High CPU usage in Custom JPasswordField

Question

I have created a custom PasswordField extending JPasswordField. And It is working fine. But the problem is when I use this passwordfield and run the JFrame, this consumes HIGH CPU Usage. I only add this component and run it. But when I use another component like JButton or TextField It works fine and CPU usage is normal. So I need to know how to fix that problem or whether there is a problem in my code that eats CPU. Can anybody help me? Thanks in advance.

Here is the code,

public class PasswordField extends JPasswordField implements ComponentListener
{
    private boolean materialMode = false;
    private Color borderColorNoFocus = MaterialColor.GREY_300;
    private Color borderColorFocus = new Color(0, 112, 192);
    private Dimension d = new Dimension(250, 42);
    private String placeholder = "";
    private Color phColor = new Color(0, 112, 192);
    private boolean band = true;
    private final JButton button = new JButton();
    private ImageIcon iconBlack = new ImageIcon(getClass().getResource("/Library/Images/visibleBlack.png"));
    private ImageIcon iconWhite = new ImageIcon(getClass().getResource("/Library/Images/visibleWhite.png"));
    private boolean xBlackIcon = false;
    private int btnHeight = this.d.height - 10;
    private boolean txtVisible = false;

    public PasswordField()
    {
        this.setEchoChar('*');
        this.setSize(this.d);
        this.setPreferredSize(this.d);
        this.setVisible(true);
        this.setMargin(new Insets(3, 6, 3, 6));

        this.setFont(Roboto.BOLD.deriveFont(14.0F));
        this.setForeground(new Color(0, 112, 192));
        this.button.setText("");
        this.button.setBorderPainted(false);
        this.button.setContentAreaFilled(false);
        this.button.setMargin(new Insets(2, 2, 2, 2));
        this.button.setVisible(true);
        this.button.setFocusPainted(false);
        this.button.setCursor(new Cursor(12));
        this.button.setBackground(new Color(0, 112, 192));
        this.add(this.button);
        this.setVisible(true);
        this.addComponentListener(this);
        this.setSelectionColor(this.button.getBackground());
        updateButton();

        this.getDocument().addDocumentListener(new DocumentListener()
        {
            @Override
            public void removeUpdate(DocumentEvent e)
            {
                PasswordField.this.band = (PasswordField.this.getText().length() <= 0);
            }

            @Override
            public void insertUpdate(DocumentEvent e)
            {
                PasswordField.this.band = false;
            }

            @Override
            public void changedUpdate(DocumentEvent de) {}
        });

        this.button.addMouseListener(new MouseListener()
        {
            @Override
            public void mouseClicked(MouseEvent e)
            {
                if (PasswordField.this.txtVisible)
                {
                    ((JPasswordField)PasswordField.this.button.getParent()).setEchoChar('*');
                    PasswordField.this.iconBlack = new ImageIcon(getClass().getResource("/Library/Images/visibleBlack.png"));
                    PasswordField.this.iconWhite = new ImageIcon(getClass().getResource("/Library/Images/visibleWhite.png"));
                    PasswordField.this.txtVisible = false;
                }
                else
                {
                    ((JPasswordField)PasswordField.this.button.getParent()).setEchoChar('\000');
                    PasswordField.this.iconBlack = new ImageIcon(getClass().getResource("/Library/Images/invisibleBlack.png"));
                    PasswordField.this.iconWhite = new ImageIcon(getClass().getResource("/Library/Images/invisibleWhite.png"));
                    PasswordField.this.txtVisible = true;
                }
        ((JPasswordField)PasswordField.this.button.getParent()).requestFocus();
            }

            @Override
            public void mousePressed(MouseEvent e) {}

            @Override
            public void mouseReleased(MouseEvent e) {}

            @Override
            public void mouseEntered(MouseEvent e)
            {
                PasswordField.this.button.setOpaque(true);
                PasswordField.this.button.setIcon(PasswordField.this.xBlackIcon ? PasswordField.this.iconBlack : PasswordField.this.iconWhite);
            }

            @Override
            public void mouseExited(MouseEvent e)
            {
                PasswordField.this.button.setOpaque(false);
                PasswordField.this.button.setIcon(null);
            }
        });
        this.setPlaceholder("Password Field");
    }

    public boolean isxDarkIcon()
    {
        return this.xBlackIcon;
    }

    public void setxDarkIcon(boolean xDarkIcon)
    {
        this.xBlackIcon = xDarkIcon;
    }

    public Color getBotonColor()
    {
        return this.button.getBackground();
    }

    public void setBotonColor(Color botonColor)
    {
        this.button.setBackground(botonColor);
        setSelectionColor(this.button.getBackground());
    }

    public Color getBorderColorFocus()
    {
        return this.borderColorFocus;
    }

    public void setBorderColorFocus(Color borderColorFocus)
    {
        this.borderColorFocus = borderColorFocus;
    }

    public Color getBorderColorNoFocus()
    {
        return this.borderColorNoFocus;
    }

    public void setBorderColorNoFocus(Color borderColorNoFocus)
    {
        this.borderColorNoFocus = borderColorNoFocus;
    }

    public boolean isMaterialMode()
    {
        return this.materialMode;
    }

    public void setMaterialMode(boolean materialMode)
    {
        this.materialMode = materialMode;
    }

    private void updateBorder()
    {
        Border border = BorderFactory.createMatteBorder(0, 0, 2, 0, this.borderColorFocus);
        setBorder(BorderFactory.createCompoundBorder(border, 
                BorderFactory.createEmptyBorder(10, 10, 10, this.button.getSize().width + 5)));
    }

    private void updateButton()
    {
        this.btnHeight = (getSize().height - 10);
        this.button.setSize(new Dimension(this.btnHeight, this.btnHeight));
        this.button.setPreferredSize(new Dimension(this.btnHeight, this.btnHeight));

        this.button.setLocation(getWidth() - this.button.getWidth() - 5, 5);
        updateBorder();
    }

    @Override
    public void componentResized(ComponentEvent e)
    {
        updateButton();
    }

    @Override
    public void componentMoved(ComponentEvent e) {}

    @Override
    public void componentShown(ComponentEvent e) {}

    @Override
    public void componentHidden(ComponentEvent e) {}

    public void setPlaceholder(String placeholder)
    {
        this.placeholder = placeholder;
    }

    public String getPlaceholder()
    {
        return this.placeholder;
    }

    @Override
    public void paintComponent(Graphics g)
    {
        super.paintComponent(g);
        if (isMaterialMode())
        {
            if (isFocusOwner())
            {
                Border border = BorderFactory.createMatteBorder(0, 0, 2, 0, this.borderColorFocus);
                setBorder(BorderFactory.createCompoundBorder(border, 
                        BorderFactory.createEmptyBorder(10, 10, 10, this.button.getSize().width + 5)));

                this.phColor = getForeground();
            }
            else
            {
                Border border = BorderFactory.createMatteBorder(0, 0, 2, 0, this.borderColorNoFocus);
                setBorder(BorderFactory.createCompoundBorder(border, 
                        BorderFactory.createEmptyBorder(10, 10, 10, this.button.getSize().width + 5)));

                this.phColor = this.borderColorNoFocus;
            }
        }
        else
        {
            Border border = BorderFactory.createMatteBorder(0, 0, 2, 0, this.borderColorFocus);
            setBorder(BorderFactory.createCompoundBorder(border, 
                    BorderFactory.createEmptyBorder(10, 10, 10, this.button.getSize().width + 5)));
            this.phColor = getForeground();
        }

        g.setColor(new Color(this.phColor.getRed(), this.phColor.getGreen(), this.phColor.getBlue(), 90));

        g.drawString(this.band ? this.placeholder : "", 
        getMargin().left, 
        getSize().height / 2 + getFont().getSize() / 2);
    }
}

Answer 1

I have reproduced your java code on my machine and debugged it.
I found out why your code causes High CPU.

You used the setBorder() method within your paintComponent() method and that's false, because if you look into the setBorder() method in your parents class, you will see that this method always calls repaint() if the border has been changed. (And that's quite normal)

So if you call in your paint() method something which calls repaint() then you will be in a endless loop.

paint() -> repaint() -> paint() -> repaint() -> paint().....

And in your code you used setBorder 3 times.

You can solve this problem if you outsource your setBorder code and call it from elsewhere.