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This homework on manipulating Java lists must be done using the Intermediate language level of DrJava. We are providing skeleton classes for each problem with unimplemented methods for you to write. Each such class includes a method with a name like listString()
that converts lists to more readable String notation similar to that used in Scheme.
arrangements
(permutations) function from HTDP problem 12.4.2 in HW2 as a Java method for a Word
class provided in the file Word.dj1
. This file includes definitions of the composite pattern classes Word
and WordList
. Decompose the problem in exactly the same form as this solution to problem 12.4.2. We are providing skeletons for the classes Word
and WordList
in the file WordList.dj1; use them.mergesort
function from the last problem in HW4 (using exactly the same top-down approach described in HW4) as a Java method in the composite pattern class ComparableList
provided in the file ComparableList.dj1.ObjectList
provided in the file ObjectList.dj1. This file includes the interface Predicate
, which is the type of Java function arguments passed to the filter
method, and abstract method stubs for filter
, eliminateExp
, recall
, and selection
. Exercise 21.2.3 provides Scheme code for the filter
function which you should directly translate to the corresponding Java method code in ObjectList
. Note that your filter
method should work for arbitrary ObjectLists
. In coding the methods eliminateExp
, recall
, and selection
, use the Java type Number
(compared using method doubleValue
in place of the Scheme number
type and the Java type Object
in place of the Scheme symbol
type. The method doubleValue()
in Number
returns the value of this converted to a double
. You will need to cast the Object
input of the test
method to type Number
when filtering lists of numbers.