Question

The Acme Trucking company has hired you to write software to help dispatch its trucks. One important element of this software is knowing the distance between any two cities that it services. Design and implement a Distance class that stores the distances between cities in a two-dimensional array. This class contains the following required data members and methods: Required Data Members: String[] cities; //it is used to store city names int[][] distance; // this 2-D array repreents distance between two cities, the index in each dimension //map the index in the cities String array, as explained below: Given String[] cities={"Mannasas", "JavaCenter","Richmond"}; Assume distance between Mannasas and JavaCenter is 6, between Mannasas and Richmond is 95, then we have distance[0][1]=6; distance[0][2]=95; Required methods: Non-parameter constructor, initialize citites with 10 elements, and distance array(think about the size of this 2-D array). Constructor with single int parameter to specify the size of the cities array (as well as distance array-think about the size again!) public int getSize(); returns the size of the cities String array(its length) public int getCity(String cityName); this method returns the index of "cityName" in the cities String array, if not found returns -1 public String getCity(int index); it returns the city name in the cities String array, if not found, returns null public void addCity(String city); add a city to the cities String array if the city with the same name does not exist in the cities array. If the cities array is full, you need to expand the cities array (hint, you may want to double its size if is full). public void setDistance(String city1, String city2, int dist); set (or update) distance between these two cities. If any of the two cities does not exist in the cities array, you need to add that city to the cities array first, then set the distance in the 2-D distance array. public int getDistance(String city1, String city2); returns the distance between this two cities if a direct route exists, returns -1 if direct route between these two cities does not exists. public void initialize(File file) throws Exception; it reads data from a file to add cities and distances between cities in the file. The data fiel contains multiple lines and each line represents two cities and the distance betgween these two cities: For example: Richmond Mannasas 95 Clearwater Gainesville 131 Clearwater Miami 131 You may assume the name of all cities in the testing cases is a single word. public String getClosestCity(String city); returns the closest city if a direct route exists, otherwise returns null.

Answer 1

Screenshot

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Program

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;

//Create a class Distance
class Distance{
   //Instance variables
   String[] cities;
   int[][] distance;
   int size;
   int count;
   //default constructor
   public Distance() {
       cities=new String[10];
       size=10;
       count=0;
       distance=new int[10][10];
   }
   //Parameterized constructor
   public Distance(int sz) {
       cities=new String[sz];
       size=sz;
       count=0;
       distance=new int[sz][sz];
   }
   //Get size of the cities
   public int getSize() {
       return count;
   }
   //Get the index of city
   public int getCity(String cityName) {
       for(int i=0;i<count;i++) {
           if(cityName.equalsIgnoreCase(cities[i])) {
               return i;
           }
       }
       return -1;
   }
   //Get the city name
   public String getCity(int index) {
       if(index>=0 && index<count) {
           return cities[index];
       }
       return null;
   }
   //Add a city in to cities
   public void addCity(String city) {
       for(int i=0;i<count;i++) {
           if(city.equalsIgnoreCase(cities[i])) {
               System.out.println(city+" already in the list!!!");
               return;
           }
       }
       if(size>count) {
           cities[count]=city;
           count++;
       }
       else {
           String arr[]=new String[size*2];
           for(int i=0;i<count;i++) {
               arr[i]=cities[i];
           }
           arr[count]=city;
           cities=new String[2*size];
           cities=arr;
           count++;
           int disArr[][]=new int[2*size][2*size];
           for(int i=0;i<size;i++) {
               for(int j=0;j<size;j++) {
                   disArr[i][j]=distance[i][j];
               }
           }
           size=2*size;
       }
   }
   //Set distance
   public void setDistance(String city1, String city2, int dist) {
       boolean flag1=false,flag2=false;
       for(int i=0;i<count;i++) {
           if(city1.equalsIgnoreCase(cities[i])) {
              flag1=true;
           }
           if(city2.equals(cities[i])) {
                  flag2=true;
           }
       }
       if(flag1==false) {
           addCity(city1);
       }
       if(flag2==false) {
           addCity(city2);
       }
       int index1=getCity(city1);
       int index2=getCity(city2);
       distance[index1][index2]=dist;
   }
   //Get distance between two cities
   public int getDistance(String city1, String city2) {
       int index1=getCity(city1);
       if(index1>=0) {
           int index2=getCity(city2);
           if(index2>=0) {
               return distance[index1][index2];
           }
           else {
               return -1;
           }
       }
       else {
           return -1;
       }
   }
   //Read from a file
   public void initialize(File file) throws IOException {
       BufferedReader br = new BufferedReader(new FileReader(file));
          String line;
          while ((line = br.readLine()) != null) {
              String temp[]=line.split(" ");
              setDistance(temp[0],temp[1],Integer.parseInt(temp[2]));
          }  
   }
   //Get closest city
   public String getClosestCity(String city) {
       int min=0;
       int ind=getCity(city);
       if(ind!=-1) {
           for(int i=0;i<count;i++) {
               if(i!=ind && distance[ind][i]!=0) {
                   if(distance[ind][i]>min) {
                       min=i;  
                   }
               }
           }
           return cities[min];
       }
       else {
           return null;
       }
   }
}
public class AcmeTruckCompany {

   public static void main(String[] args) throws IOException {
       //File name
       File file=new File("C:/Users/deept/Desktop/distance.txt");
       //Create object of Distance class
       Distance distances=new Distance();
       //Read cities and distance from file
       distances.initialize(file);
       //Find distance between two cities
       System.out.println("Distance between Clearwater and Miami is "+distances.getDistance("Clearwater", "Miami"));
       System.out.println("Distance between Richmond and Mannasas is "+distances.getDistance("Richmond", "Mannasas"));
       //Find distance between two cities
       System.out.println("Closest city from Richmond is "+distances.getClosestCity("Richmond"));

   }

}

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Output

Distance between Clearwater and Miami is 131
Distance between Richmond and Mannasas is 95
Closest city from Richmond is Mannasas