Calculations of skinfolds

Question

Well, I don’t know if I can ask for help in calculating, more anyway, my question is this::

I need to do the calculation of skin folds, in this case the calculation of Pollok 3 folds, I researched on the internet, but it is not something so easy to understand, I would like to know, if the way I am doing this correct. I was going to post only the calculation, but I also made an executable example (very simple example) to illustrate the better situation.

I used this information as a basis:

Para 3 dobras:
DC= 1,10938 – 0,0008267 (X2) + 0,0000016 (X2)
2 – 0, 0002574 (X3)
Legenda:
DC= Densidade Corporal em g/ml    
X2 = soma das 3 dobras (tórax, abdominal e coxa)
X3 = idade em anos 

Note: page 36 : https://sandrodesouza.files.wordpress.com/2010/05/perimetria-dobras-cutaneas-e-protocolos.pdf

Code:

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class DobrasCuteneas extends JFrame {

    JTextField campoPeitoral = new JTextField();
    JTextField campoAbdominal = new JTextField();
    JTextField campoCoxa = new JTextField();
    JTextField campoGorduraIdeal = new JTextField();
    JButton botao = new JButton("Calcular");

    public DobrasCuteneas() {
        setTitle("Exemplo");
        add(tela());
        pack();
        acaoBotao();
        setLocationRelativeTo(null);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

    }

    private void acaoBotao() {
        botao.addActionListener((ActionEvent ae)
                -> {
            calculo();
        });
    }

    private JPanel tela() {
        JPanel painel = new JPanel();
        JLabel label01 = new JLabel("Peitoral:");
        painel.add(label01);
        painel.add(campoPeitoral);
        campoPeitoral.setPreferredSize(new Dimension(100, 20));
        JLabel label02 = new JLabel("Abdominal:");
        painel.add(label02);
        painel.add(campoAbdominal);
        campoAbdominal.setPreferredSize(new Dimension(100, 20));
        JLabel label03 = new JLabel("Coxa:");
        painel.add(label03);
        painel.add(campoCoxa);
        campoCoxa.setPreferredSize(new Dimension(100, 20));
        painel.add(botao);
        botao.setPreferredSize(new Dimension(90, 20));
        JLabel label04 = new JLabel("Gordura ideal:");
        painel.add(label04);
        painel.add(campoGorduraIdeal);
        campoGorduraIdeal.setPreferredSize(new Dimension(100, 20));
        add(painel);

        return painel;
    }

    private void calculo() {
        float peitoral = Float.valueOf(campoPeitoral.getText().replaceAll(",", "."));
        float abdominal = Float.valueOf(campoAbdominal.getText().replaceAll(",", "."));
        float coxa = Float.valueOf(campoCoxa.getText().replaceAll(",", "."));
        float idade = 25;
        Float x2 = (peitoral + abdominal + coxa);

        Float densidadeCorporal = (float) (1.10938 - x2) + (x2 * 2) - idade;
        System.out.println("Densidade corporal: " + densidadeCorporal);
        Float percentualGordura = ((float) ((4.95 / densidadeCorporal) - 4.50) * 100);
        System.out.println("Percentual de gordura: " + percentualGordura);
        campoGorduraIdeal.setText("" + percentualGordura);
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(()
                -> {
            DobrasCuteneas dobras = new DobrasCuteneas();
            dobras.setVisible(true);
        });
    }
}

And for the final calculation (ideal fat) :

%G = [(4,95/Densidade Corporal) - 4,50] x 100

Answer 1

The formula for body density lacked the coefficients as well as the square of X2. Remembering that the same is (by the pdf indicated):

DC= 1,10938 - 0,0008267 (X2) + 0,0000016 (X2) 2 - 0,0002574 (X3)

And that was applied as:

Float densidadeCorporal = (float) (1.10938 - x2) + (x2 * 2) - idade;

The coefficients of 0,0008267, 0,0000016 and 0,0002574 were not used.

To fix just change the formula to:

Float densidadeCorporal = 1.10938 - (0.0008267 * x2) + (0.0000016 * x2 * x2) - (0.0002574 * idade);