Percentage in Java

Question

Business rule: A program that receives the code of a user, the Qtd in Kwh q he consumes and the type of it that can be 3: each type multiplies the cost of energy consumed as the constants are defined at the beginning of the program, all this while the user does not enter the code 0, i.e., the program will receive more data while the entered code is not 0. Finally the program should return some things such as the cost to each user ( defined only by each entered code), the total cost for each type inserted by the program until its termination (the program sums up the costs for each type), the cost average for type 2 users and finally the percentage of type 3 users who used the program.

Follows the code:

public class Problema01 {

    static double tipo1 = 1.5, tipo2 = 3.0, tipo3 = 5.0;

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        int entrada, tipo, codigo, qtd0 = 0, qtd = 0, qtd1 = 0, qtdTotal = 0;
        double porcentagem = 0, consumido, custoTotal, soma0 = 0, soma = 0, soma1 = 0, media = 0;

        do {

        System.out.println("Digite o código do consumidor: ");
                codigo = sc.nextInt();

                System.out.println("Digite a quantidade consumida em KWh: ");
                consumido = sc.nextInt();

                System.out.println("Digite o tipo de consumidor: ");
                tipo = sc.nextInt();

                if (tipo == 1) {
                    qtd0 = qtd0 + 1;
                    custoTotal = tipo1 * consumido;
                    soma0 = soma0 + custoTotal;
                    System.out.println("Valor da conta do usuário " + codigo + " é: " + custoTotal);

                } else if (tipo == 2) {
                    qtd = qtd + 1;
                    custoTotal = tipo2 * consumido;
                    soma = soma + custoTotal;
                    media = soma / qtd;
                    qtdTotal = qtd0 + qtd + qtd1;        
                    System.out.println("Valor da conta do usuário " + codigo + " é: " + custoTotal);
                } else if (tipo == 3) {
                    qtd1 = qtd1 + 1;
                    custoTotal = tipo3 * consumido;
                    soma1 = soma1 + custoTotal;                                       
                    System.out.println("Valor da conta do usuário " + codigo + " é: " + custoTotal);
                }

                qtdTotal = qtd0 + qtd + qtd1;
                porcentagem = qtd1 / qtdTotal * 100.0f;

                System.out.println("Total tipo 1: " + soma0);
                System.out.println("Total tipo 2: " + soma);
                System.out.println("Total tipo 3: " + soma1);
                System.out.println("Media custo tipo 2: " + media);
                System.out.println("Tipo 3 (em porcentagem): " + porcentagem + "%");

              }  while (codigo != 0);        

        }

    }

The last output asks for the percentage of type 3 users but is not coming out correctly. What is wrong?

Input example: 1, 10, 1, Exit: User account value 1 is: 15.0, Total type 1: 15.0, Total type 2: 0.0, Total type 3: 0.0, Average cost type 2: 0.0, Type 3 (as a percentage): 0.0%

Next entry: 2, 10, 3, Exit: User account value 2 is: 50.0, Total type 1: 15.0, Total type 2: 0.0, Total type 3: 50.0, Average cost type 2: 0.0, Type 3 (as a percentage): 0.0%

As in the example above, a user of type 1 was entered and then a user of type 3, my expected output was 0% for the first input and 50% in the second since there were two types and one of them was type 3.

Answer 1

I rewrote your problem because although the error is due to division of int for int,the variable names confused. Then I followed as default put the number referring to the type right after the variable name. I also created variables only in their scope of use. The result was the following:

import java.util.Scanner;

public class Energia {

  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int codigo;

    int quantidade1 = 0;
    int quantidade2 = 0;
    int quantidade3 = 0;

    double multiplicador1 = 1.5;
    double multiplicador2 = 3;
    double multiplicador3 = 5;

    double total1 = 0;
    double total2 = 0;
    double total3 = 0;

    do {
      double consumido;
      int tipo;
      double custoTotal = 0;
      double quantidadeTotal;
      double porcentagem3;
      double media2 = 0;

      System.out.println("Digite o código do consumidor: ");
      codigo = sc.nextInt();

      System.out.println("Digite a quantidade consumida em KWh: ");
      consumido = sc.nextDouble();

      System.out.println("Digite o tipo de consumidor: ");
      tipo = sc.nextInt();

      switch (tipo) {
        case 1:
          quantidade1 = quantidade1 + 1;
          custoTotal = multiplicador1 * consumido;
          total1 = total1 + custoTotal;
          break;
        case 2:
          quantidade2 = quantidade2 + 1;
          custoTotal = multiplicador2 * consumido;
          total2 = total2 + custoTotal;
          break;
        case 3:
          quantidade3 = quantidade3 + 1;
          custoTotal = multiplicador3 * consumido;
          total3 = total3 + custoTotal;
          break;
      }

      System.out.println("Valor da conta do usuário " + codigo + " é: " + custoTotal);

      quantidadeTotal = quantidade1 + quantidade2 + quantidade3;
      media2 = total2 / quantidade2;
      porcentagem3 = quantidade3 / quantidadeTotal * 100;

      System.out.println("Total tipo 1: " + total1);
      System.out.println("Total tipo 2: " + total2);
      System.out.println("Total tipo 3: " + total3);
      System.out.println("Media custo tipo 2: " + media2);
      System.out.println("Tipo 3 (em porcentagem): " + porcentagem3 + "%");
    } while (codigo != 0);
  }
}