Develop Reference

Drawing rectangle within the loop?

I'm trying to animate a rectangle based on a coordinate determined by for-loop, inside a button. Here is my JComponent Class:
public class Rect extends JComponent {
public int x;
public int y;
public int w;
public int h;
public Rect (int x, int y, int w, int h) {
this.x = x;
this.y = y;
this.w = w;
this.h = h;
repaint();
}
#Override
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
super.paintComponent(g);
g2.setColor(Color.green);
g2.drawRect(x+15, y+15, w, h);
}
}
and here is my button and button inside JFrame class:
public class MainFrame extends JFrame {
Rect R = new Rect(15, 15, 50, 50);
JPanel lm = new JPanel();
LayoutManager lay = new OverlayLayout(lm);
JButton animate = new JButton("animate");
public MainFrame () {
setSize(1200, 700);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
lm.setLayout(lay);
lm.add(R);
}
animate.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
for (int k = 0; k < 500; k+=50) {
R = new Rect(k, k, 50, 50);
validate();
repaint();
}
}
});
}
But when I run the code and click the button, nothing happens. What's wrong?
EDIT: I run the frame inside my main class like this:
public class OrImage {
public static void main(String[] args) throws Exception
SwingUtilities.invokeLater(new Runnable() {
public void run() {
MainFrame mf = new MainFrame();
mf.setVisible(true);
}
});
}
}

I changed the code of class MainFrame such that when you press the animate button, something happens, but I don't know if that is what you want to happen.
I did not change class Rect and I added main() method to MainFrame just to keep everything in one class.
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.LayoutManager;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.OverlayLayout;
public class MainFrame extends JFrame {
Rect R = new Rect(15, 15, 50, 50);
JPanel lm = new JPanel();
LayoutManager lay = new OverlayLayout(lm);
JButton animate = new JButton("animate");
public MainFrame () {
setSize(1200, 700);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
lm.setLayout(lay);
lm.add(R);
animate.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
for (int k = 0; k < 500; k+=50) {
R = new Rect(k, k, 50, 50);
lm.add(R);
}
lm.revalidate();
lm.repaint();
}
});
add(lm, BorderLayout.CENTER);
add(animate, BorderLayout.PAGE_END);
setLocationByPlatform(true);
setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> new MainFrame());
}
}
The main change is in method actionPerformed(). You need to add R to the JPanel. You need to call revalidate() on the JPanel because you have changed the number of components that it contains. And after calling revalidate() you should call repaint() (again, on the JPanel) to make it redraw itself.
This is how it looks before pressing animate.
And this is how it looks after pressing animate
EDIT
As requested – with animation.
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.LayoutManager;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.OverlayLayout;
import javax.swing.Timer;
public class MainFrame extends JFrame {
Rect R = new Rect(15, 15, 50, 50);
JPanel lm = new JPanel();
LayoutManager lay = new OverlayLayout(lm);
JButton animate = new JButton("animate");
private int x;
private int y;
private Timer timer;
public MainFrame () {
setSize(1200, 700);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
lm.setLayout(lay);
lm.add(R);
timer = new Timer(500, event -> {
if (x < 500) {
lm.remove(R);
x += 50;
y += 50;
R = new Rect(x, y, 50, 50);
lm.add(R);
lm.revalidate();
lm.repaint();
}
else {
timer.stop();
}
});
timer.setInitialDelay(0);
animate.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
timer.start();
}
});
add(lm, BorderLayout.CENTER);
add(animate, BorderLayout.PAGE_END);
setLocationByPlatform(true);
setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(() -> new MainFrame());
}
}

Problem with Java GridLayout and adding Buttons

I want to add 100 buttons into an GridLayout and my code works but sometimes it only adds one button and if I click where the other buttons belong the button where I clicked appears.
it happens totally randomly and I don't get it.
Here is my code:
public class GamePanel extends JPanel {
GameUI controler;
GridLayout gameLayout = new GridLayout(10,10);
JButton gameButtons[] = new JButton[100];
ImageIcon ice;
JButton startButton;
JButton exitButton;
ImageIcon startIcon;
ImageIcon exitIcon;
URL urlIcon;
private int i;
public GamePanel(GameUI controler) {
this.setLayout(gameLayout);
this.controler = controler;
urlIcon = this.getClass().getResource("/icons/Overlay.png");
ice = new ImageIcon(urlIcon);
makeButtons();
}
#Override
public void paint(Graphics g) {
super.paint(g);
}
public void makeButtons() {
for(i = 0; i< 100; i++) {
gameButtons[i] = new JButton(ice);
this.add(gameButtons[i]);
revalidate();
}
repaint();
}
}
update:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.lang.reflect.InvocationTargetException;
import java.net.URL;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.net.URL;
public class GameUI extends JFrame {
ImageIcon i;
Image jFrameBackground;
JButton startButton;
JButton exitButton;
ImageIcon startIcon;
ImageIcon exitIcon;
public GameUI() {
setResizable(false);
this.setSize(1200, 800);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setLayout(null);
BackGroundPanel backGroundPanel = new BackGroundPanel();
GamePanel panel = new GamePanel(this);
ButtonPanel buttonPanel = new ButtonPanel();
panel.setSize(500,500);
panel.setLocation(100, 150);
backGroundPanel.setSize(this.getWidth(),this.getHeight());
backGroundPanel.setLocation(0,0);
buttonPanel.setSize(390,50);
buttonPanel.setLocation(100,100);
this.add(backGroundPanel);
this.add(panel);
this.add(buttonPanel);
backGroundPanel.setBackground(Color.BLACK);
}
public static void main(String[] args) throws InvocationTargetException, InterruptedException {
javax.swing.SwingUtilities.invokeAndWait(
new Runnable(){
#Override
public void run() {
GameUI ui = new GameUI();
ui.setVisible(true);
}
}
);
}
}

As I mentioned in comments, you're using a null layout, and this is the source of your problems.
You're using the null layout to try to layer JPanels, one on top of the other, and that is not how it should be used or what it is for, nor how you should create backgrounds. This is having the effect of the background covering your buttons until your mouse hovers over them.
Instead if you wish to create a background image, I would recommend that you:
create a JPanel, say called BackgroundPanel,
override its paintComponent method,
call its super.paintComponent(g); on your method's first line
then draw the image it should display
then give it a decent layout manager
and add your GUI components to it
Make sure that any JPanels added to it are made transparent via .setOpaque(false)
Other options include using a JLayeredPane, but you really don't need this just to have a background.
For example, the following code produces:
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.*;
public class GameUI2 {
private static final String IMG_PATH = "https://upload.wikimedia.org/wikipedia/commons/3/3f/"
+ "Butterfly_Nebula_in_narrow_band_Sulfur%2C_Hydrogen_and_Oxygen_Stephan_Hamel.jpg";
private static final String BTN_IMG_PATH = "https://upload.wikimedia.org/wikipedia/commons/5/54/Crystal_Project_Games_kids.png";
private static void createAndShowGui() {
BufferedImage bgImg = null;
BufferedImage btnImg = null;
try {
URL bgImgUrl = new URL(IMG_PATH);
URL btnImgUrl = new URL(BTN_IMG_PATH);
bgImg = ImageIO.read(bgImgUrl);
btnImg = ImageIO.read(btnImgUrl);
} catch (IOException e) {
e.printStackTrace();
System.exit(-1);
}
BackgroundPanel2 mainPanel = new BackgroundPanel2(bgImg);
mainPanel.setLayout(new GridBagLayout());
GamePanel2 gamePanel = new GamePanel2(btnImg);
mainPanel.add(gamePanel);
JFrame frame = new JFrame("Game");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.setResizable(false);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
}
#SuppressWarnings("serial")
class BackgroundPanel2 extends JPanel {
private Image backgroundImg;
public BackgroundPanel2(Image backgroundImg) {
this.backgroundImg = backgroundImg;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (backgroundImg != null) {
g.drawImage(backgroundImg, 0, 0, this);
}
}
#Override
public Dimension getPreferredSize() {
if (isPreferredSizeSet() || backgroundImg == null) {
return super.getPreferredSize();
} else {
int w = backgroundImg.getWidth(this);
int h = backgroundImg.getHeight(this);
return new Dimension(w, h);
}
}
}
#SuppressWarnings("serial")
class GamePanel2 extends JPanel {
public static final int MAX_BUTTONS = 100;
private static final int IMG_WIDTH = 40;
JButton[] gameButtons = new JButton[MAX_BUTTONS];
public GamePanel2(Image buttonImg) {
setOpaque(false);
if (buttonImg.getWidth(this) > IMG_WIDTH) {
buttonImg = buttonImg.getScaledInstance(IMG_WIDTH, IMG_WIDTH, Image.SCALE_SMOOTH);
}
Icon icon = new ImageIcon(buttonImg);
setLayout(new GridLayout(10, 10, 4, 4));
for (int i = 0; i < gameButtons.length; i++) {
int finalIndex = i;
JButton btn = new JButton(icon);
btn.addActionListener(e -> {
String text = String.format("Button: %02d", finalIndex);
System.out.println(text);
});
add(btn);
gameButtons[i] = btn;
}
}
}

How to turn any moving object?

I am simply making an aquarium. Right now, I have only one fish inside it. It is moving forward and when it hits the frame it again moves back. But the face of the fish is still facing towards right side. When it moves back, I want it's face to change. How can I do that? Here is my code.
package aquarium;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.util.Random;
import javax.swing.Timer;
public class Aquarium extends JPanel implements ActionListener{
Random r = new Random();
Timer t = new Timer(5, this);
int x = 0, y= 30;
int velX = 1 ,velY =1;
private ImageIcon fish2image;
private ImageIcon fish1image;
ImageIcon image = new ImageIcon(getClass().getResource("../res/aquarium.gif"));
ImageIcon image1 = new ImageIcon(getClass().getResource("../res/smallFish.gif"));
int numberFish = 12;
Aquarium(){
}
#Override
public void paintComponent(Graphics g){
super.paintComponent(g);
image.paintIcon(this, g, 0, 0);
image1.paintIcon(this, g, x, y);
t.start();
}
#Override
public void actionPerformed(ActionEvent e){
if(x<0 || x>465){
velX = -velX;
}
x += velX;
repaint();
}
public static void main(String[] args) {
Aquarium a = new Aquarium();
JFrame f = new JFrame();
f.setTitle("The Aquarium");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
f.setResizable(false);
f.setBounds(500,200,500,300); //left,top,width,height
f.add(a);
}
}

KeyListener not working with JPanel

I am trying to make a menu class for a small game I'm making, and it all works fine, except now, the KeyListener does not work at all, I tried applying it to JFrame and JPanel, but nothing is working...
Here is my MainClass:
package bombermangame;
import javax.swing.JFrame;
public class MainClass {
public static int WIDTH = 870, HEIGHT = 800;
public static JFrame frame = new JFrame();
public static Menu menu = new Menu();
public static void main(String[] args) {
frame.setContentPane(menu);
frame.pack();
frame.setResizable(false);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("BomberMan V0.3");
frame.setSize(WIDTH, HEIGHT);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
`
And here is my Menu class:
package bombermangame;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Timer;
import java.util.TimerTask;
import javax.swing.JButton;
import javax.swing.JPanel;
public class Menu extends JPanel implements ActionListener {
private static final long serialVersionUID = 1L;
private JButton startButton = new JButton("Play");
private int x = 0, y = 500;
private boolean down = false;
private boolean up = true;
private Timer timer = new Timer();
public Menu() {
setBackground(Color.blue);
startButton = new JButton("Start");
startButton.setBounds(0,0, 100, 40);
startButton.setPreferredSize(new Dimension(100, 40));
startButton.addActionListener(this);
startButton.setFocusPainted(true);
add(startButton);
}
public void actionPerformed(ActionEvent ae) {
Object a = ae.getSource();
Game game = new Game();
Listener keys = new Listener();
if (a == startButton) {
timer.cancel();
MainClass.frame.remove(MainClass.menu);
MainClass.frame.setContentPane(game);
MainClass.frame.addKeyListener(keys);
game.addKeyListener(keys);
game.setBackground(Color.BLACK);
game.setDoubleBuffered(true);
game.setBounds(0, 0, WIDTH, HEIGHT);
Game.running = true;
}
}
}

Why is my JPanel or JFrame not appearing?

I am making a game. There are 3 different files in the project, there is a file called Dude, Frame and Board. So can anyone help me? The code:
The code for Board:
package Ourgame;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Board extends JPanel implements ActionListener{
Dude p;
Image img;
Timer time;
public Board() {
p = new Dude();
addKeyListener(new AL());
setFocusable(true);
ImageIcon i = new ImageIcon("/Users/appleuser/Desktop");
img = i.getImage();
time = new Timer(5, this);
time.start();
}
public void actionPerformed(ActionEvent e) {
p.move();
repaint();
}
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2d = (Graphics2D) g;
g2d.drawImage(img, 0, 0, null);
g2d.drawImage(p.getImage(), p.getX(), p.getY(), null);
}
private class AL extends KeyAdapter {
public void keyReleased(KeyEvent e) {
p.keyReleased(e);
}
public void keyPressed(KeyEvent e) {
p.keyPressed(e);
}
}
}
The code for Dude:
package Ourgame;
import java.awt.Image;
import java.awt.event.KeyEvent;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
public class Dude {
int x, dx, y;
Image still;
public Dude() {
ImageIcon i = new ImageIcon("/Users/appleuser/Desktop/the man.bmp");
still = i.getImage();
x = 10;
y = 172;
}
public void move() {
x = x + dx;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
public Image getImage() {
return still;
}
public void keyPressed(KeyEvent e) {
int key = e.getKeyCode();
if(key == KeyEvent.VK_LEFT);
dx = -1;
if(key == KeyEvent.VK_RIGHT)
dx = 1;
}
public void keyReleased(KeyEvent e) {
int key = e.getKeyCode();
if(key == KeyEvent.VK_LEFT);
dx = 0;
if(key == KeyEvent.VK_RIGHT)
dx = 0;
}
}
The code for Frame:
package Ourgame;
import javax.swing.JFrame;
public class Frame {
public static void main(String[] args){
JFrame frame = new JFrame("2D game");
frame.add(new Board());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(1200, 365);
frame.setVisible(true);
}
}

You might just need to call JFrame.pack(). It's possible the layout manager hasn't set the bounds of your Board. Try:
frame.getContentPane().add(new Board());
frame.pack();
frame.setVisible(true);
If this doesn't work then I suggest you follow the other advice on here: use a Debugger and/or check your image paths. "/Users/appleuser/Desktop" is definitely not an image.

Try invoking your Swing code on the EDT:
package Ourgame;
import javax.swing.JFrame;
public class Frame
{
public static void main(String[] args)
{
SwingUtilities.invokeLater( new Runnable()
{
#Override
public void run()
{
JFrame frame = new JFrame("2D game");
frame.add(new Board());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(1200, 365);
frame.setVisible(true);
}
});
}
}