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Drawing a warning symbol during form validation in Swing

I developed a swing form that checks the records, since the focus is lost from the JTextComponent and if the record is correct, the background turns green. Otherwise, it turns red.

Here is the code: -

import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.text.JTextComponent;



public class Form extends JFrame implements FocusListener{
JTextField fname,lname,phone,email,address;
BufferedImage img;
public static void main(String args[])
{
SwingUtilities.invokeLater(new Runnable(){public void run(){new Form();}});
}

public Form()
{
super("Form with Validation Capability");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(400,300);
setLayout(new GridLayout(5,3));

try {
    img=ImageIO.read(new File("src/warning.png"));
} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

add(new JLabel("First Name :"));
add(fname=new JTextField(20));
add(new JLabel("Last Name :"));
add(lname=new JTextField(20));
add(new JLabel("Phone Number :"));
add(phone=new JTextField(10));
add(new JLabel("Email:"));
add(email=new JTextField(20));
add(new JLabel("Address :"));
add(address=new JTextField(20));

fname.addFocusListener(this);
lname.addFocusListener(this);
phone.addFocusListener(this);
email.addFocusListener(this);
address.addFocusListener(this);

setVisible(true);
}

public void focusGained(FocusEvent e)
{
((JTextComponent) e.getSource()).setBackground(Color.WHITE);
}
public void focusLost(FocusEvent e)
{
if(e.getSource().equals(fname))
{
    validationForText(fname);
}
else if(e.getSource().equals(lname))
{
    validationForText(lname);
}
else if(e.getSource().equals(email))
{
    validationForEmail(email);
}
else if(e.getSource().equals(phone))
{
    validationForNumber(phone);
}
else{
    ((JTextComponent) e.getSource()).setBackground(Color.GREEN);
}
}
public void validationForText(JTextComponent comp)
{
String temp=comp.getText();
if (temp.matches("^[A-Za-z]+$")) {
    comp.setBackground(Color.GREEN);
}
else
    comp.setBackground(Color.RED);
}
public void validationForNumber(JTextComponent comp)
{
String text=comp.getText();
if(text.matches("^[0-9]+$"))
    comp.setBackground(Color.GREEN);
else
    comp.setBackground(Color.RED);
}
public void validationForEmail(JTextComponent comp)
{
String text=comp.getText();
if(text.matches("[^@]+@([^.]+\\.)+[^.]+"))
    comp.setBackground(Color.GREEN);
else
    comp.setBackground(Color.RED);
}

}

Here is the result for my simple application:

enter image description here

Now I also want to draw a warning symbol (buffered image) in the lower left corner of the wrong field. Can someone help me how to do this as I don’t understand where to draw the image. (I would like to do this with JLayeredPane, as I am studying his application, any piece of code will really help).

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source share
1

JLabel ( LayoutManager, ) Swing UIManager.getIcon("OptionPane.warningIcon")

enter image description here

:

JLabel label=new JLabel(UIManager.getIcon("OptionPane.warningIcon"));

. .

UPDATE:

GlassPane ( JLabel ) , JLayeredPane. . RootPanes

:

  • JFrame

  • setSize JFrame. LayoutManager / getPreferredSize(), , setSize pack() JFrame.

  • FocusListener , .

  • FocusAdapter vs FocusListener, Listener i.e MouseListener MouseAdapter. , . , - , , ,

  • super.XXX i.e focusGained(FocusEvent fe),

, , , :

enter image description here

, :

enter image description here

import java.awt.Color;
import java.awt.Component;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.RenderingHints;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.image.BufferedImage;
import java.util.HashMap;
import java.util.Map;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.text.JTextComponent;

/**
 *
 * @author David
 */
public class GlassValidationPane extends JComponent {

    private static JTextField fname, lname, phone, email, address;
    private static GlassValidationPane gvp = new GlassValidationPane();

    public static void main(String args[]) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {

                JFrame f = new JFrame("Form with Validation Capability");
                f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                //f.setResizable(false);
                f.setLayout(new GridLayout(5, 3));

                f.add(new JLabel("First Name :"));
                f.add(fname = new JTextField(20));
                f.add(new JLabel("Last Name :"));
                f.add(lname = new JTextField(20));
                f.add(new JLabel("Phone Number :"));
                f.add(phone = new JTextField(10));
                f.add(new JLabel("Email:"));
                f.add(email = new JTextField(20));
                f.add(new JLabel("Address :"));
                f.add(address = new JTextField(20));

                f.addComponentListener(new ComponentAdapter() {
                    @Override
                    public void componentResized(ComponentEvent ce) {
                        super.componentResized(ce);
                        gvp.refreshLocations();
                    }
                });
                FocusAdapter fl = new FocusAdapter() {
                    @Override
                    public void focusGained(FocusEvent fe) {
                        super.focusGained(fe);
                        ((JTextComponent) fe.getSource()).setBackground(Color.WHITE);
                    }

                    @Override
                    public void focusLost(FocusEvent fe) {
                        super.focusLost(fe);
                        if (fe.getSource().equals(fname)) {
                            validationForText(fname);
                        } else if (fe.getSource().equals(lname)) {
                            validationForText(lname);
                        } else if (fe.getSource().equals(email)) {
                            validationForEmail(email);
                        } else if (fe.getSource().equals(phone)) {
                            validationForNumber(phone);
                        } else {
                            gvp.removeWarningIcon(((Component) fe.getSource()));
                            ((JTextComponent) fe.getSource()).setBackground(Color.GREEN);
                        }
                    }
                };

                fname.addFocusListener(fl);
                lname.addFocusListener(fl);
                phone.addFocusListener(fl);
                email.addFocusListener(fl);
                address.addFocusListener(fl);

                f.setGlassPane(gvp);

                f.pack();
                f.setVisible(true);
                gvp.setVisible(true);
            }

            public void validationForText(JTextComponent comp) {
                String temp = comp.getText();
                if (temp.matches("^[A-Za-z]+$")) {
                    setGreen(comp);
                } else {
                    setRed(comp);
                }
            }

            public void validationForNumber(JTextComponent comp) {
                String text = comp.getText();
                if (text.matches("^[0-9]+$")) {
                    setGreen(comp);
                } else {
                    setRed(comp);
                }
            }

            public void validationForEmail(JTextComponent comp) {
                String text = comp.getText();
                if (text.matches("[^@]+@([^.]+\\.)+[^.]+")) {
                    setGreen(comp);
                } else {
                    setRed(comp);
                }
            }

            private void setRed(JTextComponent comp) {
                comp.setBackground(Color.RED);
                gvp.showWarningIcon(comp);
            }

            private void setGreen(JTextComponent comp) {
                comp.setBackground(Color.GREEN);
                gvp.removeWarningIcon(comp);

            }
        });
    }
    private HashMap<Component, JLabel> warningLabels = new HashMap<>();
    private ImageIcon warningIcon;

    public GlassValidationPane() {
        setLayout(null);//this is the exception to the rule case a layoutmanager might make setting Jlabel co-ords harder
        setOpaque(false);
        Icon icon = UIManager.getIcon("OptionPane.warningIcon");
        int imgW = icon.getIconWidth();
        int imgH = icon.getIconHeight();
        BufferedImage img = ImageUtilities.getBufferedImageOfIcon(icon, imgW, imgH);
        warningIcon = new ImageIcon(ImageUtilities.resize(img, 24, 24));
    }

    void showWarningIcon(Component c) {
        if (warningLabels.containsKey(c)) {
            return;
        }

        JLabel label = new JLabel();
        label.setIcon(warningIcon);

        //int x=c.getX();//this will make it insode the component
        int x = c.getWidth() - label.getIcon().getIconWidth();//this makes it appear outside/next to component
        int y = c.getY();

        label.setBounds(x, y, label.getIcon().getIconWidth(), label.getIcon().getIconHeight());
        add(label);
        label.setVisible(true);
        revalidate();
        repaint();
        warningLabels.put(c, label);
    }

    public void removeWarningIcon(Component c) {
        for (Map.Entry<Component, JLabel> entry : warningLabels.entrySet()) {
            Component component = entry.getKey();
            JLabel jLabel = entry.getValue();
            if (component == c) {
                remove(jLabel);
                revalidate();
                repaint();
                break;
            }
        }
        warningLabels.remove(c);
    }

    public void refreshLocations() {
        for (Map.Entry<Component, JLabel> entry : warningLabels.entrySet()) {
            Component c = entry.getKey();
            JLabel label = entry.getValue();
            //int x=c.getX();//this will make it insode the component
            int x = c.getWidth() - label.getIcon().getIconWidth();//this makes it appear outside/next to component
            int y = c.getY();

            label.setBounds(x, y, label.getIcon().getIconWidth(), label.getIcon().getIconHeight());
            revalidate();
            repaint();
        }
    }
}

class ImageUtilities {

    public static BufferedImage resize(BufferedImage image, int width, int height) {
        BufferedImage bi = new BufferedImage(width, height, BufferedImage.TRANSLUCENT);
        Graphics2D g2d = (Graphics2D) bi.createGraphics();
        g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
        g2d.drawImage(image, 0, 0, width, height, null);
        g2d.dispose();
        return bi;
    }

    public static BufferedImage getBufferedImageOfIcon(Icon icon, int imgW, int imgH) {
        BufferedImage img = new BufferedImage(imgW, imgH, BufferedImage.TYPE_INT_ARGB);
        Graphics2D g2d = (Graphics2D) img.getGraphics();
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        icon.paintIcon(null, g2d, 0, 0);
        g2d.dispose();
        return img;
    }
}
+8

Source: https://habr.com/ru/post/1541874/

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