Module# 09: Table and Map Lecture#39: Applications of Map Part-II

// Example 39.1: Creating a Map container as a TreeMap class object

// Illustrates the creation of a map container

import java.util.*;

class TreeMapDemo {

public static void main(String args[]) {

// Create a tree map.

TreeMap<String, Double> tm = new TreeMap<String, Double>();

// Put elements to the map.

tm.put("John Doe", new Double(3434.34));

tm.put("Tom Smith", new Double(123.22));

tm.put("Jane Baker", new Double(1378.00));

tm.put("Tod Hall", new Double(99.22));

tm.put("Ralph Smith", new Double(-19.08));

// Get a set of the entries.

Set<Map.Entry<String, Double>> set = tm.entrySet();

// Display the elements.

for(Map.Entry<String, Double> me : set) {

System.out.print(me.getKey() + ": ");

System.out.println(me.getValue());

}

System.out.println();

// Deposit 1000 into John Doe's account.

double balance = tm.get("John Doe");

tm.put("John Doe", balance + 1000);

System.out.println("John Doe's new balance: " + tm.get("John Doe"));

}

}

// Example 39.2: Managing a Map container as a LinkedHashMap class object

/* This program illustrates the creation of a Map object using LinkedHashMap class */

import java.util.*;

class LinkedHashMapDemo {

private static final int MAX = 6; // Refers to the max size of the map

public static void main(String args[]) {

// Creating the linked hashmap and implementing removeEldestEntry() to MAX size

LinkedHashMap<Integer, String>lhm =

new LinkedHashMap<Integer, String>() {

protected Boolean removeEldestEntry(Map.Entry<Integer, String> eldest) {

return size() > MAX;

}

};

// Adding elements using put()

lhm.put(0, "Welcome");

lhm.put(1, "To");

lhm.put(2, "The");

lhm.put(3, "World");

lhm.put(4, "Of");

lhm.put(5, "Java");

System.out.println("" + lhm);

// Adding more elements

lhm.put(6, "Joy with Java");

// Displying the map after adding one more element

System.out.println("" + lhm);

// Adding more elements

lhm.put(7, "Hello");

// Displying the map after adding one more element

System.out.println("" + lhm);

}

}

// Example 39.3: Map container with user defined data type

/* This example illustrates how a map container will be with objects of Book class. */

import java.util.*;

class Book {

int id;

String name,author,publisher;

int quantity;

public Book(int id, String n, String a, String p, int q){

this.id = id;

name = n;

author = a;

publisher = p;

quantity = q;

}

}

/* This example illustrates how a map container will be with objects of Book class. */

import java.util.*;

class Book {

int id;

String name,author,publisher;

int quantity;

public Book(int id, String n, String a, String p, int q){

this.id = id;

name = n;

author = a;

publisher = p;

quantity = q;

}

}

public class MapBookDataExample {

public static void main(String[] args) {

//Creating map of Books

Map<Integer,Book> map=new LinkedHashMap<Integer,Book>();

//Creating Books

Book b1=new Book(101,"Python","Ponting","Oxford",8);

Book b2=new Book(102,"Java","Spielberg","McGraw Hill",4);

Book b3=new Book(103,"C++","Galvin","Wiley",6);

//Adding Books to map

map.put(2,b2);

map.put(1,b1);

map.put(3,b3);

//Traversing map

for(Map.Entry<Integer, Book>entry:map.entrySet()){

int key=entry.getKey();

Book b=entry.getValue();

System.out.println(key+" Details:");

System.out.println(b.id+" "+b.name+" "+b.author+" "+b.publisher+" "+b.quantity);

}

}

}

// Example 39.4: A Map container using EnumMap class

/* This Java program illustrates working of EnumMap and its functions. */

import java.util.EnumMap;

public class EnuMapExample {

public enum SIZE {S, M, L, X };

public static void main(String args[]) {

// Creating EnumMap in java with key as enum type STATE

EnumMap<SIZE, String>enuMap = new EnumMap<SIZE, String>(SIZE.class);

//Putting values inside EnumMap in Java

// Inserting Enum keys different from their natural order

enuMap.put(SIZE.S, "Children");

enuMap.put(SIZE.M, "Young");

enuMap.put(SIZE.L, "Aged");

enuMap.put(SIZE.X, "Old");

// Printing size of EnumMap in java

System.out.println("Size of EnumMap in java: "+ enuMap.size());

// Printing Java EnumMap

System.out.println("EnumMap: "+ enuMap);

// Retrieving value from EnumMap in java

System.out.println("Key : "+ SIZE.S +" Value: " +

enuMap.get(SIZE.S));

}

}

// Example 39.5: Synchronized (thread-safe) Map

import java.util.*;

class HashMapBulkOperationDemo1 {

public static void main(String args[]) {

// Create two map object containers.

Map<Integer, String> map = Collections.synchronizedMap(new HashMap<>());

// Creatin a map

map.put(400, "Bad Request");

map.put(304, "Not Modified");

map.put(200, "OK");

map.put(301, "Moved Permanently");

map.put(500, "Internal Server Error");

Set<Integer>keySet = map.keySet();

synchronized(map) {

Iterator<Integer> iterator = keySet.iterator();

while(iterator.hasNext()) {

Integer key = iterator.next();

String value = map.get(key);

}

}

}

}