Java multiple CheckBoxes

Question

I have problem with multiple CheckBoxes. When I create them with my code it only show last box "bolonska zmes" and other boxes are shown only when mouseover. I think that it might be some problem with layers, but I dont know what to do. Thank you for help.

  public class OknoPizzaVlastna extends JFrame
    {
         private String nazvy[] = { "cesnak", "feferony", "hrasok", "cibula",
         "kecup", "tatarskaOmacka", "vajce",
         "kapia", "fazula", "kukurica", "ananas", "brokolica",
         "Niva", "Mozarella", "olivy", "inovec udeny", "articoky",
         "klobasa", "sampiony", "salama", "slanina", "hranolky", "tuniak",
         "sunka", "kuracie maso", "syr", "Morska zmes", "bolonska zmes"};

         private JCheckBox boxes[];

        public OknoPizzaVlastna()
        {
            boxes = new JCheckBox[nazvy.length];

            for (int i = 0; i < nazvy.length; i++) 
            {            
                createrCheckBox(i);          
            }

            setTitle("Vlastna Pizza");
            setSize(480,320);
            setVisible(true);
            setResizable(true);

            getContentPane().setLayout(null);
            setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        }

        public void createrCheckBox(int i)
        {
            boxes[i] = new JCheckBox();
            //proper locations will be solved later
            boxes[i].setLocation(62+i*30,54+i*20); 
            boxes[i].setSize(100,50);
            boxes[i].setText(nazvy[i]);
            boxes[i].setSelected(false);
            boxes[i].setVisible(true);
            getContentPane().add(boxes[i]);  
        } 
    }

Answer 1

If the question were, 'how to layout this GUI?' the answer might be:

To organize the components for a robust GUI, use layout managers, or combinations of them, along with layout padding & borders for white space.

In this case, we use a single column GridLayout, with an EmptyBorder on each check box to successively indent them a larger amount as we proceed down the menu.

import java.awt.*;
import javax.swing.*;
import javax.swing.border.*;

public class OknoPizzaVlastna extends JFrame {

    private String nazvy[] = {
        "cesnak", "feferony", "hrasok", "cibula",
        "kecup", "tatarskaOmacka", "vajce",
        "kapia", "fazula", "kukurica", "ananas", "brokolica",
        "Niva", "Mozarella", "olivy", "inovec udeny", "articoky",
        "klobasa", "sampiony", "salama", "slanina", "hranolky", "tuniak",
        "sunka", "kuracie maso", "syr", "Morska zmes", "bolonska zmes"
    };

    JPanel ui= new JPanel(new GridLayout(0,1,4,4));

    private JCheckBox boxes[];

    public OknoPizzaVlastna() {
        ui.setBorder(new EmptyBorder(10,10,10,10));
        setContentPane(ui);
        boxes = new JCheckBox[nazvy.length];

        for (int i = 0; i < nazvy.length; i++) {
            createrCheckBox(i);
        }

        setTitle("Vlastna Pizza");
        pack();
        setVisible(true);
        setResizable(true);
        setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
    }

    public void createrCheckBox(int i) {
        boxes[i] = new JCheckBox(nazvy[i]);
        boxes[i].setBorder(new EmptyBorder(0,i*30,0,0));
        ui.add(boxes[i]);
    }

    public static void main(String[] args) {
        Runnable r = new Runnable() {
            public void run() {
                JFrame frame = new OknoPizzaVlastna();
            }
        };
        SwingUtilities.invokeLater(r);
    }
}