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5. list visitor examples

Singleton constructor for list algorithm
/** * Computes the length of the IList host.*/ public class GetLength implements IListAlgo {/** * Singleton Pattern.*/ public static final GetLength Singleton = new GetLength();private GetLength() { }
Empty and non-empty cases of algorithm
/*** Returns Integer(0). * @param nu not used* @return Integer(0) */public Object emptyCase( MTList host, Object... nu) {return 0; } /*** Return the length of the host's rest * plus 1.* @param nu not used. * @return Integer>0. */public Object nonEmptyCase( NEList host, Object... nu) {Object restLen = host.getRest().execute(this);return 1 + (Integer)restLen); }
Singleton constructor for list algorithm
package listFW;/** * Computes a String reprsentation of IList showing a left parenthesis followed* by elements of the IList separated by commas, ending with with a right parenthesis. */public class ToStringAlgo implements IListAlgo { public static final ToStringAlgo Singleton = new ToStringAlgo();private ToStringAlgo() { }
Empty and non-empty cases of algorithm
/*** Returns "()". */public Object emptyCase( MTList host, Object... inp) {return "()"; } /*** Passes "(" + first to the rest of IList* and asks for help to complete the * computation.*/ public Object nonEmptyCase(NEList host, Object...  inp) { return host.getRest().execute(ToStringHelper.Singleton, "(" + host.getFirst());} } //closing parenthesis for the class


Singleton constructor for helper visitor
/** * Helps ToStringAlgo compute the String representation of the rest of the list.*/ class ToStringHelper implements IListAlgo {public static final ToStringHelper Singleton = new ToStringHelper(); private ToStringHelper() { }
Empty and non-empty cases of algorithm
/** * Returns the accumulated String + ")".* At end of list: done! */public Object emptyCase( MTList host, Object... acc) {return  acc[0] + ")";} /** * Continues accumulating the String* representation by appending ", " + first * to acc and recurse!*/ public Object nonEmptyCase(NEList host, Object... acc) { return host.getRest().execute(this, acc[0]+ ", " + host.getFirst()); }}

We now can use to ToStringAlgo to implement the toString() method of an IList.

package listFW;public class MTList implements IList { /*** Singleton Pattern */public final static MTList Singleton = new MTList();private MTList() { } /*** Calls the empty case of the * algorithm algo, passing to it* itself as the host parameter * and the given input inp as the* input parameter. * This method is marked as final* to prevent all subclasses from * overriding it. Finalizing a* method also allows the compiler * to generate more efficient* calling code. */public final Object execute( IListAlgo algo,Object... inp) { return algo.emptyCase(this, inp); }public String toString() { return (String)ToStringAlgo.Singleton.emptyCase(this); }} package listFW;public class NEList implements IList { /*** The first data element. */private Object _first; /*** The rest or "tail" of this NEList. * Data Invariant: _rest != null;*/ private IList _rest;/** * Initializes this NEList to a given* first and a given rest. * @param f This NEList's first element* @param r !=null; rest of this NEList. */public NEList(Object f, IList r) { _first = f;_rest = r; }/** * Returns the first data element of* this NEList. * Marked final for the above reasons.*/ public final Object getFirst() {return _first; }/** * Returns the rest of this NEList which* is an IList. * Marked final for the above reasons.*/ public final IList getRest() {return _rest; }/** * Calls the nonEmptyCase method of the* IListAlgo parameter, passing itself * as the host parameter and the given* input as the input parameter. * Marked final for the above reasons.*/ public final Object execute(IListAlgo algo, Object... inp) { return algo.nonEmptyCase(this, inp);} public String toString() {return (String)ToStringAlgo .Singleton.nonEmptyCase(this);} }

Download the above code here .

Questions & Answers

so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Principles of object-oriented programming. OpenStax CNX. May 10, 2013 Download for free at http://legacy.cnx.org/content/col10213/1.37
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