Question

I have a small question – how can I repaint JPanel in the main class from other classes/files/methods?

The story is, that I have a Swing window, which has a list of methods, which are automatically generated by going through files and classes in the folder, and reading methods with their descriptions (annotations). Now, the thing is that when there comes up a class, from which one method needs to paint, let’s say, a sun using circles and lines, then how can I have it show up in the main window?

I’ve looked (read: Googled) around, and found that JPanel should be convenient, but painting onto it from another class and method, without knowing what would be their names and when would they use the painting, created… difficulties.

I’m also adding the main method, if that’d be of any use..

static int indez = 0;
    protected static JList list; 
    static boolean valitud = false;
    public static JTextArea txtala;
    public static JScrollPane scrl;
    public static JPanel pilt;
    static Map<Integer, String[]> info = new TreeMap<Integer, String[]>();
    static ArrayList<Integer> nrs = new ArrayList<Integer>();
    public static void main(String[] args){
        Iterator<Entry<Integer, String[]>> iterator;
        Entry<Integer, String[]> entry;
        Integer val = 0;

        JFrame f = new JFrame("Praktikumid");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setSize(750, 350);

        JPanel panel = new JPanel();
        pilt = new JPanel(){public void paintComponent(Graphics g) {
            super.paintComponent(g);
            g.drawString("This is my custom Panel!", 10, 20);
        }};

        pilt.setVisible(false);
        pilt.setPreferredSize(new Dimension(f.getWidth() - 200, f.getHeight() - 20));
        pilt.setBackground(Color.GRAY);

        GroupLayout layout = new GroupLayout(panel);
        panel.setLayout(layout);
        layout.setAutoCreateGaps(true);
        layout.setAutoCreateContainerGaps(true);

        ActionListener kuular = new ActionListener() {
            public void actionPerformed(ActionEvent tegu) {
                valitud = true;
                try {
                    praxStarter();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        };

        MouseListener hiir = new MouseListener() {  
            public void mouseClicked(MouseEvent e) {
                indez = list.getSelectedIndex();
            }
            @Override
            public void mouseEntered(MouseEvent e) {}
            @Override
            public void mouseExited(MouseEvent e) {}
            @Override
            public void mousePressed(MouseEvent e) {}
            @Override
            public void mouseReleased(MouseEvent e) {}  
        };  

        JLabel kiri = new JLabel("Vali hiirega ja vajuta nupule");

        ArrayList<String> selections = new ArrayList<String>();

        // Iterating over all the items in another method to get the modules

        list = new JList(selections.toArray());
        list.setSelectedIndex(0);
        list.addMouseListener(hiir);

        JScrollPane listScroller = new JScrollPane(list, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
        listScroller.setMinimumSize(new Dimension(200, 50));
        listScroller.setMaximumSize(new Dimension(200, f.getHeight() * 1000));

        JButton button = new JButton("Vali");
        button.setActionCommand(Integer.toString(list.getSelectedIndex()));
        button.addActionListener(kuular);

        Font font = new Font("Arial", Font.PLAIN, 12);
        txtala = new JTextArea("<-- Vali sealt");
        txtala.setEditable(false);
        txtala.setMargin(new Insets(5, 8, 0, 0));
        txtala.setFont(font);
        scrl = new JScrollPane(txtala, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
        scrl.setPreferredSize(new Dimension(f.getWidth() - 200, f.getHeight() - 20));

        pilt.setBackground(Color.PINK);
        pilt.setVisible(false);
        pilt.setPreferredSize(new Dimension(f.getWidth() - 200, f.getHeight() - 20));

        GroupLayout.ParallelGroup menu = layout.createParallelGroup();
        GroupLayout.SequentialGroup row = layout.createSequentialGroup();
        GroupLayout.SequentialGroup leftright = layout.createSequentialGroup();
        GroupLayout.ParallelGroup topdown = layout.createParallelGroup();
        GroupLayout.ParallelGroup dbl = layout.createParallelGroup();
        GroupLayout.ParallelGroup dblrow = layout.createParallelGroup();

        menu.addComponent(kiri);
        menu.addComponent(listScroller);
        menu.addComponent(button);
        leftright.addGroup(menu);
        dbl.addComponent(scrl);
        dbl.addComponent(pilt);
        leftright.addGroup(dbl);

        row.addComponent(kiri);
        row.addComponent(listScroller);
        row.addComponent(button);
        topdown.addGroup(row);
        dblrow.addComponent(scrl);
        dblrow.addComponent(pilt);
        topdown.addGroup(dblrow);

        layout.setHorizontalGroup(leftright);
        layout.setVerticalGroup(topdown);

        panel.setComponentZOrder(pilt, 1);
        panel.setComponentZOrder(scrl, 0);

        f.add(panel);
        //f.pack();
        f.setVisible(true);
    }

    public static void praxStarter()  throws Exception{
            // As a note - nrs is the holder for menu indexes
            // info is a Map of those same menu items 
            // And one entry in info is in the form of String[]{name, class.method}
        String[] tekst = new String[2];
        String kls, met;
        Method meetod;

        txtala.setText("");

        tekst = info.get(nrs.get(indez));
        kls = tekst[1].substring(0, tekst[1].indexOf("."));
        met = tekst[1].substring(tekst[1].indexOf(".") + 1, tekst[1].length());

        meetod = Class.forName(kls).getMethod(met);
        meetod.setAccessible(true);
        meetod.invoke(Class.forName(kls).newInstance());
    }

Also, here would be an example of one class drawing (or trying to draw) there:

public class brush extends Applet {
public void paint(Graphics g) {
        int x0 = 150;
        int y0 = 150;
        int r = 100;
        int x, y;
        double t;

        int w = getWidth();
        int h = getHeight();

        x0 = w / 2;
        y0 = h / 2;

        g.setColor(Color.white);
        g.fillRect(0, 0, w, h);

        g.setColor(Color.black);

        for (t = -Math.PI; t < Math.PI; t = t + Math.PI / 16) {
            x = (int) (r * Math.cos(t) + x0);
            y = (int) (r * Math.sin(t) + y0);
            g.drawLine(x0, y0, x, y);
        }
    }
}

Thanks ahead for any answer and advice!

Edit:
Here’s a screenshot:

On the left is regular, print-text-on-screen module. On the right is the text part hidden, and JPanel shown, with the JPanel painted from pilt = new JPanel() part, but without any other succsessful edits outside the main class.

Edit: I’ve tried to draw in multiple ways, trying out solutions searching showed up, e.g.

`txtala.setVisible(false);
scrl.setVisible(false);
pilt.setBorder(BorderFactory.createLineBorder(Color.BLACK));
pilt.setVisible(true);
//bi = new BufferedImage(pilt.getWidth() + 1000, pilt.getHeight() + 1000, BufferedImage.TYPE_INT_ARGB);
Graphics g = pilt.getGraphics();
g.setColor(Color.black);
g.drawLine(0, 0, 1000, 1000);
g.drawString("OLOLOLOLO!", 30, 50);
pilt.paint(g);
pilt.update(g);
//g.dispose();
//repaint();`

Answer 1

Ohkay, so I went the easy way. In stead of using the same pane in the main window, I just crated a new popup and put the frame in that. I know, it’s not the bestest of solutions, but hay, better than nothing. If I manage to figure out a way to do it without a popup, then I’m going to post it here. Until then, good luck y’all!