How to use a counter inside a Hashmap?

Question

It is possible to do this?

public static void main(String[] args) {

    Scanner in = new Scanner (System.in);

    Map <String,Integer> mapa = new HashMap <String,Integer>();

    mapa.put("45 - Jose"  , ? ); //A "Key" deve ser o numero do Candidato,        
    mapa.put("13 - Maria" , ? ); // e  o "Value" o contador  que vai 
    mapa.put("20 - Pedro" , ? ); // contabilizar os votos,  porem nao sei
    mapa.put("50 - Carol" , ? ); // como criar  o contador aqui.      

    for (Map.Entry <String , Integer> conteudo : mapa.entrySet()){

        System.out.println(conteudo.getKey());

        System.out.printf("Votos = %d \n",conteudo.getValue());
    }

    String key, continuar;

    do{

    System.out.println("\nEm que candidato deseja votar? ");
    key =  in.nextLine();

    if (mapa.containsKey(key)){
        mapa.replace(key, new Integer (?));

        System.out.printf("\nCandidato: %s \nVotos = %d \n", key, mapa.get(key));  
    }else{
        System.err.printf("\nCandidato %s nao encontrado.\n" ,key);
    }

    System.out.println("\nDeseja continuar: (s/n)");
    continuar = in.nextLine();

    }while("s".equalsIgnoreCase(continuar));

Answer 1

To initialize the counter just put zero, as you would normally do. To increment you have to take the current value and already know that you do this with the method get() and to put the new value already knows that it is with put(), just need to join the two, obviously adding one to the found value before saving the new one, as always done on any counter. I mean, there’s nothing I couldn’t do.

import java.util.*;
class Ideone {
    public static void main(String[] args) {
        Scanner in = new Scanner (System.in);
        Map<String,Integer> mapa = new HashMap<String,Integer>();
        mapa.put("45 - Jose"  , 0); //A "Key" deve ser o numero do Candidato,        
        mapa.put("13 - Maria" , 0); // e  o "Value" o contador  que vai 
        mapa.put("20 - Pedro" , 0); // contabilizar os votos,  porem nao sei
        mapa.put("50 - Carol" , 0); // como criar  o contador aqui.      
        for (Map.Entry<String, Integer> conteudo : mapa.entrySet()) {
            System.out.println(conteudo.getKey());
            System.out.printf("Votos = %d \n", conteudo.getValue());
        }
        String continuar;
        do {
            System.out.println("\nEm que candidato deseja votar? ");
            String key =  in.nextLine();
            if (mapa.containsKey(key)) {
                mapa.put(key, mapa.get(key) + 1);
                System.out.printf("\nCandidato: %s \nVotos = %d \n", key, mapa.get(key));  
            } else {
                System.err.printf("\nCandidato %s nao encontrado.\n", key);
            }
            System.out.println("\nDeseja continuar: (s/n)");
            continuar = in.nextLine();
        } while ("s".equalsIgnoreCase(continuar));

    }
}

Behold working in the ideone. And in the repl it.. Also put on the Github for future reference.

It would also be nice to maintain consistency in code organization.