Question

Consider the following client class:

import java.util.Collection;

import java.util.Collections;

import java.util.HashMap;

import java.util.Map;

import java.util.Set;

public class PresidentsMain {

public static void main(String[] args) {

Map<String, String> PresidentsOfTheUnitedStates = new HashMap<String, String>();

PresidentsOfTheUnitedStates.put("George Washington", "Unaffiliated");

PresidentsOfTheUnitedStates.put("John Adams", "Federalist");

PresidentsOfTheUnitedStates.put("Thomas Jefferson", "Democratic-Republican");

PresidentsOfTheUnitedStates.put("James Madison", "Democratic-Republican");

PresidentsOfTheUnitedStates.put("James Monroe", "Democratic-Republican");

PresidentsOfTheUnitedStates.put("John Quincy Adams", "Democratic-Republican");

PresidentsOfTheUnitedStates.put("Andrew Jackson", "Democratic");

PresidentsOfTheUnitedStates.put("Martin Van Buren", "Democratic");

PresidentsOfTheUnitedStates.put("William Henry Harrison", "Whig");

PresidentsOfTheUnitedStates.put("John Tyler", "Whig");

     }

}

}

Extend given client class:

• Implement a static method called FilterMapByValue, that takes 2 parameters:
  • Map<String, String> InMap;
  • String TargetValue;

Method should print out all map elements, for which Value == TargetValue. Test the implementation by filtering PresidentsOfTheUnitedStates map so that only presidents, affiliated with Democratic-Republican party are printed. Note: use the following to iterate over a map:

  for (Map.Entry<String,String> Entry : InMap.entrySet())   

• Implement a method PrintValues, that prints all values for a given map (use map’s values() function). Test the implementation on PresidentsOfTheUnitedStates map.
• Implement a method PrintKeys, that prints all keys for a given map (use map’s keySet() function). Test the implementation on PresidentsOfTheUnitedStates map.

Answer 1

Note: Declare both these classes under the same package name and run the code from PresidentsMain class

package com.tavant.training; //PresidentsMain class

import java.util.Collection;

import java.util.Collections;

import java.util.HashMap;

import java.util.Map;

import java.util.Set;

public class PresidentsMain {

   public static void main(String[] args) { //RUN THE PROGRAM FROM HERE

       Map<String, String> PresidentsOfTheUnitedStates = new HashMap<String, String>();

       PresidentsOfTheUnitedStates.put("George Washington", "Unaffiliated");

       PresidentsOfTheUnitedStates.put("John Adams", "Federalist");

       PresidentsOfTheUnitedStates.put("Thomas Jefferson", "Democratic-Republican");

       PresidentsOfTheUnitedStates.put("James Madison", "Democratic-Republican");

       PresidentsOfTheUnitedStates.put("James Monroe", "Democratic-Republican");

       PresidentsOfTheUnitedStates.put("John Quincy Adams", "Democratic-Republican");

       PresidentsOfTheUnitedStates.put("Andrew Jackson", "Democratic");

       PresidentsOfTheUnitedStates.put("Martin Van Buren", "Democratic");

       PresidentsOfTheUnitedStates.put("William Henry Harrison", "Whig");

       PresidentsOfTheUnitedStates.put("John Tyler", "Whig");
      
       ExtendedClass object=new ExtendedClass(); // object of newly created extendedClass is made
      
       object.FilterMapByValue(PresidentsOfTheUnitedStates, "Democratic-Republican"); //FilterMapByValue method call
      
       object.PrintValues(PresidentsOfTheUnitedStates); //PrintValues method call
      
       object.PrintKeys(PresidentsOfTheUnitedStates); //PrintKeys method call    

       }

       }

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

package com.tavant.training; //  ExtendedClass

import java.util.Map;

public class ExtendedClass {
  
   public void FilterMapByValue(Map<String, String> InMap,String TargetValue) // accepts map to InMap and the string
   {
       for (Map.Entry<String,String> Entry : InMap.entrySet())
       {
           if(Entry.getValue()==TargetValue) // check if value equals target value or not
           System.out.println("key:"+Entry.getKey()+"and value:"+Entry.getValue()); //if condition satisfies, key
       } //value pair is printed
   }
  
   public void PrintValues(Map<String, String> InMap)
   {
       System.out.println(InMap.values()); // values() function implemented
   }

   public void PrintKeys(Map<String, String> InMap)
   {  
       System.out.println(InMap.keySet()); // keySet() function implemented
   }

}