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How do I properly move drawn Polygon in Swing

I am currently working on a 2D game which will be a puzzle. I got everything set up, got all my pieces added to my board (called View) and they're all aligned properly.
My next step is to select a piece by MouseEvent#mousePressed to be able to move it with the arrow keys with KeyEvent#keyPressed. The issue I'm currently running into is that my pieces will repaint themself whenever I move or resize the window. If I click on one piece and want to move it, the other pieces move too (in a way, they should not since one step equals about 100 pixel).
If anyone could tell me where my issue is and give me some advice, I would appreciate it.
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Polygon;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Puzzle {
public static void main(String[] args) {
SwingUtilities.invokeLater(Puzzle::new);
}
public Puzzle() {
JFrame frame = new JFrame("Puzzle");
frame.setSize(400, 600);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
View view = new View();
view.createPieces();
frame.setContentPane(view);
view.setFocusable(true);
MouseAdapterMod listener = new MouseAdapterMod(view);
view.addMouseListener(listener);
view.addKeyListener(listener);
frame.setVisible(true);
}
}
class View extends JPanel {
final List<Piece> pieces = new ArrayList<>();
public View() {
}
void createPieces() {
Piece topLeft = new Piece(100, 100, 0, Color.YELLOW);
pieces.add(topLeft);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D gc = (Graphics2D) g;
for (Piece needle : pieces) {
needle.translate(needle.getLocation().x, needle.getLocation().y);
gc.setColor(needle.color);
gc.fill(needle);
gc.draw(needle);
}
}
}
class Piece extends Polygon {
int x;
int y;
final Color color;
Point location;
Piece(int x, int y, int type, Color color) {
this.x = x;
this.y = y;
this.color = color;
this.location = new Point(x, y);
int[] arrX = new int[] { 0, 100, 100, -100, -100, 0 };;
int[] arrY = new int[] { 0, 0, -100, -100, 100, 100 };
for (int drawIndex = 0; drawIndex < arrX.length; drawIndex++) {
addPoint(arrX[drawIndex], arrY[drawIndex]);
}
}
Point getLocation() {
return location;
}
void setLocation(Point location) {
this.location = location;
}
}
class MouseAdapterMod implements MouseListener, KeyListener {
final View view;
Polygon current;
public MouseAdapterMod(View view) {
this.view = view;
}
#Override
public void mousePressed(MouseEvent e) {
for (Piece piece : view.pieces) {
if (piece.contains(e.getX(), e.getY())) {
current = piece;
System.out.println(current);
}
}
}
#Override
public void keyPressed(KeyEvent e) {
switch (e.getKeyCode()) {
case KeyEvent.VK_UP:
current.translate(0, -100);
view.repaint();
break;
case KeyEvent.VK_DOWN:
current.translate(0, +100);
view.repaint();
break;
case KeyEvent.VK_LEFT:
current.translate(-100, 0);
view.repaint();
break;
case KeyEvent.VK_RIGHT:
current.translate(+100, 0);
view.repaint();
break;
}
}
#Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
#Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseClicked(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
}
(Sorry for the indent, stackoverflow is messing it up)
EDIT: But the problem is, eventually I want to move my pieces using Piece#setLocation to always keep track of their current x/y coordinates. I figured, I need to invoke Piece#getLocation in my painting to draw them based on the location but yet I do not know how. Using Piece#setLocation literally does nothing.

If you revert back to your Piece code from this question, you can move pieces by:
#Override
public void keyPressed(KeyEvent e) {
switch (e.getKeyCode()) {
case KeyEvent.VK_UP:
view.translatePiece(0, -100);
break;
case KeyEvent.VK_DOWN:
view.translatePiece(0, +100);
break;
case KeyEvent.VK_LEFT:
view.translatePiece(-100, 0);
break;
case KeyEvent.VK_RIGHT:
view.translatePiece(+100, 0);
break;
}
}
And adding to your view:
void translatePiece(int dx, int dy) {
if (current != null) {
current.x += dx;
current.y += dy;
repaint();
}
}
The if (current != null) { ... } test will prevent your application from crashing if you press an arrow key before clicking on a piece, which it currently does.

You could, instead of translating the Polygon, translate the location, and use it for painting:
In keyPressed, replace current.translate to translate the location instead of the whole Polygon (you could override Piece#translate to call current.getLocation().translate for example).
In View#paintComponent, replace:
needle.translate(needle.getLocation().x, needle.getLocation().y);
with
gc.translate(needle.getLocation().x, needle.getLocation().y);
and add
gc.translate(-needle.getLocation().x, -needle.getLocation().y);
at the end of your for-loop.
This will translate the whole Graphics2D to paint a polygon, and revert it after.

Learning KeyEvents

I am relatively new to java and was trying to learn how to make a program where there is this circle and I can move it around using the arrow keys. After shifting through a bunch of examples I was able to put something together. Although I am unsure how to create a KeyEvent. Any help with what I am missing would be awesome.
This is what I have so far.
import javax.swing.WindowConstants;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.Color;
import java.awt.event.KeyEvent;
#SuppressWarnings("serial")
public class Game extends JPanel
{
int x = 0;
int y = 0;
private void moveBallUP() {
x = x + 0;
y = y + 1;
}
private void moveBallDOWN() {
x = x + 0;
y = y - 1;
}
private void moveBallLEFT() {
x = x + 1;
y = y + 0;
}
private void moveBallRIGHT() {
x = x - 1;
y = y + 0;
}
#Override
public void paint(Graphics g)
{
super.paint(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g.setColor(Color.red);
g2d.fillOval(y, x, 50, 50);
}
public static void main(String[] args) throws InterruptedException
{
JFrame frame = new JFrame("Sample Frame");
Game game = new Game();
frame.add(game);
frame.setSize(300, 400);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
if (event.getKeyCode() == KeyEvent.VK_UP)
{
game.moveBallUP();
game.repaint();
Thread.sleep(10);
}
if (event.getKeyCode() == KeyEvent.VK_DOWN)
{
game.moveBallDOWN();
game.repaint();
Thread.sleep(10);
}
if (event.getKeyCode() == KeyEvent.VK_LEFT)
{
game.moveBallLEFT();
game.repaint();
Thread.sleep(10);
}
if (event.getKeyCode() == KeyEvent.VK_RIGHT)
{
game.moveBallRIGHT();
game.repaint();
Thread.sleep(10);
}
}
}

There are several steps to solving this: first, use a KeyListener. Add the following code to the Game class; this will represent which buttons are pressed:
private boolean upPressed=false;
private boolean downPressed=false;
private boolean leftPressed=false;
private boolean rightPressed=false;
Then, add this to the main method:
frame.addKeyListener(new KeyListener() {
#Override
public void keyReleased(KeyEvent event) {
switch (event.getKeyCode()) {
case KeyEvent.VK_UP:
game.upPressed=false;
break;
case KeyEvent.VK_DOWN:
game.downPressed=false;
break;
case KeyEvent.VK_LEFT:
game.leftPressed=false;
break;
case KeyEvent.VK_RIGHT:
game.rightPressed=false;
break;
}
}
#Override
public void keyTyped(KeyEvent event) {
}
#Override
public void keyPressed(KeyEvent event) {
switch (event.getKeyCode()) {
case KeyEvent.VK_UP:
game.upPressed=true;
break;
case KeyEvent.VK_DOWN:
game.downPressed=true;
break;
case KeyEvent.VK_LEFT:
game.leftPressed=true;
break;
case KeyEvent.VK_RIGHT:
game.rightPressed=true;
break;
}
}
});
Basically, you are setting the variables we created to true when the buttons are pressed down and false when they are released. Finally, add a Timer in the main method:
Timer timer = new Timer(10,(e)->{
if (game.upPressed)
{
game.moveBallUP();
game.repaint();
}
if (game.downPressed)
{
game.moveBallDOWN();
game.repaint();
}
if (game.leftPressed)
{
game.moveBallLEFT();
game.repaint();
}
if (game.rightPressed)
{
game.moveBallRIGHT();
game.repaint();
}
});
timer.start();
This will fire every 10 milliseconds and call your move methods if the buttons are pressed.
I have tested this and know that it works, however your move methods move the circle in the wrong directions. I assume you can fix that.
EDIT: The mistake is in this line:
g2d.fillOval(y, x, 50, 50);
Change it to:
g2d.fillOval(x,y , 50, 50);

Image is not moving in applet

I want to move an Image ( here is rectangle ) in applet, applet draws it, but I wonder why the image is not moving? there is no compile error!
here is my code:
package game;
import java.awt.*;
import javax.swing.*;
import java.applet.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
public class Gamer extends JApplet implements KeyListener
{
private int x=50,y=50;
#Override
public void init( )
{
addKeyListener(this);
}
#Override
public void keyPressed(KeyEvent e)
{
int keyCode = e.getKeyCode();
switch( keyCode )
{
case KeyEvent.VK_UP:
if( y>0 ) //when up key is pressed and the position of the player is not on the edge
{
y=y-19;
repaint();
}
break;
case KeyEvent.VK_DOWN:
if( y<171 ) //when down key is pressed and the position of the player is not on the edge
{
y=y+19;
repaint();
}
break;
case KeyEvent.VK_LEFT:
if( x>0 )
{
x=x-15;
repaint();
}
break;
case KeyEvent.VK_RIGHT:
if( x<285 )
{
x=x+15;
repaint();
}
break;
}
}
#Override
public void paint( Graphics g ) //will draw the background and the character
{
g.fillRect(x, y, 200, 200);
}
#Override
public void keyReleased(KeyEvent arg0)
{
// TODO Auto-generated method stub
}
#Override
public void keyTyped(KeyEvent arg0)
{
// TODO Auto-generated method stub
}
}
When I pressed my up/down/left/write arrow , the rectangle is not moving .
Please explain why ? T.I.A.

The problem is that your applet doesn't catch the KeyEvent, so your paint method does not get called.
In fact there is an issue when you want to add KeyListener to JApplet and it's not working.
Solution is to implement KeyEventDispatcher instead of KeyListener. Also I changed the size of your rectangle from 200 to 20 in order to be able to see the movements of the rectangle better:
package game;
import java.awt.Graphics;
import java.awt.KeyEventDispatcher;
import java.awt.KeyboardFocusManager;
import java.awt.event.KeyEvent;
import javax.swing.JApplet;
public class Gamer extends JApplet implements KeyEventDispatcher {
private int x = 50, y = 50;
#Override
public void init() {
KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(this);
}
#Override
public void paint(Graphics g) // will draw the background and the character
{
super.paint(g); // <- added to your code to clear the background
// before re-painting the new square
g.fillRect(x, y, 20, 20);
}
#Override
public boolean dispatchKeyEvent(KeyEvent e) {
int keyCode = e.getKeyCode();
switch( keyCode )
{
case KeyEvent.VK_UP:
if( y>0 ) //when up key is pressed and the position of the player is not on the edge
{
y=y-19;
repaint();
}
break;
case KeyEvent.VK_DOWN:
if( y<171 ) //when down key is pressed and the position of the player is not on the edge
{
y=y+19;
repaint();
}
break;
case KeyEvent.VK_LEFT:
if( x>0 )
{
x=x-15;
repaint();
}
break;
case KeyEvent.VK_RIGHT:
if( x<285 )
{
x=x+15;
repaint();
}
break;
}
return false;
}
}
Hope this would be helpful.

Snake Game. Handle keyPressed method

I got the snake running down, now I try to get the keypressed() method to work. I don't think it's listening from the keyboard. My idea is for example if the the down key is pressed, the variable direction is set to 1 and the switch case statement would handle that. I doubt that the direction variable was't read by the switch case.
My main class:
package com.bin.snake;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
#SuppressWarnings("serial")
public class Game extends JPanel{
boolean playingSnake = true;
Snake snake = new Snake();
public Game() {
addKeyListener(new KeyListener() {
#Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
#Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
#Override
public void keyPressed(KeyEvent e) {
snake.keyPressed(e);
}
});
setFocusable(true);
}
public void paint(Graphics g) {// inherit paint method of JPanel class with
// parameter g type Graphics
// parameter g is the object to paint things
super.paint(g); // erase latest image
Graphics2D g2d = (Graphics2D) g; // casting g to Graphics2D type
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);// rendering
// image
snake.paint(g2d);
}
public static void main(String[] args) {
JFrame frame = new JFrame("Snake!");
frame.setVisible(true);
frame.setSize(800, 600);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Game game = new Game();
frame.add(game);
while (true) {
game.updateGame();
game.repaint();
try {
Thread.sleep(10);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
public void updateGame() {
snake.moveSnake();
}
}
My Snake Class:
package com.bin.snake;
import java.awt.Graphics2D;
import java.awt.event.KeyEvent;
public class Snake {
private Game game;
int iSnakeLength = 10;
int direction = 1;
final int SIDE = 13;
int[] snakeY = new int[2000];
int[] snakeX = new int[2000];
int xs = 0;
int ys = 0;
public void moveSnake() {
switch (direction) {
case 0:// up
snakeY[0] -=1.5;
break;
case 1:// down
snakeY[0] += 1.5;
break;
case 2:// right
snakeX[0] += 1.5;
break;
case 3:// left
snakeX[0] -=1.5;
break;
}
for (int i = iSnakeLength; i > 0; i--) {
snakeX[i] = snakeX[i - 1];
snakeY[i] = snakeY[i - 1];
}
}
public void paint(Graphics2D g) {
g.fillRect(snakeX[0], snakeY[0], SIDE, SIDE);
for (int i = 0; i < iSnakeLength; i++) {
g.fillRect(snakeX[i + 1], snakeY[i + 1], SIDE, SIDE);
}
}
public void keyPressed(KeyEvent e){
if(e.getKeyCode() == KeyEvent.VK_DOWN){
direction = 1;
}
if(e.getKeyCode() == KeyEvent.VK_UP){
direction = 0;
}
if(e.getKeyCode() == KeyEvent.VK_LEFT){
direction = 3;
}
if(e.getKeyCode() == KeyEvent.VK_RIGHT){
direction = 2;
}
}
}

I don't think it's listening from the keyboard. My idea
KeyEvents are only dispatched to the component with focus. A JPanel is not focusable by default.
To make a panel focusable you use:
panel.setFocusable( true );
Other comments:
Custom painting is done by overriding the paintComponent(...) method, not the paint() method. Read the Swing tutorial on Custom Painting for more information and examples.
You should NOT be using a KeyListener. Swing was designed to be used with Key Bindings. Read the Swing tutorial on How to Use Key Bindings. You can also check out Motion Using the Keyboard which contains working examples of moving a component using Key Bindings.
For animation you should be using a Swing Timer to schedule the animation. Check the table of contents from the tutorial links I have already provided. There is a section on How to Use Swing Timers.

My picture is moving too slowly

I am currently making a kind of adventure 2D game project for university.
I have drawn an array of pictures(walls,floor etc) and then the movable hero figure. The problem: without the array the figure is moving fine but with the array the movement starts to lag hard. Is it my Pc? or is my drawing method too "heavy"? Please take a look:
import java.awt.Graphics;
import java.awt.Rectangle;
public class World {
public static int WorldW = 16 , WorldH = 16;
public SpielElement[][] element = new SpielElement[WorldW][WorldH];
public int[][] level0 ={{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,4,0,0,0,0,0,0,0,0},
{0,0,0,1,1,1,1,1,1,1,1,6,0,0,0,0},
{0,0,0,1,1,1,5,1,1,1,1,1,0,0,0,0},
{0,0,0,1,1,6,1,1,2,1,5,1,0,0,0,0},
{0,0,0,1,1,1,1,5,1,1,1,1,0,0,0,0},
{0,0,0,1,1,1,0,0,0,1,1,1,0,0,0,0},
{0,0,0,0,0,1,1,3,1,1,0,0,0,0,0,0},
{0,0,0,0,0,1,1,1,1,1,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}};
public int[][] level1 ={{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
{0,0,0,1,0,0,0,0,1,1,1,1,2,0,1,0},
{0,4,0,1,0,0,5,1,1,1,1,1,1,0,1,0},
{0,1,0,1,0,0,0,0,0,0,1,0,0,0,1,0},
{0,1,1,1,1,1,1,1,0,0,1,1,1,1,1,0},
{0,1,0,0,0,0,0,0,0,0,1,0,0,1,0,0},
{0,1,1,1,0,0,1,1,1,1,1,0,0,1,0,0},
{0,0,0,1,0,0,1,0,0,0,0,0,0,0,0,0},
{0,1,0,1,1,1,1,1,1,1,1,1,0,0,3,0},
{0,1,0,1,0,0,0,0,0,1,0,1,0,0,1,0},
{0,1,0,1,1,1,1,0,0,1,0,1,0,0,1,0},
{0,1,0,1,0,0,1,0,0,1,0,1,1,1,1,0},
{0,1,0,0,0,0,1,0,0,1,0,0,1,0,0,0},
{0,1,1,1,1,6,1,1,0,1,0,0,1,0,0,0},
{0,0,0,0,0,0,0,0,0,1,0,0,1,1,1,0},
{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}};
public World(){
create();
}
public void create(){
for(int x = 0; x<WorldW; x++){
for(int y = 0; y<WorldH; y++){
element[x][y] = new SpielElement(x,y,level0[y][x]);
}
}
}
public void generate(Graphics g){
for(int x = 0; x<WorldW; x++){
for(int y = 0; y<WorldH; y++){
element[x][y].zeichne(g);
}
}
}
}
Well the int array is to define which kind of picture I need to draw and
i intend to first create all the Panels (SpielElement) and then draw them
Here is how i Draw them:
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.*;
public class SpielElement extends JPanel{
int posX,posY,type ;
BufferedImage wand, boden, tuer, schluessel;
public SpielElement(int x, int y,int z){
this.posX = x*40;
this.posY = y*40;
this.type = z;
try {
wand = ImageIO.read(SpielElement.class.getResource("/img/wand.png"));
boden = ImageIO.read(SpielElement.class.getResource("/img/boden.png"));
tuer = ImageIO.read(SpielElement.class.getResource("/img/tuer.png"));
schluessel = ImageIO.read(SpielElement.class.getResource("/img/schluessel.png"));
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public void zeichne(Graphics g){
switch(type){
case 0: g.drawImage(wand,posX,posY,boden.getWidth(),wand.getHeight(),null);
break;
case 1:g.drawImage(boden,posX,posY,boden.getWidth(),boden.getHeight(),null);
break;
case 2: g.drawImage(schluessel,posX,posY,schluessel.getWidth(),schluessel.getHeight(),null);
break;
case 3: g.drawImage(tuer,posX,posY,tuer.getWidth(),tuer.getHeight(),null);
break;
case 4: g.drawImage(boden,posX,posY,boden.getWidth(),boden.getHeight(),null);
break;
case 5:g.drawImage(boden,posX,posY,boden.getWidth(),boden.getHeight(),null);
break;
case 6: g.drawImage(boden,posX,posY,boden.getWidth(),boden.getHeight(),null);
break;
}
}
}
I hope u get what I am thinking by reading the code and hopefully see what is wrong. There are no Syntax errors whatsoever but its so damn slow. In the end added all of this onto a JPanel Board which is added on a JFrame
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
public class Board extends JPanel implements KeyListener{
private final int BREITE = 700;
private final int HOEHE = 700;
Hunter Held ;
World Welt;
public Board(){
super();
Held = new Hunter(200,200);
Welt = new World();
this.setBackground(Color.BLACK);
}
public void paint(Graphics g){
super.paint(g);
Welt.generate(g);
Held.draw(g);
}
#Override
public void keyPressed(KeyEvent e) {
// TODO Auto-generated method stub
if (e.getKeyCode() == KeyEvent.VK_LEFT)
Held.posX = Held.posX - 10;
if (e.getKeyCode() == KeyEvent.VK_RIGHT)
Held.posX = Held.posX + 10;
if (e.getKeyCode() == KeyEvent.VK_UP)
Held.posY = Held.posY - 10;
if (e.getKeyCode() == KeyEvent.VK_DOWN)
Held.posY = Held.posY + 10;
this.repaint();
}
#Override
public void keyReleased(KeyEvent arg0) {
// TODO Auto-generated method stub
}
#Override
public void keyTyped(KeyEvent arg0) {
// TODO Auto-generated method stub
}
}
the Hero(Held) is drawn the exact way like the other images with its Coordinates beeing altered everytime i press keys and thus repainted.
I will refrain from further code dumping at this point. This is how it looks like in the end:
http://puush.me/account?pool=1468274
(Sorry no reputation yet)
The figure on Scrren moves on KeyInput but with lags...
This is my first question and i hope it is detailed enough.
Sry in advance if my problem is stupid only started 2 weeks ago with programming in general.
Constructive critizism is adviced. sry for code Dumping...

Until I saw you mentioned JPanel and JFrame, I thought it was an Android related question...
Anyway maybe you should draw them in a new thread, on an invisible canvas/image/cache, whatever... then bring it to front and draw another frame in background.
Sorry, I don't know how to do it with Swing, but I think that's how all animation frameworks work. In Android people do all these dirty work in background thread...