Blood is a scarce resource everywhere. Blood banks keep records of which donors

Question

Blood is a scarce resource everywhere. Blood banks keep records of which donors have which blood type. U.S. presidents travel with a supply of their own blood kept in a miniature operating room on Air Force One in case that plane comes under attack. This program processes a presidential bloodbank database. Your solution must read a list of entries consisting of a blood type followed by the presidents who share that type.

The file type2pres.txt represents a mapping of a blood type to the list of presidents who have that blood type. The tokens on each line are comma delimited. The file type2pres.txt contains:

You can easily split a comma delimited line into an array of tokens like this:

You can even use the Arrays.asList() method to put those tokens diretly into an ArrayList. This method converts a plain array to a List which is suitable to initialize an ArrayList.

STEP #1: Generate a map from bloodtype (the key) to a list of presidents (the value). Print to the screen sorted by bloodtype, and list the presidents alphabetically on the line. SEE OUTPUT.

STEP #2: Generate an inverse mapping where each president's name is a unique key and his bloodtype is the value. Print that map sorted alphabetically by president. SEE OUTPUT.

Starter File: BloodBank.java

SAMPLE OUTPUT CAPTURE

Command Prompt CNUs erst im Desktop an java an A+ B. H. Obama G. W. Bush J. F. Kennedy A. Lincoln G.A. Ford L. B. Johnson U. S. Grant W. J. Clint on B+ F. D. Roosevelt J. A. Garfield T. L. Hoffman C. A. Arthur G.Cleveland R.M.Nixon A. Lincoln B. H. alma A+ C. A. Arthur F. D. Roosevelt B+ G. A. Ford G. Cleveland G. W. Bush A+ J. A. Garfield B+ J. F. Kennedy A+ L. B. Johnson R. M. Nixon T. L. Hoffman B+ U.S. Grant W. J. Clinton C: Users tim Desktop an

Explanation / Answer

import java.io.*;
import java.util.*;

public class BloodBank
{
public static void main(String[] args) throws Exception
{
Scanner infile = new Scanner( new FileReader( "type2pres.txt" ) );
ArrayList<String> blood=new ArrayList<String>();
TreeMap<String,TreeSet<String>> map1=new TreeMap<String,TreeSet<String>> ();

TreeMap<String,String> map2=new TreeMap<String,String> ();

  
int key=0;
  
while(infile.hasNext())
{
   String[] tokens = infile.nextLine().split(",");
   ArrayList<String> p = new ArrayList<String>( Arrays.asList(tokens ));
blood.add(p.remove(0));

  
TreeSet<String> presidents = new TreeSet<String>(p);
  
map1.put(blood.get(key), presidents);
key++;    
}

  
map2=Invert(map1);

  
//displaying
  
System.out.println("map1");
for (Map.Entry<String,TreeSet<String>> entry : map1.entrySet())
       {
  
System.out.println(entry.getKey() + "/" + entry.getValue());

       }
  
  
System.out.println("map2");

for (Map.Entry<String, String> entry : map2.entrySet())
{
System.out.println(entry.getKey() + "/" + entry.getValue());
}

  

} // MAIN
  
  
public static TreeMap<String,String> Invert( TreeMap<String,TreeSet<String>> map)
{
  
TreeMap<String,String> inv=new TreeMap<String,String> ();

  
       for (Map.Entry<String,TreeSet<String>> entry : map.entrySet())
       {
       for(String president: entry.getValue())
       {
           inv.put(president, entry.getKey());
       }
       }   
   return inv;
  
  
  
}
  
  
  
} // BLOODBANK

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