Question

I’m relatively new to GUI building.

I want to make a GUI with a button(that I already have) that a user can press and select an image and then dynamically, this image to be loaded in the GUI in a panel.
I want the image to change dynamically every time the user browses an image.

So far my code is that …. But I cant connect the button to a JPanel or something.

import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.swing.*;

public class WebAppImg extends javax.swing.JFrame {
    private int image_height;
    private int image_aspect_ratio;
    private Graphics2D engine;
    private JLabel photoComponent;    

    /**
     * Creates new form WebAppImg
     */
    public WebAppImg() {
        initComponents();
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jButton1 = new javax.swing.JButton();
        jTextField1 = new javax.swing.JTextField();
        jLabel1 = new javax.swing.JLabel();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setPreferredSize(new java.awt.Dimension(600, 480));

        jButton1.setText("Attach");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jTextField1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jTextField1ActionPerformed(evt);
            }
        });

        jLabel1.setText("label2");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(21, 21, 21)
                .addComponent(jButton1)
                .addGap(154, 154, 154)
                .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 239, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addContainerGap(133, Short.MAX_VALUE))
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 199, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(120, 120, 120))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addGap(57, 57, 57)
                .addComponent(jLabel1, javax.swing.GroupLayout.PREFERRED_SIZE, 163, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 141, Short.MAX_VALUE)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton1)
                    .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addGap(35, 35, 35))
        );

        pack();
    }// </editor-fold>

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
        JFileChooser chooser = new JFileChooser();
        JLabel label2 = new JLabel();
        JInternalFrame jInternalFrame1 = new JInternalFrame();
        chooser.showOpenDialog(null);
        File f = chooser.getSelectedFile();
        String filename = f.getAbsolutePath();
        jTextField1.setText(filename);
        jInternalFrame1.getDesktopIcon();
    }

    private void jTextField1ActionPerformed(java.awt.event.ActionEvent evt) {
        // TODO add your handling code here:
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(WebAppImg.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(WebAppImg.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(WebAppImg.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(WebAppImg.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new WebAppImg().setVisible(true);
            }
        });
        //Create a file chooser

    }
    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JTextField jTextField1;
    // End of variables declaration
}

Answer 1

I think what you want is the chosen image to be shown, if so change you jButton1ActionPerformed method to this:

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
    JFileChooser chooser = new JFileChooser();
    chooser.showOpenDialog(null);
    File f = chooser.getSelectedFile();
    String filename = f.getAbsolutePath();
    jTextField1.setText(filename);
    try {
        ImageIcon ii=new ImageIcon(scaleImage(120, 120, ImageIO.read(new File(f.getAbsolutePath()))));//get the image from file chooser and scale it to match JLabel size
        jLabel1.setIcon(ii);
    } catch (Exception ex) {
        ex.printStackTrace();
    }
}

public static BufferedImage scaleImage(int w, int h, BufferedImage img) throws Exception {
    BufferedImage bi;
    bi = new BufferedImage(w, h, BufferedImage.TRANSLUCENT);
    Graphics2D g2d = (Graphics2D) bi.createGraphics();
    g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
    g2d.drawImage(img, 0, 0, w, h, null);
    g2d.dispose();
    return bi;
}

an even better solution would see you using a SwingWorker to load the image so UI doesnt become unresponsive (if the image is large):

private ImageIcon ii;

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
    JFileChooser chooser = new JFileChooser();
    chooser.showOpenDialog(null);
    final File f = chooser.getSelectedFile();
    String filename = f.getAbsolutePath();
    if (f == null) {
        return;
    }
    jTextField1.setText(filename);

    SwingWorker sw = new SwingWorker() {
        @Override
        protected Object doInBackground() throws Exception {
            Thread.sleep(5000);//simulate large image takes long to load
            ii = new ImageIcon(scaleImage(120, 120, ImageIO.read(new File(f.getAbsolutePath()))));
            return null;
        }

        @Override
        protected void done() { 
            super.done();
            jLabel1.setIcon(ii);
        }
    };
    sw.execute();

}