Find the element with the highest number

Question

I’m doing a basic election system, but I have a problem telling which candidate was elected. In this case, I added three candidates (x, y, z) to a ArrayList, I put two votes on x, three on y and four on z. When I want to know which one won (in this case which got the most votes) he prints all 3 candidates.

public void eleitoPresidente() {
    int maior = 0;
    for (Candidato e: candidato) {
        if(e.votos > maior) {
            maior = e.votos;
            System.out.println("O presidente eleito é: " + e.nome);
        }
    }
}

I want him to print only the candidate with the largest number of votes.

Answer 1

Keeping the algorithm you did initially has two problems, it is not keeping which is the biggest anywhere. And it is saying who was elected every time a new candidate evaluated has more votes than the previous one. So the correct one would be:

import java.util.*;

class HelloWorld {
    public static void main (String[] args) {
        ArrayList<Candidato> candidato = new ArrayList<>();
        candidato.add(new Candidato("joao", 4));
        candidato.add(new Candidato("jose", 2));
        candidato.add(new Candidato("joaquim", 7));
        int maiorVotos = 0;
        Candidato maiorCandidato = null;
        for (Candidato e: candidato) {
            if(e.votos > maiorVotos) {
                maiorVotos = e.votos;
                maiorCandidato = e;
            }
        }
        if (maiorCandidato != null) {
            System.out.println("O presidente eleito é: " + maiorCandidato.nome);
        }
    }
}

class Candidato {
    public String nome;
    public int votos;
    public Candidato (String nome, int votos) {
        this.nome = nome;
        this.votos = votos;
    }
}

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

Answer 2

You can use the method Collections.sort(List<T>, Comparator<? super T>) to order candidates by some criterion (in this case the number of votes in descending order), and then take the first of them:

public void eleitoPresidente() {
    List<Candidato> copia = new ArrayList<>(candidato);
    Collections.sort(copia, (a, b) -> b.votos - a.votos);
    System.out.println("O presidente eleito é: " + copia.get(0).nome);
}

Answer 3

That way it will work

public void eleitoPresidente() {
    Candidato maiorCand = null;
    int maior = 0;
    for (Candidato e : candidato) {
        if (e.votos > maior) {
            maiorCand = e;
        }
    }
    if (maiorCand != null) {
        System.out.println("O presidente eleito é: " + maiorCand.nome);
    } else {
        System.out.println("Não teve presidente eleito");
    }
}