5). Operations that need to be implemented for a type of stock item include the following: a constructor with arguments for all fields; an accessor method for the re-order quantity; a method to update the stock quantity when a batch is received; a method isreorderpoint( ) that returns true if a batch needs to be re-ordered for this stock item and false otherwise; a tostring method that returns a description of the stock item Write a definition for a class StockItem containing the methods described above. [16 marks] CMPC1M0Y Version 2 TURN OVER

4 Page 4 4. (a) In the context of Java, what does recursion mean? [2 marks] (b) When defining a recursive solution, what rules must you adhere to? (c) What is a tail recursion? [2 marks] (d) The static method iterativesum returns the sum of the first n terms of an array. Write a recursive static method called recursivesum to perform the same task. [9 marks] public static int iterativesum(int[] A, int n){ int sum=0; for(int i=0;i<n;i++) sum=sum+a[i]; return sum; } (e) Which is the better solution, iterativesum or recursivesum? Justify your answer. CMPC1M0Y Version 2

5 Page 5 SECTION B 5. (a) Let Film be a class which has a constructor with header public Film(String title) Write Java code to do each of the following: (i) Define an array variable filmcollection that could be used to refer to an array of n Film objects, where n is an int variable to which a positive value has been assigned; (ii) create a new Film object for a film with title The Big Lebowski using the above constructor and assign this to the last element in filmcollection; (iii) delete the Film in location i of filmcollection (assume 0 <= i <= n); (iv) create an ArrayList of Film objects; (v) create a new Film object for a film with title The Reader using the above constructor and add this Film to your ArrayList. (b) Define what is meant by an algorithm. (c) Describe the linear search algorithm for searching for a given item in an unsorted array of Comparable objects. [10 marks] CMPC1M0Y Version 2 TURN OVER

6 Page 6 6. (a) In the context of Java, what does inheritance mean? (b) Given the following class public class Person{ protected String name; protected int age; } write a class Student that inherits from Person, has an extra field for the student ID number and a method that sets the ID. (c) Describe the relationship between Person and Student in a UML class diagram. (d) Suppose a class called Module contains a public collection of objects of type Student called classlist, a further private String field called name and a constructor that takes the number of students and the module name as arguments. Represent this relationship as a UML class diagram, then implement the class Module. [8 marks] (e) Explain with the aid of examples what is meant by the following terms used in relation to inheritance: (i) polymorphism; (ii) abstract methods and classes; (iii) interfaces; (iv) casting. END OF PAPER CMPC1M0Y Version 2