Animation Constructor not working in Java GUI

Question

Hello I am new to Java GUI I made a second.java which is as below:

package theproject;
import java.awt.event.*;
import java.awt.*;

import javax.swing.*;

public class second extends JPanel implements ActionListener {
private Timer animator;
private ImageIcon imageArray[];
private int delay=50, totalFrames=8, currentFreames=1;

public second()
{
  imageArray= new ImageIcon[totalFrames];
  System.out.println(imageArray.length);
  for(int i=0; i<imageArray.length;i++)
  {
      imageArray[i]=new ImageIcon(i+1+".png");
      System.out.println(i+1);

  }
  animator= new Timer(delay, this);
  animator.start();

   }

  public void paintComponent(Graphics g )
  {
  super.paintComponent(g);
   if(currentFreames<8)
   {

  imageArray[currentFreames].paintIcon(this, g, 0, 0);
  currentFreames++;
  System.out.println(currentFreames);
}
else{
    currentFreames=0;
}
  }

@Override
public void actionPerformed(ActionEvent arg0) {

    repaint();
}

 }

And a Gui calling the constructor second and output is not showing . Can you please guide me what should I do and the gui is given below:

   package theproject;

 import java.awt.EventQueue;

 import javax.swing.JFrame;
 import javax.swing.JButton;
 import java.awt.BorderLayout;
 import java.awt.event.ActionListener;
 import java.awt.event.ActionEvent;
 import javax.swing.SwingConstants;
 import javax.swing.JTextField;

  public class Sav {

private JFrame frame;
private JTextField textField;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                Sav window = new Sav();
                window.frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the application.
 */
public Sav() {
    initialize();
}

/**
 * Initialize the contents of the frame.
 */
private void initialize() {
    frame = new JFrame();
    frame.setBounds(100, 100, 450, 300);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.getContentPane().setLayout(null);

    textField = new JTextField();
    textField.setBounds(10, 0, 261, 20);
    frame.getContentPane().add(textField);
    textField.setColumns(10);

    JButton btnNewButton = new JButton("Submit");
    btnNewButton.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
        second s= new second();
         frame.add(s);
        }
    });
    btnNewButton.setBounds(273, -1, 89, 23);
    frame.getContentPane().add(btnNewButton);

}
}

The gui has to basically call the constructor and which will showcase the animation on the screen If someone what i am doing wrong or if something that has to be done please let me know .

Answer 1

First, don't update the state within the paintComponent method, paint can occur for a number of reasons at any time, mostly without your interaction. Painting should simple paint the current state. In your ActionListener, you should advance the frame and make decisions about what should occur (like resetting the frame value)

Second, you never actually add second to anything, so it will never be displayed.

Third, you don't override getPreferredSize in second, so the layout managers will have no idea what size the component should be and will simply be assigned 0x0, making it as good as invisible as makes no difference

Fourth, you're using null layouts. This is going to make you life impossibly hard. Swing has been designed and optimised around the use of layout managers, they do important work in deciding how best to deal with differences in font metrics across different rendering systems/pipelines, I highly recommend that you take the time to learn how to use them

Fifthly, paintComponent has no business been public, no one should ever call it directly

Example

import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.Timer;

public class Sav {

    private JFrame frame;
    private JTextField textField;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    Sav window = new Sav();
                    window.frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the application.
     */
    public Sav() {
        initialize();
    }

    /**
     * Initialize the contents of the frame.
     */
    private void initialize() {
        frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().setLayout(new GridBagLayout());
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.gridwidth = GridBagConstraints.REMAINDER;

        textField = new JTextField(20);
        frame.getContentPane().add(textField, gbc);

        JButton btnNewButton = new JButton("Submit");
        btnNewButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                second s = new second();
                frame.add(s, gbc);
                frame.getContentPane().revalidate();
                frame.pack();
                frame.setLocationRelativeTo(null);
            }
        });
        frame.getContentPane().add(btnNewButton, gbc);

        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public class second extends JPanel implements ActionListener {

        private Timer animator;
        private ImageIcon imageArray[];
        private int delay = 50, totalFrames = 8, currentFreames = 1;

        public second() {
            imageArray = new ImageIcon[totalFrames];
            for (int i = 0; i < imageArray.length; i++) {
                imageArray[i] = new ImageIcon(getImage(i));

            }
            animator = new Timer(delay, this);
            animator.start();

        }

        protected Image getImage(int index) {
            BufferedImage img = new BufferedImage(1, 1, BufferedImage.TYPE_INT_ARGB);
            Graphics2D g2d = img.createGraphics();
            FontMetrics fm = g2d.getFontMetrics();
            g2d.dispose();
            String text = Integer.toString(index);
            int height = fm.getHeight();
            int width = fm.stringWidth(text);

            img = new BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
            g2d = img.createGraphics();
            g2d.setColor(getForeground());
            g2d.drawString(text, 0, fm.getAscent());
            g2d.dispose();
            return img;
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(imageArray[0].getIconWidth(), imageArray[1].getIconHeight());
        }

        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            imageArray[currentFreames].paintIcon(this, g, 0, 0);
        }

        @Override
        public void actionPerformed(ActionEvent arg0) {
            currentFreames++;
            if (currentFreames >= imageArray.length) {
                currentFreames = 0;
            }
            repaint();
        }

    }
}

Your code is also not working. It increment the values of image set but do not displays the images

Works just fine for me...

imageArray[i]=new ImageIcon(i+1+".png"); will not generate any errors if the image can't be loaded for some reason (and it will load the images in the background thread, which is just another issue).

Instead, I would recommend using ImageIO.read instead, which will throw a IOException if the image can't be read for some reason, which is infinitely more useful. See Reading/Loading an Image for more details