C Sc 335 Practice Test 1 Section Leader Name 150pts. 3. List two Java structures that allow for polymorphic messages (2pts)

Transcription

1 C Sc 335 Practice Test 1 Sectin Leader Name 150pts 1. Write the crrect term, either "RESPONSIBILITIES" r "METHODS and DATA" in the blank space (2pts) At the cnceptual level, an bject is a set f At the implementatin level, an bject is a set f 2. Describe the essence f plymrphism. (3pts) 3. List tw Java structures that allw fr plymrphic messages (2pts) 4. If yu change ArrayList t LinkedList, will the fllwing cde still cmpile? true r false (2pts) List<String> list = new ArrayList<String>(); list.add("b"); list.add("a"); list.add("c"); Cllectins.shuffle(list); 5. Place an X by the name f any interfaces in the Java cllectin framewrk in the java.util package? (6pts) Cllectin ArrayList Queue Set Map SrtedArrayList 6. Which ges int the tp cmpartment (rectangle) f a class diagram f a single class? (2pts) Attributes(instance variables) Class Name Operatins (methds) 7. Can ne Java class implement mre than ne interface? yes r n (2pts) 8. What is better, high chesin r lw chesin? lw r high (2pts) 9. Will all assertins in the fllwing test methd pass? yes r n public vid testnext() { List<String> list = new ArrayList<String>(); list.add("b"); list.add("a"); Iteratr<String> itr = list.iteratr(); asserttrue(itr.hasnext()); assertequals("b", itr.next()); assertequals("a", itr.next()); asserttrue(itr.hasnext()); 10. Write the utput generated by the same cde when anumbermaybe is first "123" and then "NOgOOD" (6pts) String anumbermaybe = "123"; try { System.ut.println("--"); duble num= Duble.parseDuble(aNumberMaybe); System.ut.println(""); catch (NumberFrmatExceptin nfe) { System.ut.println("++"); String anumbermaybe = "NOgOOD"; try { System.ut.println("--"); duble num = Duble.parseDuble(aNumberMaybe); System.ut.println(""); catch (NumberFrmatExceptin nfe) { System.ut.println("++"); 1

2 11. Finish this prgram with a graphical user interface that will allws use t enter text int a field and be tld whether r nt that text represents a valid number. If the input is nt a number, put!!error in the middle. Hint use Duble.parseDuble(String) that thrws an exceptin if the argumnet isn't a valid number. (15pts) // Assume all imprts exist public class NumberFrame extends JFrame { public static vid main(string[] args) { new NumberFrame().setVisible(true); private JLabel heading = new JLabel("Enter a number belw"); private JLabel mylabel; private JTextField inputfield; // initialize the JFrame public NumberFrame() { settitle("numbers"); setsize(170, 125); setdefaultclseoperatin(exit_on_close); Cntainer cp = this.getcntentpane(); cp.setlayut(null); heading.setlcatin(0, 0); heading.setsize(140, 20); mylabel = new JLabel("Nthing yet..."); mylabel.setlcatin(30, 30); mylabel.setsize(140, 20); inputfield = new JTextField(); inputfield.setsize(170, 20); inputfield.setlcatin(0, 72); cp.add(heading); cp.add(mylabel); cp.add(inputfield); 2

3 12. In the bx, write class MyInteger s its bjects can be srted int their natural rdering with a call t java.util.cllectins.srt. Each cmparet message must return the difference in value with a negative value indicating the bject is less than the argument. Cmplete a test methd t cmpletely test the cmparet methd (12pts) public interface Cmparable<T> { public int cmparet(t ther); ////////////////////////////////// imprt static rg.junit.assert.*; imprt rg.junit.test; public class MyIntegerTest public vid testmyinteger() { 13. The UfA Bkstre has decided that there is just t much traffic in the bkstre at the beginning f each semester. In an effrt t reduce in-huse traffic, the bkstre has decided t implement an nline strefrnt where students can purchase all f their bks nline and just pick them up smetime after they ve been purchased. Yu are t d sme analysis and cme up with a mdel fr the bkstre s new nline frnt. Details: A student may remve 1 t many items frm the shelf and place them int a shpping basket A student shuld be able t remve items frm a shpping basket and place them back n the shelf A student shuld be able t purchase the items in their shpping basket T check ut, a student must give their shpping basket t the cashier (there is nly ne cashier) The cashier creates an rder that cnsists f a item, quantity, and a price based n the item s ISBN If the CatCard has enugh mney then the ttal amunt will be deducted and the items will be remved frm inventry, a claim check cnfirmatin fr the rder will be sent t the student s address If the CatCard funds are insufficient, place all back n the shelf Create a list f the five mst imprtant bjects t mdel this system alng with the majr respnsibility: (10pts) Candidate Object Majr Respnsibility 3

4 14. Draw a UML class diagram shwing all f yur candidate bjects and any relatinships between them. Shw inheritance relatinships, interface implementatin, r general assciatin such as dependency by drawing a line. Write any multiplicity adrnment yu can think f. Yu will likely have 1, and r * in a few places at least. Each classes needs the class name and at least ne apprpriate methd (n attributes needed fr a perfect scre). (12pts) 15. Given class Pint and a test driver fr class Circle and class Rectangle, implement a prperly designed inheritance hierarchy in Java (n the next page). Let Shape be the abstract class. Implement all three classes t the right f the nn-inheritance versin n the next page. Cmpletely implement all cnstructrs and all methds. Include all instance variables. The Circle and Rectangle classes must behave exactly the same with the inheritance hierarchy as withut. The assertins must pass. (20pts) imprt static rg.junit.assert.*; imprt rg.junit.test; public class ShapeTest public vid test getarea() { // 10 pixels ver, 10 pixels dwn, radius 2.0 Shape c = new Circle(10, 10, 2.0); asssertequals( , c.getarea(), 0.001); // width = 3.25, height = 5.75 Shape r = new Rectangle(40, 10, 3.25, 5.75); sssertequals( , r.getarea(), 0.001); // width = 3.25, height = 5.75 Shape r2 = new Rectangle(40, 60, 2, 3); asssertequals(6.0, r.getarea(), 0.1); 4

5 public class Pint { // Use this type private int xps; private int yps; Using gd Object-Oriented Design, cmpletely implement the hierarchy here public Pint(int x, int y) { xps = x; yps = y; public int getx() { return xps; public int gety() { return yps; public class Rectangle { private Pint upperleft; private duble width; private duble height; public Rectangle(int x, int y, duble height, duble width) { upperleft = new Pint(x, y); width = width; height = height; public int getx() { return upperleft.getx(); public int gety() { return upperleft.gety(); public duble getarea() { return width * height; public class Circle { private Pint upperleft; private duble radius; public Circle(int x, int y, duble diameter) { upperleft = new Pint(x,y); radius = diameter / 2; public int getx() { return upperleft.getx(); public int gety() { return upperleft.gety(); public duble getarea() { return Math.PI*Math.pw(radius, 2); 5

6 16. The Cmmand design pattern encapsulates the cncept f a cmmand int an bject. Yu can save it fr later executin. In the fllwing cde, six cmmands f tw different types are cnstructed and saved in a Vectr. Later n, the execute message is sent t all six Cmmand bjects. The three things that yu will be asked t write are highlighted in bldface: Cmmand, BrrwCmmand, and ReturnCmmand. // Have tw brrwers and three bks t stre in the tw Cmmand bjects Brrwer je = new Brrwer( Je ); Brrwer kim = new Brrwer( Kim ); Bk b0 = new Bk( Pascal ); Bk b1 = new Bk( Java ); Bk b2 = new Bk( c++ ); Cmmand c1 = new BrrwCmmand(je, b0); // Cnstruct a Cmmmand s Je brrws Pascal Cmmand c2 = new BrrwCmmand(je, b1); // Cnstruct a Cmmmand Je brrws Java Cmmand c3 = new BrrwCmmand(kim, b2); //... Cmmand c4thatfails = new BrrwCmmand(kim, b0); // Nthing will happen later with execute() Cmmand c5 = new ReturnCmmand(je, b0); Cmmand c6fails = new ReturnCmmand(je, b2); List cmmandlist = new Vectr(); cmmandlist.add(c1); cmmandlist.add(c2); cmmandlist.add(c3); cmmandlist.add(c4thatfails); // already ut cmmandlist.add(c5); cmmandlist.add(c6fails); // Desn't have fr(int j = 0; j < cmmandlist.size(); j++) { Cmmand ref = (Cmmand)cmmandList.get(j); ref.execute(); System.ut.println(brrwerList); System.ut.println(); Output Je has [] attempts t BORROW Pascal [Je has [Pascal], Kim has []] Je has [Pascal] attempts t BORROW Java [Je has [Pascal, Java], Kim has []] Kim has [] attempts t BORROW c++ [Je has [Pascal, Java], Kim has [c++]] Kim has [c++] attempts t BORROW Pascal [Je has [Pascal, Java], Kim has [c++]] Je has [Pascal, Java] attempts t RETURN Pascal [Je has [Java], Kim has [c++]] Je has [Java] attempts t RETURN c++ [Je has [Java], Kim has [c++]] 6

7 16a) Write interface Cmmand as if it were in its wn file 16b) Cmplete class BrrwCmmand as if it were in its wn file. The execute methd adjusts the Brrwer and the Bk if everything is all right. Hwever, if the Bk is already brrwed, execute returns false. // BrrwCmmand attaches a specific bk cpy t a specific subscriber, bth, the bk // cpy s and the subscriber s bjects are supplied by the prgrammer. public class BrrwCmmand implements Cmmand { prtected Brrwer thebrrwer; prtected Bk thebk; public BrrwCmmand(Brrwer abrrwer, Bk abk) { thebrrwer = abrrwer; thebk = abk; // When the Brrw buttn is clicked, execute this public blean execute() { System.ut.println(theBrrwer + " attempts t BORROW " + thebk); public blean und() { // a brrw by returning System.ut.println(theBrrwer + " und a Brrw" + thebk); 7