COP 3530
Section U03
Fall 2017



                              Some Set and Some Map Programs
                              ==============================




I. The first program forms a hash set. Notice that the entries are not in alphabetical 
   order and no duplications are allowed. We can use the enhanced for loop.

import java.util.*;
// set sets
public class Sets 
{
    public static void main(String[] args) 
    {
        System.out.println("Test Sets");
        System.out.println("=========\n\n");
        
        Set<String> set = new HashSet<>();
        System.out.println("We form a set with Papa Bill, Markey, "
                + " Markey, Zoila, Shrek, Zoila.");
        
        set.add("Papa Bill");
        set.add("Markey");
        set.add("Markey"); //ignored, no duplications
        set.add("Zoila");
        set.add("Shrek");
        set.add("Zoila"); // ignored, no duplications
        
        System.out.println("\nThe set is:");
        for (String s: set)
            System.out.println(s);
        
    }
}


The output:

run:
Test Sets
=========


We form a set with Papa Bill, Markey,  Markey, Zoila, Shrek, Zoila.

The set is:
Shrek
Zoila
Markey
Papa Bill
BUILD SUCCESSFUL (total time: 1 second)

2. The second program uses a tree set and is more elaborate.
   We used the reversed alphabetical order and we used the methods headSet
   and tailSet. Notice that if we remove an item from the head set, 
   it is removed from the set, so we only get a segment of the set, not
   a new set.

import java.util.*;
/**
 *
 * @author pelina
 */
public class Main {
       
    public static void main(String[] args) 
    {
        System.out.println("We form a tree set with the names:");
        System.out.println("bob, al, markey, geoff, ali baba, rose, zoila, al.");
        System.out.println("We use the reverse comparator for ordering the data.");
        SortedSet<String> s = new TreeSet<String>(Collections.reverseOrder());
        s.add("bob");
        s.add("al");
        s.add("markey");
        s.add("geoff");
        s.add("ali baba");
        s.add("rose");
        s.add("zoila");
        s.add("al"); // useless add

        // print the collection
        System.out.println("The set is:");
        for (String val: s)
            System.out.println(val);

        // print the smallest and the largest
        String small = s.first();
        String large = s.last();
        System.out.println("\nThe smallest is " + small);
        System.out.println("The largest is " + large);
        SortedSet<String> pre = s.headSet("geoff");
        SortedSet<String> post = s.tailSet("kip");
        System.out.println("The set pre, i.e. the items < Geoff are:");
        for (String val: pre)
            System.out.println(val);
        System.out.println("The items >= kip are:");
        for (String val: post)
            System.out.println(val);
        
        System.out.println("\nWe try to remove the markey from pre.");
        if (s.remove("markey"))
            System.out.println("markey was removed.");
        else
            System.out.println("markey was not removed.");
        System.out.println("\nNow print pre.");
        for (String val: pre)
            System.out.println(val);
        System.out.println("\nNow print the set.");
        for (String val: s)
            System.out.println(val);
        
    }
    
}

The output:
 
run:
We form a tree set with the names:
bob, al, markey, geoff, ali baba, rose, zoila, al.
We use the reverse comparator for ordering the data.
The set is:
zoila
rose
markey
geoff
bob
ali baba
al

The smallest is zoila
The largest is al
The set pre, i.e. the items < Geoff are:
zoila
rose
markey
The items >= kip are:
geoff
bob
ali baba
al

We try to remove the markey from pre.
markey was removed.

Now print pre.
zoila
rose

Now print the set.
zoila
rose
geoff
bob
ali baba
al
BUILD SUCCESSFUL (total time: 1 second)

3. The 3rd program shows how to use a map. We used a tree map and a separate method 
   for printing a map. The main method formed a map using the put method and showed 
   how to use the methods get, keySet, and values. Notice that we remove a key from 
   the key set or a value from the value set, the corresponding entry(ies) re removed.


package maptest;
import java.util.Map;
import java.util.TreeMap;
import java.util.Set;
import java.util.Collection;
/**
 *
 * @author pelina
 */
public class Main {

    // print a map
    public static <KeyType,ValueType>
    void printMap(String msg, Map<KeyType,ValueType> m) 
    {
        System.out.println(msg + ":");
        Set<Map.Entry<KeyType,ValueType>> entries = m.entrySet();
        
        for ( Map.Entry<KeyType, ValueType> thisPair :entries)
        {
            System.out.print(thisPair.getKey() + "; ");
            System.out.println(thisPair.getValue());
        }    
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        Map<String,String> phone1 = new TreeMap<String,String>();
        
        phone1.put("Mark", "(305)111-1111");
        phone1.put("Bill", "(305)222-2222");
        phone1.put("Mary", "(305)333-3333");
        phone1.put("Carol", "(305)444-4444");
        phone1.put("Dan", "(305)555-5555");
        phone1.put("Mark", "(305)666-6666"); 
        // print the map
        System.out.println("The map:");
        printMap("phone 1", phone1);

        //
        System.out.println("phone1.get(\"Carol\"): " +
                phone1.get("Carol"));

        // print the keys
        System.out.println("\nThe keys are: ");
        Set<String> keys = phone1.keySet();
         // print the collection
        for (String val: keys)
            System.out.println(val);  
        
        System.out.println("\nThe values are: ");
        Collection<String> values = phone1.values();
         // print the collection
        for (String val: values)
            System.out.println(val);

        keys.remove("Susan");
        keys.remove("Mary");
        values.remove("(305)222-2222");



        System.out.println("After Susan, Mary and (305)222-2222 are removed");
        System.out.println("\nThe map is: ");
        printMap("phone 1", phone1);
    }
    
}

The output:
  
run:
The map:
phone 1:
Bill; (305)222-2222
Carol; (305)444-4444
Dan; (305)555-5555
Mark; (305)666-6666
Mary; (305)333-3333
phone1.get("Carol"): (305)444-4444

The keys are: 
Bill
Carol
Dan
Mark
Mary

The values are: 
(305)222-2222
(305)444-4444
(305)555-5555
(305)666-6666
(305)333-3333
After Susan, Mary and (305)222-2222 are removed

The map is: 
phone 1:
Carol; (305)444-4444
Dan; (305)555-5555
Mark; (305)666-6666
BUILD SUCCESSFUL (total time: 0 seconds)

4. The 4th program uses a hash map.
   Again, we use put to create a map, and Map.Entry to print 
   the pairs. We used Map.remove to remove an entry.


import java.util.*;

// test maps
public class TestMaps 
{

    public static void main(String[] args) 
    {
        System.out.println("Maps");
        System.out.println("====\n\n");
        
        System.out.println("Form the Husband of map.");
        Map<String,String> map = new HashMap<>();
        
        // add some pairs
        map.put("Jaime","Papa Bill");
        map.put("Jill", "Mark");
        map.put("Zoila", "Jorge");
        map.put("Ana", "Jorge");
        map.put("Karen", "Papa Bill");
        map.put("Christine", null);
        
        System.out.println("\nPrint the map.");
        Set<Map.Entry<String,String>> set = map.entrySet(); 
        for (Map.Entry<String,String> pair : set)
        {
            String key = pair.getKey();
            String value = pair.getValue();
            System.out.println("The husband of " + key + " is "
                    + value + ".");
        }    
        
        // Now let us say that Christine gets married to Hugo
        System.out.println("\nChristine gets married to Hugo.");
        map.remove("Christine");
        map.put("Christine", "Hugo");        
        System.out.println("\nPrint the map.");
        for (Map.Entry<String,String> pair : set)
        {
            String key = pair.getKey();
            String value = pair.getValue();
            System.out.println("The husband of " + key + " is "
                    + value + ".");
        }    
        
        
    }
}

The output:

run:
Maps
====


Form the Husband of map.

Print the map.
The husband of Jaime is Papa Bill.
The husband of Zoila is Jorge.
The husband of Karen is Papa Bill.
The husband of Ana is Jorge.
The husband of Jill is Mark.
The husband of Christine is null.

Christine gets married to Hugo.

Print the map.
The husband of Jaime is Papa Bill.
The husband of Zoila is Jorge.
The husband of Karen is Papa Bill.
The husband of Ana is Jorge.
The husband of Jill is Mark.
The husband of Christine is Hugo.
BUILD SUCCESSFUL (total time: 0 seconds)