Question

How is this method coded in java?

int differential(int[] post)

differential computes the virtual differential for a single post record and returns the differential. The differential is simply the difference between ups and downs. differential is virtual because it is not stored in a post record.

/// Compute the differential between "ups" (at index 1) and "downs"

  /// (at index 2). The differential is not maintained in the data but is a

  /// virtual field derived by the calculation performed here

  public static int differential(int[] post) {

    // TODO : Implement Here

    return 0;

  }

Post data:

0001 505361 236677

0002 629710 727941

0003 414780 842861

0004 702957 401854

0005 862865 315572

0006 930013 609421

0007 326101 220500

0008 732457 404837

0009 878259 411163

0010 227645 638470

Answer 1

One of the thing you failed to metion that from where these values are coming. I want to ask that if we are reading these values from a file or they are simply stored in the code.

Here I am providing the solution by simply assuming that we are reading thses values from a file.

Also please not that save the text file in same folder where is your java code.

Working: We simply raead each line from a file and pass to the method as an array where it calculates the differential and return in int which will we print on console.

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Code:

import java.util.*;
import java.io.File;
import java.nio.file.Path;
import java.nio.file.Paths;

class Main
{
  
   //method to calculate virtual differential
   public static int differential(int[] post) {

//return the difference of ups (at index 1) to downs (at index 2)
return post[1] - post[2];

}
  
//execution of program starts from here
public static void main(String[] args)
{
       String fileName = "data.txt" ; //save this file in same folder where your java file is stored.
      
       try
       {
           Path path = Paths.get(fileName);
           Scanner scanner = new Scanner(path);
           System.out.println("Reading all tweets from file:\n");
          
           //read each number line by line
           while(scanner.hasNextLine()){
              
               //create an array
               int arr[] = new int[3];
              
               //tweet number
               arr[0] = Integer.parseInt(scanner.next());
               arr[1] = Integer.parseInt(scanner.next()); //ups
               arr[2]= Integer.parseInt(scanner.next()); //downs
              
               //pass these values to method as an array
               int count = differential(arr);
              
               //print the result
               System.out.println("Tweet Num: " + arr[0] + " Virtual Differential: " + count);
           }
           scanner.close();
       }
       catch(Exception e)
       {
           System.out.println("Unable to read file");
       }
  
}
}

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Output: