WXME0106 ## wxtextwxtabwxmediawximage$(lib "comment-snip.ss" "framework")+(lib "collapsed-snipclass.ss" "framework")drscheme:sexp-snipdrscheme:syntax-snipclass%drscheme:number,(lib "number-snip.ss" "drscheme" "private")drscheme:bindings-snipclass%drscheme:lambda-snip%drscheme:define-snip%java-comment-box%java-interactions-box%"drscheme:vertical-separator-snip%wxbaddrscheme:xml-snip(lib "xml-snipclass.ss" "xml")drscheme:scheme-snip"(lib "scheme-snipclass.ss" "xml")test-case-box% text-box%wxloc0K ZZ StandardK Courier New ZZ?\???""Matching Parenthesis Style?\???""????&&(framework:syntax-coloring:scheme:symbol????&&)framework:syntax-coloring:scheme:keyword????&&????t)framework:syntax-coloring:scheme:comment????t????)&(framework:syntax-coloring:scheme:string????""*framework:syntax-coloring:scheme:constant????""????<$-framework:syntax-coloring:scheme:parenthesis????<$????@'framework:syntax-coloring:scheme:error????@????'framework:syntax-coloring:scheme:other????????Qp1drscheme:check-syntax:lexically-bound-identifier????Qp????D*drscheme:check-syntax:imported-identifier????D%profj:syntax-coloring:scheme:keyword????????""$profj:syntax-coloring:scheme:string????""%profj:syntax-coloring:scheme:literal????""%profj:syntax-coloring:scheme:comment????t#profj:syntax-coloring:scheme:error????@(profj:syntax-coloring:scheme:identifier????&&%profj:syntax-coloring:scheme:default????F???????XMLF???????G???????????PPG????PPG????dK ZZK-adobe-courier ZZ????**????????G????K Courier New ZZ?^???????????F ZZ interface IFilter{   // method that selects objects with some property   boolean select(); }  interface IFilter2{   // method that selects objects with some property   boolean select2(Object obj); }   class CheapBook implements IFilter2{   // determine whether the given book is cheap   boolean select2(Object obj){     return ((Book)obj).price < 10;   } }   class NewAuthor implements IFilter2{   // determine whether the given book was written by contemporary author   boolean select2(Object obj){     return ( ((Book)obj).author.isContemporary() );   } }   class Book implements IFilter{   String title;   Author author;   int price;    Book(String title, Author author, int price) {     this.title = title;     this.author = author;     this.price = price;   }    boolean equals(Object obj){     return    (this.title.equals( ((Book) obj).title))            && (this.author.equals( ((Book) obj).author))             && (this.price == ((Book) obj).price);   }    boolean select(){     return this.price < 10;   } }   class Author implements IFilter{   String name;   int year;    Author(String name, int year){     this.name = name;     this.year = year;   }    boolean equals(Object obj) {     return    (this.name.equals( ((Author) obj).name ))            && (this.year == ( ((Author) obj).year ));   }    boolean select(){     return this.year > 1940;   }    // determine whetheri this is a contemporary author   boolean isContemporary(){     return this.year > 1940;   } }   abstract class ALoObj{    // count the number of items in this list   abstract int count();    // determine whether this list contains the given object   abstract boolean contains(Object obj);    // remove the first occurrence of the given object from this list   abstract ALoObj remove(Object obj);    // determine whether there is a 'selected' object in this list   abstract boolean orMap();    // determine whether there is a 'selected' object in this list   abstract boolean orMap2(IFilter2 filter); }   class MTLoObj extends ALoObj{    MTLoObj(){ }    int count(){ return 0; }    boolean contains(Object obj){ return false; }    ALoObj remove(Object obj){ return this; }    boolean orMap(){ return false; }    boolean orMap2(IFilter2 filter){ return false; }  }   class ConsLoObj extends ALoObj{   Object fst;   ALoObj rst;    ConsLoObj(Object fst, ALoObj rst){     this.fst = fst;     this.rst = rst;   }    Template: ...this.fst... ...this.rst... ...this.count()... ...this.contains(Object obj)... ...this.remove(Object obj)... ...this.rst.orMap()...    int count() {      return 1 + this.rst.count();   }    boolean contains(Object obj){     return    (this.fst.equals(obj))            || (this.rst.contains(obj));   }    ALoObj remove(Object obj){     if (this.fst.equals(obj))       return this.rst;     else       return new ConsLoObj(this.fst, this.rst.remove(obj));   }    boolean orMap(){     return    ( ((IFilter)(this.fst)).select() )            || (this.rst.orMap());   }    boolean orMap2(IFilter2 filter){     return   filter.select2(this.fst)            || (this.rst.orMap2(filter));   } }    "Examples"  Author mf = new Author( "Matthias", 1958);  Author bard = new Author( "Shakespeare", 1716);  Book b1 = new Book ("HtDP", mf, 60);  Book b2 = new Book ("LL", mf, 18);  Book b3 = new Book ("Hamlet", bard, 7);  ALoObj mtlist = new MTLoObj();   ALoObj list1 = new  ConsLoObj(b1, new  ConsLoObj(b2, mtlist));  ALoObj list2 = new  ConsLoObj(b3, list1);   /"Testing the count() method in class ListofObj"  mtlist.count() == 0  list1.count() == 2  list2.count() == 3  2"Testing the contains() method in class ListofObj"  mtlist.contains(b1) == false  list1.contains(b3) == false  list2.contains(b3) == true  list2.contains(b2) == true  0"Testing the remove() method in class ListofObj"  mtlist.remove(b1).equals(mtlist)  list1.remove(b3).count()  list2.remove(b3).count()  '"Testing select() method in class Book"  b1.select() == false  b2.select() == true  )"Testing select() method in class Author"  mf.select() == true  bard.select() == false  *"Testing orMap() method on lists of books"  mtlist.orMap() == false  list1.orMap() == false  list2.orMap() == true  CheapBook cheapFilter = new  CheapBook();  mtlist.orMap2( cheapFilter) == false  list1.orMap2( cheapFilter) == false  list2.orMap2( cheapFilter) == true  NewAuthor authorFilter = new  NewAuthor();  mtlist.orMap2( authorFilter) == false  list1.orMap2( authorFilter) == true  list2.orMap2( authorFilter) == true    GQExamples  (Author mf = new Author("Matthias" 1958); .Author bard = new Author("Shakespeare", 1716);  &Book b1 = new Book ("HtDP", mf, 2001); $Book b2 = new Book ("LL", mf, 1974); *Book b3 = new Book ("Hamlet", bard, 1736);  ALoObj mtlist = new MTLoObj();