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F?ZZZZ??????F?ZZZZ?????? ???????????QQG????QQ????????^???K-adobe-courier ZZ????F ZZ?\???K Courier New ZZK ZZK Courier New ZZK-adobe-courier ZZ????**????????G????F ZZ????K Courier New ??????K ZZ????$$K Courier New ZZF ZZ????????""??""F@\??????F?\??????F?\???F???????F????F?\???22F?]??????F?33@\??????F????K????<$K?\???K????<$K?\????\K?\??????F????""F?\???""K????F?]???@F?]??????????????? ???? ????????""????""????"" ????"" ???? ??<????-????3????<?-?3??\]???syntax-coloring:Java:keyword?\]????\]???dsyntax-coloring:Java:string?\]???dsyntax-coloring:Java:literal?\]???d?\]???iiisyntax-coloring:Java:comment?\]???iii?\]???@syntax-coloring:Java:error?\]???@?\]??? syntax-coloring:Java:identifier?\]????\]???syntax-coloring:Java:default?\]??? ???? ?F ZZK Courier NewZZ//////////////////////////////////////////////////////////////// // File lab6.java  // B------------------------------------------------------------------ // interface to represent a method from object to boolean interface IObj2Bool{   boolean select(Object obj); }  // B------------------------------------------------------------------ //  Functional (External) Iterator Pattern   interface IRange {   // move the cursor one forward, assuming it is not empty   void next();     // select the item to which the cursor points, assuming it is not empty  Object current();     // test whether there are more items in the range   boolean hasMore();  }  // B------------------------------------------------------------------ // classes to represent an arbitrary list of objects abstract class ALoObj{ }  class MTLoObj extends ALoObj{   MTLoObj() {} }  class ConsLoObj extends ALoObj{   Object first;   ALoObj rest;    ConsLoObj(Object first, ALoObj rest){     this.first = first;     this.rest = rest;   } }  // B------------------------------------------------------------------ //  Functional (External) Iterator Pattern: / / iterator for a list of objects   class  ListRange  implements IRange {   //9 --------------------------------------------------------   // Member data  ALoObj ptr; /* reference to this list */    /:/--------------------------------------------------------   // Constructor   ListRange(ALoObj aList) { this.ptr = aList; }    /9/--------------------------------------------------------  // Methods to  implement the IRange  interface  void next() {  this.ptr = ((ConsLoObj)this.ptr).rest;   }   Object current() {  return ((ConsLoObj)this.ptr).first;   }    boolean hasMore() {  return (this.ptr  instanceof ConsLoObj);   } }  // B------------------------------------------------------------------ // objects to keep in the list class Book {   String title;  String author;   int price;   Book(String title, String author, int price) {    this.title = title;     this.author = author;    this.price = price;   }  }   // B------------------------------------------------------------------ // the client class that uses the list of objects, the iterator, and the IObj2Bool interface class TestClass{    TestClass(){}    // externally defined recursive filter    ALoObj filter(IRange it, IObj2Bool io2b){   // not empty?    if (it.hasMore()){    // remember local value and advance the iterator    Object obj = it.current();    it.next();     // select this item?, add it and go on      if (io2b.select(obj))      return new ConsLoObj(obj, filter(it, io2b));        // not selected, go on       else         return filter(it, io2b);     }     // empty clause     else       return new MTLoObj();   }    // external iterative filter   ALoObj iterFilter(IRange it, IObj2Bool io2b){          // empty clause     ALoObj result = new MTLoObj();      // traverse the list     for (IRange r = it; r.hasMore(); r.next()){       if (io2b.select(r.current()))         result = new ConsLoObj(r.current(), result);     }      // return the result - note that it is in reverse order     return result;   }  }  // book selector by price: cheaper than given price class BookCheaperThan implements IObj2Bool{   int price;    BookCheaperThan(int price){     this.price = price;   }      // select Book object with cheaper price that this.price  boolean select(Object obj){    return (((Book)obj).price) < this.price;   } }  3 Book b1 = new Book("1", "2", 34);  Book b2 = new Book("3", "4", 32);  Book b3 = new Book("HtDP", "mf", 60);  ALoObj mt = new MTLoObj();  ALoObj list1 = new ConsLoObj(b1, mt);  ALoObj list2 = new ConsLoObj(b2, new  ConsLoObj(b3, list1));  TestClass test = new  TestClass();  test.filter(new  ListRange(list2), new BookCheaperThan(35));  test.filter(new  ListRange(list1), new BookCheaperThan(30));  test. iterFilter(new  ListRange(list2), new BookCheaperThan(35));  test.iterFilter(new  ListRange(list1), new BookCheaperThan(30));     u Standard?????????????? filter testtest.filter(new  ListRange(list2), new BookCheaperThan( 35)) ;$new ConsLoObj(b2, new ConsLoObj(b1, mt))  Standard?????????????? filter testtest.filter(new  ListRange(list1), new BookCheaperThan( 30)) ;mt    Standard??????????????F ZZ filter testtest.iterFilter(new  ListRange(list2), new BookCheaperThan( 35)) ;$new ConsLoObj(b1, new ConsLoObj(b2, mt))  Standard??????????????F ZZ filter testtest.iterFilter(new  ListRange(list1), new BookCheaperThan( 30)) ;mt