Question

Please make the following code modular. Therefore contained in a package with several classes and not just one.

import java.util.*;
public class Q {
   public static LinkedList<String> dogs = new LinkedList<String> ();
   public static LinkedList<String> cats = new LinkedList<String> ();
   public static LinkedList<String> animals = new LinkedList<String> ();
   public static void enqueueCats(){
       System.out.println("Enter name");
       Scanner sc=new Scanner(System.in);
       String name = sc.next();
       cats.addLast(name);
       animals.addLast(name);
   }
   public static void enqueueDogs(){
       System.out.println("Enter name");
       Scanner sc=new Scanner(System.in);
       String name = sc.next();
       dogs.addLast(name);
       animals.addLast(name);
   }
   public static void removeFromQueue(char q,String name){
       LinkedList<String> L = new LinkedList<String> ();
       switch (q) {
           case 'c':
               L = cats;
               break;
           case 'd':
               L = dogs;
               break;
           case 'a':
               L = animals;
       }
      
       LinkedList<String> tmp = new LinkedList<String> ();
       while (!L.isEmpty()){
           if(!L.getFirst().equals(name)){
               tmp.add(L.getFirst());
           }
           L.removeFirst();
       }
       while (!tmp.isEmpty()){
           L.add(tmp.removeLast());
       }
   }
   public static void dequeueCats(){
       System.out.println("Enter name");
       Scanner sc=new Scanner(System.in);
       String name = sc.next();
       removeFromQueue('c',name);
       removeFromQueue('a',name);
   }
   public static void dequeueDogs(){
       System.out.println("Enter name");
       Scanner sc=new Scanner(System.in);
       String name = sc.next();
       removeFromQueue('d',name);
       removeFromQueue('a',name);
   }

   public static void dequeueAnimals(){
       System.out.println("Enter name");
       Scanner sc=new Scanner(System.in);
       String name = sc.next();
       removeFromQueue('a',name);
       removeFromQueue('d',name);
       removeFromQueue('c',name);
   }
   public static void display(){
       System.out.println("animals:");
       for (String s : animals)
            System.out.print(s);
        System.out.println();
        System.out.println("cats:");
       for (String s : cats)
            System.out.print(s);
        System.out.println();
        System.out.println("dogs:");
       for (String s : dogs)
            System.out.print(s);
        System.out.println();
   }

   public static void display_choices(){
       String [] choices = {"Donate a Cat","Donate a Dog","Adopt a Cat","Adopt a Dog","Adopt Oldest Pet","Exit"};
       for (int i=0;i<choices.length ;i++ ) {
           System.out.println((i+1)+"."+choices[i]);
       }
   }
   public static void main(String[] args) {
       Scanner sc=new Scanner(System.in);
       while(true){
           display_choices();
           int choice=sc.nextInt();
           switch (choice) {
               case 1 :
                   enqueueCats();
                   display();
                   break;
               case 2 :
                   enqueueDogs();
                   display();
                   break;
               case 3 :
                   dequeueCats();
                   display();
                   break;
               case 4 :
                   dequeueDogs();
                   display();
                   break;
               case 5:
                   dequeueAnimals();
                   display();
               case 6 :
                   System.exit(0);
           }
       }
   }
  
}

Answer 1

JAVA PROGRAM

=========================

TheQueue class

=========================

package test.queue;

import java.util.LinkedList;

//Parent class : TheQueue
public class TheQueue {
  
   protected LinkedList<String> theList; //protected : will be accessible to child classes
  
   //constructor
   public TheQueue(LinkedList<String> linkList){
       this.theList = linkList;
   }
  
  
   //remove From Queue logic
   //The String with name will be removed from linkedlist
   private void removeFromQueue(String name){
   LinkedList<String> tmp = new LinkedList<String> ();
while (!theList.isEmpty()){
if(!theList.getFirst().equals(name)){
tmp.add(theList.getFirst());
}
theList.removeFirst();
}
while (!tmp.isEmpty()){
   theList.add(tmp.removeLast());
}
   }
  
   //ennque: name will be added
   public void enqueue(String name){
       theList.add(name);
   }
  
   //dequeue: removeFromQueue () will be called
   public void dequeue(String name){
       removeFromQueue(name);
   }
  
}

====================================

CatQueue class

====================================

package test.queue;

import java.util.LinkedList;

//Child class
public class CatQueue extends TheQueue{
   private static LinkedList<String> cats = new LinkedList<String>();//static linked list created
   public CatQueue() {
       super(cats);//passed to superclass constructor
   }

}

=====================================

DogQueue class

=====================================

package test.queue;

import java.util.LinkedList;

//Child class
public class DogQueue extends TheQueue{
   private static LinkedList<String> dogs = new LinkedList<String>();//static linked list created
   public DogQueue() {
       super(dogs);//passed to superclass constructor
   }

}

==========================================

AnimalQueue class

==========================================

package test.queue;

import java.util.LinkedList;

//Child class
public class AnimalQueue extends TheQueue{
   private static LinkedList<String> animals = new LinkedList<String>();//static linked list created
   public AnimalQueue() {
       super(animals);//passed to superclass constructor
   }

}

===============================

Q class (the main program)

===============================

package test.queue;

import java.util.*;

//The main class: Q
public class Q {

//create 3 static queues
private static CatQueue cq = new CatQueue();
private static DogQueue dq = new DogQueue();
private static AnimalQueue aq = new AnimalQueue();

//this method will take the name from user
private static String getName(Scanner sc){
   System.out.println("Enter name");
String name = sc.next();
return name;
}

//this method will enqueue the cat in cat queue as well as animal queue
private static void enqueueCats(Scanner sc){
   String name = getName(sc);
cq.enqueue(name);
aq.enqueue(name);
}

//this method will enqueue the dog in dog queue as well as animal queue
public static void enqueueDogs(Scanner sc){
   String name = getName(sc);
dq.enqueue(name);
aq.enqueue(name);
}
//this method will dequeue the cat from cat queue as well as animal queue
public static void dequeueCats(Scanner sc){
   String name = getName(sc);
cq.dequeue(name);
aq.dequeue(name);
}

//this method will dequeue the dog from dog queue as well as animal queue
public static void dequeueDogs(Scanner sc){
   String name = getName(sc);
dq.dequeue(name);
aq.dequeue(name);
}

//this method will dequeue the animal from animal queue as well as cat/dog queue
public static void dequeueAnimals(Scanner sc){
   String name = getName(sc);
aq.dequeue(name);
cq.dequeue(name);
dq.dequeue(name);
}

//display the animals, cats, dogs
public static void display(){
System.out.println("animals:");
for (String s : aq.theList)
System.out.print(s+" ");

System.out.println();
System.out.println("cats:");
  
for (String s : cq.theList)
System.out.print(s+" ");

System.out.println();
System.out.println("dogs:");
  
for (String s : dq.theList)
System.out.print(s+" ");

System.out.println();
}

//display choices
public static void display_choices(){
String [] choices = {"Donate a Cat","Donate a Dog","Adopt a Cat","Adopt a Dog","Adopt Oldest Pet","Exit"};
for (int i=0;i<choices.length ;i++ ) {
System.out.println((i+1)+"."+choices[i]);
}
}

//main method
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
while(true){
display_choices();
int choice=sc.nextInt();
switch (choice) {
case 1 :
enqueueCats(sc);
display();
break;
case 2 :
enqueueDogs(sc);
display();
break;
case 3 :
dequeueCats(sc);
display();
break;
case 4 :
dequeueDogs(sc);
display();
break;
case 5:
dequeueAnimals(sc);
display();
break;
case 6 :
System.exit(0);
}
}
}
  
}

==========================================

OUTPUT

==========================================

1.Donate a Cat
2.Donate a Dog
3.Adopt a Cat
4.Adopt a Dog
5.Adopt Oldest Pet
6.Exit
1
Enter name
whitecat
animals:
whitecat
cats:
whitecat
dogs:

1.Donate a Cat
2.Donate a Dog
3.Adopt a Cat
4.Adopt a Dog
5.Adopt Oldest Pet
6.Exit
1
Enter name
bluecat
animals:
whitecat bluecat
cats:
whitecat bluecat
dogs:

1.Donate a Cat
2.Donate a Dog
3.Adopt a Cat
4.Adopt a Dog
5.Adopt Oldest Pet
6.Exit
2
Enter name
husky
animals:
whitecat bluecat husky
cats:
whitecat bluecat
dogs:
husky
1.Donate a Cat
2.Donate a Dog
3.Adopt a Cat
4.Adopt a Dog
5.Adopt Oldest Pet
6.Exit
2
Enter name
pitbull
animals:
whitecat bluecat husky pitbull
cats:
whitecat bluecat
dogs:
husky pitbull
1.Donate a Cat
2.Donate a Dog
3.Adopt a Cat
4.Adopt a Dog
5.Adopt Oldest Pet
6.Exit
1
Enter name
redcat
animals:
whitecat bluecat husky pitbull redcat
cats:
whitecat bluecat redcat
dogs:
husky pitbull
1.Donate a Cat
2.Donate a Dog
3.Adopt a Cat
4.Adopt a Dog
5.Adopt Oldest Pet
6.Exit
2
Enter name
dalmetian
animals:
whitecat bluecat husky pitbull redcat dalmetian
cats:
whitecat bluecat redcat
dogs:
husky pitbull dalmetian
1.Donate a Cat
2.Donate a Dog
3.Adopt a Cat
4.Adopt a Dog
5.Adopt Oldest Pet
6.Exit
3
Enter name
redcat
animals:
dalmetian pitbull husky bluecat whitecat
cats:
bluecat whitecat
dogs:
husky pitbull dalmetian
1.Donate a Cat
2.Donate a Dog
3.Adopt a Cat
4.Adopt a Dog
5.Adopt Oldest Pet
6.Exit
4
Enter name
pitbull
animals:
whitecat bluecat husky dalmetian
cats:
bluecat whitecat
dogs:
dalmetian husky
1.Donate a Cat
2.Donate a Dog
3.Adopt a Cat
4.Adopt a Dog
5.Adopt Oldest Pet
6.Exit
5
Enter name
husky
animals:
dalmetian bluecat whitecat
cats:
whitecat bluecat
dogs:
dalmetian
1.Donate a Cat
2.Donate a Dog
3.Adopt a Cat
4.Adopt a Dog
5.Adopt Oldest Pet
6.Exit
6