CS2110 Spring 2014 Assignment A1. Fibonacci Bees Due on CMS by Friday 7 Feb, 11:59PM. CS1110 Spring 2010 Assignment A1 Fibonacci Bees

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1 1 CS1110 Spring 2010 Assignment A1 Fibnacci Bees Intrductin Bees have a funny way f prpagating. An unfertilized female bee, the queen bee, will have male ffspring. But the ffspring f a fertilized female will be females. Yu can see what happens in the tree t the right. The male n level 1 has ne parent, a female, n level 2. That parent has tw parents, as shwn n level 3, and thse tw bees n level 2 have a ttal f three parents, as shwn n level 4, etc. Yu can see that the number f ancestrs n increasing levels frms the sequence 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, This is the Fibnacci sequence: f(0)= 0, f(1)= 1, and fr n > 1, f(n) = f(n-1) + f(n-2). Isn t that neat? The image f a bee abve is frm the website Yu can find many stunning, up-clse images f bees there. In this assignment, we assume we can mnitr bees. Yur task will be t develp a Java class Bee t maintain infrmatin abut them and a testing class BeeTester t maintain a suite f test-cases fr Bee. This assignment illustrates hw Java's classes and bjects can be used t maintain data abut a cllectin f things like entities in a large tracking system. Learning bjectives Gain familiarity with Java and Eclipse and the structure f a basic class within a recrd-keeping scenari (a cmmn type f applicatin). Learn abut and practice reading carefully. Wrk with examples f gd Javadc specificatins t serve as mdels fr yur later cde. Learn the cde presentatin cnventins fr this curse (Javadc specificatins, indentatin, shrt lines, etc.), which help make yur prgrams readable and understandable. Learn and practice incremental cding, a sund prgramming methdlgy that interleaves cding and testing. Learn abut and practice thrugh testing f a prgram using JUnit testing. Learn t write class invariants. Learn abut precnditins f a methd (requirements f a call n the methd that need nt be tested) and the use f the Java assert statement fr checking precnditins. The methds we ask yu t write in this assignment are shrt and simple; the emphasis is n "gd practices", nt cmplicated cmputatins. Reading carefully At the end f this dcument is a checklist f items fr yu t cnsider befre submitting A1, shwing hw many pints each item is wrth. Check each ne carefully. A lw grade is almst always due t lack f attentin t detail and t nt fllwing instructins nt t difficulty understanding OO. At this pint, we ask yu t visit the webpage n the website f Fernand Pereira, research directr fr Ggle: Did yu read that webpage carefully? If nt, read it nw! The best thing yu can d fr yurself and us at this pint is t read carefully. This handut cntains many details. Yu have t read carefully t get this assignment right. Save yurself and us a lt f anguish by ding that as yu d this assignment.

2 2 Cllabratin plicy Yu may d this assignment with ne ther persn. If yu are ging t wrk tgether, then, as sn as pssible and certainly befre yu submit the assignment get n the CMS fr the curse and d what is required t frm a grup. Bth peple must d smething befre the grup is frmed: ne prpses, the ther accepts. If yu need help with the CMS, visit If yu d this assignment with anther persn, yu must wrk tgether. It is against the rules fr ne persn t d sme prgramming n this assignment withut the ther persn sitting nearby and helping. Yu shuld take turns "driving" using the keybard and muse. With the exceptin f yur CMS-registered partner, yu may nt lk at anyne else's cde, in any frm, r shw yur cde t anyne else, in any frm. Yu may nt shw r give yur cde t anther persn in the class. Getting help If yu dn't knw where t start, if yu dn't understand testing, if yu are lst, etc., please SEE SOMEONE IMMEDIATELY a curse instructr, a TA, a cnsultant. Or, ask a questin and lk fr answers n the curse Piazza. D nt wait. A little in-persn help can d wnders. See the curse hmepage fr cntact infrmatin. Using the Java assert statement t test precnditins As yu knw, a precnditin is a cnstraint n the parameters f a methd, and it is up t the user t ensure that methd calls satisfy the precnditin. If a call des nt, the methd can d whatever it wants. Hwever, especially during testing and debugging, it is useful t use Java assert statements at the beginning f a methd t check that the precnditin is true. Fr example, if the precnditin is : this bee s mther is unknwn and e is female., ne can use an assert statement like the fllwing (using bvius names fr fields): assert mm == null && e!= null && e.gender == 'F'; The additinal test e!= null is there t prtect against a null-pinter exceptin, which will happen if the argument crrespnding t e in the call is null. [This is imprtant!] In this assignment, all precnditins f methds must be checked using assert statements at the beginning f the methd. Write the assert statements as the first step in writing the methd bdy, s that they are always there during testing and debugging. Als, when yu generate a new JUnit class, make sure the VM argument -ea is present in the Run Cnfiguratin. Yu will find these assert statements helpful in testing and debugging. Hw t d this assignment Scan the whle assignment befre starting. Then, develp class Bee and test it using class BeeTester in the fllwing incremental, sund way. This will help yu cmplete this (and ther) prgramming tasks quickly and efficiently. If we detect that yu did nt develp it this way, pints will be deducted. 1. In Eclipse, create a new prject, called a1bee. In a1bee, create a new class, called Bee. It shuld nt be in a package, and it des nt need a methd main (but yu may add ne if yu want). As the first line f file Bee.java, put this: /** An instance (i.e. bject) maintains infrmatin abut a bee. */ Remve the cnstructr with n parameters, since it will nt be used and its use can leave an bject in an incnsistent state (see belw, the class invariant). 2. In class Bee, declare the fllwing fields (yu chse the names f the fields), which are meant t hld infrmatin describing a bee. Make these fields private and prperly cmment them (see the "The class invariant" sectin belw).

3 3 Nte: yu must break lng lines (including cmments) int tw r mre lines s that the reader des nt have t scrll right t read them. This makes yur cde much easier fr us and yu t read. A gd guideline: N line is mre than 80 characters lng. nickname (a String). Name given t this Bee, a String f length > 0. year f hatching (an int). Must be >= mnth f hatching (an int). In range with 1 being January, etc. gender f this Bee (a char). M means male and F means female. If the bee is male, it has n father. mther (a Bee). (Name f) the bject f class Bee that is the mther f this bject null if unknwn father (a Bee). (Name f) the bject f class Bee that is the father f this bject null if unknwn r this bee is male. number f children f this Bee. Nte the fllwing abut the field that cntains the number f children. The user never gives a value fr this field; it is cmpletely under cntrl f the prgram. Fr example, if a Bee b is given a mther m, then m s number f children must be increased by 1. It is up t the prgram, nt the user, t increase the field. The class invariant. Recall that cmments shuld accmpany the declaratins f all fields t describe what each field means, what cnstraints hld n the fields, and what the legal values are fr the fields. Fr example, fr the year-f-hatching field, state in a cmment that the field cntains the year f hatching and that it must be >= The cllectin f the cmments n these fields is called the class invariant. Here is an example f a declaratin with a suitable cmment. Nte that the cmment des nt give the type (since it is bvius frm the declaratin), it des nt use nise phrases like this field cntains, and it des cntain cnstraints n the field. char hatchyear; // year f hatching f this Bee. >= 2000 Nte again that we did nt put (a char) in the cmment. That infrmatin is already knwn frm the declaratin. Dn t put such unnecessary things in the cmments. Whenever yu write a methd (see belw), lk thrugh the class invariant and cnvince yurself that the class invariant still hlds when the methd terminates. This habit will help yu prevent r catch bugs later n. 3. In Eclipse, start a new JUnit test class and call it BeeTester. Yu can d this using men item File > New > JUnit Test Case. 4. Belw, fur grups A, B, C, and D f methds are described. Wrk with ne grup at a time, perfrming steps (1)..(4). D nt g n t the next grup f methds until the grup yu are wrking n is thrughly tested and crrect. (1) Write the Javadc specificatins fr each methd in that part. Make sure they are cmplete and crrect lk at the specificatins we give yu belw. Cpy-and-paste frm this handut makes this easy. (2) Write the methd bdies, starting with assert statements fr the precnditins. (3) Write ne test prcedure fr this grup in class BeeTester and add test cases t it fr all the methds in the grup. (4) Test the methds in the grup thrughly. Discussin f the grups f methds. The descriptins belw represent the level f cmpleteness and precisin we are lking fr in yur Javadc specifeicatin-cmments. In fact, yu may (shuld) cpy and paste these descriptins t create the first draft f yur Javadc cmments. If yu d nt cut and paste, adhere t the cnventins we use, such as using the prefix "Cnstructr: " and duble-qutes t enclse an English blean assertin. Using a cnsistent set f gd cnventins in this class will help us all.

4 4 Methd specificatins d nt mentin fields because the user may nt knw what the fields are, r even if there are fields. The fields are private. Cnsider class JFrame: yu knw what methds it has but nt what fields, and the methd specificatins d nt mentin fields. In the same way, a user f yur class Bee will knw the methds but nt the fields. The names f yur methds must match thse listed belw exactly, including capitalizatin. The number f parameters and their rder must als match: any mismatch will cause ur testing prgrams t fail and will result in lss f pints fr crrectness. Parameter names will nt be tested change the parameter names if yu want. In this assignment, yu may nt use if-statements, cnditinal expressins, r lps. Grup A: The first cnstructr and the getter methds f class Bee. Cnstructr Bee(String n, char g, int y, int m) Cnstructr: an instance with nickname n, gender g, birth year y, and birth mnth m. Its parents are unknwn, and it has n children. Precnditin: n has at least 1 character, y >= 2000, m is in 1..12, and g is 'M' fr male r 'F' fr female. Getter Methd Return Type getnickname() Return this Bee's nickname String getyear() Return the year this Bee hatched frm its egg int getmnth() Return the mnth this Bee hatched frm its egg int ismale() Return the value f "This Bee is male. blean getmm() Return this Bee's mther (null if unknwn) Bee (nt String!) getdad() Return this Bee's father (null if unknwn) Bee (nt String!) getnumchildren() Return the number f children f this Bee int Cnsider testing the cnstructr. Based n the specificatin f the cnstructr, figure ut what value it shuld place in each f the 7 fields t make the class invariant true. Then, write a prcedure named testcnstructr1 in BeeTester t make sure that the cnstructr fills in ALL fields crrectly. The prcedure shuld: Create ne Bee bject using the cnstructr and then check, using the getter methds, that all fields have the crrect values. Since there are 7 fields, there shuld be 7 assertequals statements. As a by-prduct, all getter methds are als tested. We d advise creating a secnd Bee (in testcnstructr1) f the ther sex than the ne first created and testing using functin ismale() that its sex was prperly stred. Grup B: the setter r mutatr methds. Nte that methds addmm and adddad may have t change fields f bth this Bee and the parent in rder t maintain the class invariant the parent s number f children changes! When testing the setter methds, yu will have t create ne r mre Bee bjects, call the setter methds, and then use the getter methds t test whether the setter methds set the fields crrectly. Gd thing yu already tested the getters! Nte that these setter methds may change mre than ne field; yur testing prcedure shuld check that all fields that may be changed are changed crrectly. We are nt asking yu t write methds that change an existing father r mther t a different Bee. This wuld require if-statements, which are nt allwed. Read precnditins f methds carefully. Setter Methd addmm(bee e) Add e as this Bee's mther. Precnditin: this Bee s mther is unknwn and e is female.

5 5 Setter Methd adddad(bee e) Add e as this Bee's father. Precnditin: This Bee's father is unknwn, this Bee is female, and e is male. Grup C: Tw mre cnstructrs. The test prcedure fr grup C has t create Bees using the tw cnstructrs given belw. This will require first creating tw Bees, using the first cnstructr; then check that these tw cnstructr set all 7 fields prperly.! Cnstructrs Bee(String n, int y, int m, Bee ma) Cnstructr: a male Bee with nickname n, hatch year y, hatch mnth m, and mther ma. Precnditin: n has at least 1 character, y >= 2000, m is in 1..12, and ma is a female. Bee(String n, int y, int m, Bee ma, Bee pa) Cnstructr: a female Bee with nickname n, hatch year y, hatch mnth m, mther ma, and father pa. Precnditin: n has at least 1 character, y >= 2000, m is in 1..12, ma is a female, and pa is a male. Grup D: Write tw cmparisn methds t see which f tw bees is yunger and t see whether tw bees are siblings (i.e. they are nt the same bject and they have a nn-null mther r a nn-null father in cmmn). Write these using nly blean expressins (with!, &&, and and relatins <, <=, ==, etc.). D nt use if-statements, switches, additin, multiplicatin, etc. Each can be written as a single return statement. Cmparisn Methd Return type isyunger(bee e) issibling(bee e) Return value f "this Bee is yunger than e. Precnditin: e is nt null. Return value f "this Bee and e are siblings. (nte: if e is null they can't be siblings, s false shuld be returned). blean blean 5. In Eclipse, click men item Prject -> Generate Javadc. In the windw that pens, make sure yu are generating Javadc fr prject, a1bee, using visibility public, and string it in a1bee/dc. Then pen dc/index.html. Yu shuld see yur methd and class specificatins. Read thrugh them frm the perspective f smene wh has nt read yur cde. Fix the cmments in class Bee, if necessary, s that they are apprpriate t that perspective. Yu must be able t understand everything there is t knw abut writing a call n each methd frm the specificatin that yu see by clicking the Javadc buttn that is, withut knwing anything abut the private fields. Thus, the fields shuld nt be mentined. Then, and nly then, add a cmment at the tp f file Bee.java saying that yu checked the Javadc utput and it was OK. 6. Check carefully that a methd that adds a mther r father t a Bee updates the mther s r father s number f children. Fur methds d this. 7. Review the learning bjectives and reread this dcument t make sure yur cde cnfrms t ur instructins. Check each f the fllwing, ne by ne, carefully. Nte that 50 pints are given fr the items belw and 50 pints are given fr actual crrectness f methds. 5 Pints. Are all lines shrt enugh that hrizntal scrlling is nt necessary (abut 80 chars is lng enugh). D yu have a blank line befre the specificatin f each methd and n blank line after it?

6 6 10 Pints. Is yur class invariant crrect are all fields defined and all field cnstraints given? 5 Pints. Is the name f each methd and the types f its parameters exactly as stated in step 4 abve (the simplest way t d this was t cpy and paste). (Mre pints may be deducted if we have difficulty fixing yur submissin s that it cmpiles with ur grading prgram.) 10 Pints. Are all specificatins cmplete, with any necessary precnditins? Remember, we specified every methd carefully and suggested cpying ur specs and pasting them int yur cde. Are they in Javadc cmments? 5 pints. D yu have assert statements at the beginning f each methd that has a precnditin t check that precnditin? 5 Pints. Did yu check the Javadc utput and then put a cmment at the tp f class Bee? 10 Pints. Did yu write ne (and nly ne) testing methd fr each f the grups A, B, C, and D f step 4? Thus, d yu have fur (4) test prcedures? Did yu prperly test? Fr example, in testing each cnstructr, did yu make sure t test that all 7 fields have the crrect value? Fr example, testing whether ne date cmes befre anther date, when each is given by a mnth and a year, prbably requires at least 5 test cases. 8. Uplad files Bee.java and BeeTester.java n the CMS by the due date. D nt submit any files with the extensin/suffix.java~ (with the tilde) r.class. It will help t set the preferences in yur perating system s that extensins always appear.!!