CODEWITHSUNDEEP
javaswingjpanelpaintcomponentkeylistener
ez pz lmn sqz
ez pz lmn sqz

Reputation: 15

Lag Issues With Moving A Circle

So I was making a game for my Computer Science class, pretty much making a modified version of the game Frogger, and I first started off by just moving a circle across the JPanel to mimic the frogs movement and I realized a very annoying lag between the interactions with the buttons. Does anyone know how to completely get rid of the lag or perhaps reduce it? Any tips or help would be much appreciated! Here is the code so far for just the circle movement and if you see any improvements that could be done, please feel free to leave your comments.

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;

public class second extends JPanel implements ActionListener, KeyListener 
{
Timer t = new Timer (5, this);
double x = 0, y = 0, velx = 0, vely = 0;

public second()
{
    t.start();
    addKeyListener(this);
    setFocusable(true);
    setFocusTraversalKeysEnabled(false);
}

public void paintComponent (Graphics g)
{
    super.paintComponent(g);
    Graphics2D g2 = (Graphics2D) g;
    g2.fill(new Ellipse2D.Double(x, y, 10, 10));
}

public void actionPerformed (ActionEvent e)
{
    repaint();
    x += velx;
    y += vely;
}

public void up()
{
    vely = -5;
    velx = 0;
}

public void down()
{
    vely = 5;
    velx = 0;
}

public void left()
{
    velx = -5;
    vely = 0;
}

public void right()
{
    velx = 5;
    vely = 0;
}

public void upEnd()
{
    velx = 0;
    vely = 0;
}

public void downEnd()
{
    velx = 0;
    vely = 0;
}

public void leftEnd()
{
    velx = 0;
    vely = 0;
}

public void rightEnd()
{
    velx = 0;
    vely = 0;
}

public void keyPressed (KeyEvent e)
{
    int code = e.getKeyCode();
    if (code == KeyEvent.VK_UP)
    {
        up();
    }
    if (code == KeyEvent.VK_DOWN)
    {
        down();
    }
    if (code == KeyEvent.VK_RIGHT)
    {
        right();
    }
    if (code == KeyEvent.VK_LEFT)
    {
        left();
    }
}

public void keyTyped (KeyEvent e) {}

public void keyReleased (KeyEvent e) 
{
    int code = e.getKeyCode();
    if (code == KeyEvent.VK_UP)
    {
        upEnd();
    }
    if (code == KeyEvent.VK_DOWN)
    {
        downEnd();
    }
    if (code == KeyEvent.VK_RIGHT)
    {
        rightEnd();
    }
    if (code == KeyEvent.VK_LEFT)
    {
        leftEnd();
    }
}
}

And here is the Main file:

import javax.swing.JFrame;

public class Macheads
{
public static void main (String[] args)
{
    JFrame f = new JFrame();
    second s = new second();
    f.add(s);
    f.setVisible(true);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setSize(800,600);
}
}

Upvotes: 1

Views: 134

Answers (2)

camickr
camickr

Reputation: 324128

Don't use a KeyListener. Instead you should be using Key Bindings.

The keyboard has a delay for repeating events. Use a Swing Timer to schedule the animation instead of relying on key events to be generated. See Motion Using the Keyboard for more information and examples.

Upvotes: 1

user1959349
user1959349

Reputation:

Try using only the keyListener without the timer and actionlistener.

public void keyPressed (KeyEvent e)
{
    int code = e.getKeyCode();
    if (code == KeyEvent.VK_UP)
    {
        up();
    }
    if (code == KeyEvent.VK_DOWN)
    {
        down();
    }
    if (code == KeyEvent.VK_RIGHT)
    {
        right();
    }
    if (code == KeyEvent.VK_LEFT)
    {
        left();
    }
     x += velx;
     y += vely;
    repaint(); //added and will repaint everytime key is pressed
}

//no need to place arguments in keyTyped and keyReleased because JPanel is repainted on keypressed...

Upvotes: 0

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