Java/java-list-map/src/main/java/com/hmkcode/MapApp.java at master · Chitratech/Java · GitHub

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package com.hmkcode;

import java.util.ArrayList;

import java.util.Comparator;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import java.util.Map.Entry;

import java.util.TreeMap;

import com.hmkcode.vo.Person;

public class MapApp

{

public static void main( String[] args )

{

// ( 1 ) Map

// A. Initiate

Map<String,Person> hashMap = new HashMap<String,Person>();

Map<String,Person> treeMap = new TreeMap<String,Person>();

// B. Populate

int k = 0 ;

for(Person person:getPersons()){

hashMap.put(""+k,person);

treeMap.put(""+k++,person);

}

// --> print

System.out.println("--------- Print All -------------");

System.out.println("HashMap: "+hashMap);

System.out.println("TreeMap: "+treeMap);

// C. Iterate

// --> print

System.out.println("--------- Print Iterate by get(key) -------------");

for(String key:treeMap.keySet()){

System.out.println("treeMap: [key: "+key+" , value: "+treeMap.get(key));

}

// --> print

System.out.println("--------- Print Iterate by Entry -------------");

for(Entry<String, Person> entry:treeMap.entrySet()){

System.out.println("treeMap: [key: "+entry.getKey()+" , value: "+entry.getValue());

}

// D. Sort by value

TreeMap<String,Person> sorted_map = new TreeMap<String,Person>(new ValueComparator());

sorted_map.putAll(hashMap);

// --> print

System.out.println("--------- Print Sorted Map by Value -------------");

System.out.println("Sorted HashMap: "+sorted_map);

// E. Convert Map to List

List<Person> persons = new ArrayList<Person>(sorted_map.values());

// --> print

System.out.println("--------- Print List<Person> -------------");

System.out.println("List<Person>: "+persons);

}

private static Person[] getPersons(){

Person[] persons = new Person[5];

persons[0] = new Person("Brit", 29);

persons[1] = new Person("John", 32);

persons[2] = new Person("Jack", 27);

persons[3] = new Person("Jenifer", 24);

persons[4] = new Person("Brit", 37);

return persons;

}

class ValueComparator implements Comparator {

Map map;

public ValueComparator(){

}

public int compare(Object keyA, Object keyB){

return ((String) keyA).compareTo((String) keyB);

}

Java/java-list-map/src/main/java/com/hmkcode/MapApp.java at master · Chitratech/Java · GitHub

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