I'm trying to write a program that allows a user to move a shape with arrow keys and change its color with the enter key. I wasn't taught anything about GUIs or event-based programming, so this is my first experience with any of that. I think I understand the basics of it, but I'm having trouble just finishing the syntax to make everything run. The tutorials I find online use timers, which I'm not using. Here's my current code:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Lab15Panel extends JPanel
{
Color[] colors = new Color[]{Color.blue, Color.green, Color.red, Color.orange, Color.yellow};
int initialX = 90;
int initialY = 80;
public void paintComponent(Graphics g)
{
super.paintComponent(g);
g.setColor(colors[0]);
g.fillRect(initialX, initialY, 100, 100);
Lab15Key listen = new Lab15Key();
}
private class Lab15Key implements KeyListener
{
#Override
public void keyTyped(KeyEvent event)
{
if (event.getKeyChar() == KeyEvent.VK_LEFT)
{
initialX++;
}
}
#Override
public void keyReleased(KeyEvent event)
{}
#Override
public void keyPressed(KeyEvent event)
{}
}
}
I make my frame in a different class. Right now I'm unsure of two things:
1. How do I use addKeyListener with the filled shape? Is there a way to refer to the filled shape?
2. Is my idea of "moving" the shape correct? That is, creating variables outside of the methods for the position of the shape and then using my KeyEvents to change those numbers? Or will the shape not be moved in this case? (Note I've only written the code for the up key event.)
Any help you can give me would be appreciated. I'm definitely a Java novice, and I'm just trying to understand these basic concepts but the resources I have aren't helping.
You need to add your KeyListener to your panel to actually make it listen for key presses. This is known as registering the listener. I would put it in the constructor:
public Lab15Panel()
{
Lab15Key listen = new Lab15Key();
this.addKeyListener(listen);
}
Without this step, you are creating the listener, but it has nobody to tell when it hears something.
If you just want your panel to get repainted each time the key gets pressed, then you could do something like this in your KeyListener:
#Override
public void keyTyped(KeyEvent event)
{
if (event.getKeyChar() == KeyEvent.VK_LEFT)
{
initialX++;
}
Lab15Panel.this.repaint(); // Calls repaint on the instance of the enclosing class
}
There are a number of issues working against you...
You've not registered the KeyListener with the component, so it will never receive key events
You don't repaint the panel when you change the state of the rectangle, remember, Swing uses a passive painting algorithm, so it only paints the UI when it thinks it needs to. You need to give Swing a nudge by calling repaint
Your component isn't focusable, meaning that even if you did the other two things, you'd probably still not get it it work.
KeyListener is a pain, it will only be triggered of the component it is attached to IS focusable AND HAS focus, generally, you are better off use Key Bindings
See How to use key bindings for more details
Related
I was playing around in Java and trying to make an autoclicker just as a challenge for myself. I was making key bindings to turn it on and off when I discovered that I needed to turn off a while loop from a different class. Normally I would think this to be easy but I am using actions, so the action keeps playing until it is broken. I thought about it for a little bit and came to the conclusion that I needed to ask for a keybind within an action, but I have no idea how to do this. Here is my code right now if you want to help me make some improvements
package autoclicker;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Autoclicker {
JFrame frame;
JLabel label;
boolean endis;
Action enableAction;
public Autoclicker() {
frame = new JFrame("Autoclicker");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(420, 420);
frame.setLayout(null);
label = new JLabel();
label.setBackground(Color.red);
label.setBounds(100, 100, 100, 100);
label.setOpaque(true);
enableAction = new EnableAction();
label.getInputMap().put(KeyStroke.getKeyStroke("UP"), "enableAction");
label.getActionMap().put("enableAction", enableAction);
frame.add(label);
frame.setVisible(true);
}
public class EnableAction extends AbstractAction {
#Override
public void actionPerformed(ActionEvent e) {
endis = true;
try {
Robot robot = new Robot();
while(endis) {
robot.mousePress(InputEvent.BUTTON1_MASK);
robot.mouseRelease(InputEvent.BUTTON1_MASK);
}
} catch (AWTException e1) {
e1.printStackTrace();
}
}
}
}
Assuming you want to use your autoclicker on other programs besides the java application, this isn't an easy thing to do. Java Swing was only designed to get events (such as keyboard presses) from the window that's currently focused on.
However, according to MasterID on this stack overflow post, it is possible with this library: https://github.com/kwhat/jnativehook. I haven't used this library myself though.
I've made my own auto clicker a long time ago, and here's how I dealt with exiting the loop. Mouse Position is something that is easy to get in Java. MouseInfo.getPointerInfo().getLocation(); So, rather than breaking on a keypress (requiring JFrame focus in Swing), you can break on if the mouse has been moved. In your loop, if the mouse is ever not in the same position, that means it has been moved, so exit the loop.
Perhaps something like this:
public void mainLoop() {
// Sleep for an amount of time to get mouse into proper position
Thread.sleep(4000);
...
Point p = MouseInfo.getPointerInfo().getLocation();
int lastX = (int)p.getX();
int lastY = (int)p.getY();
while(!isMoved(lastX, lastY)) {
// Do Click or other Stuff...
}
}
/** Returns true if the last x and y position don't match the current mouse x and y position on the screen. False if same position. */
public boolean isMoved(int lastX, int lastY){
Point p = MouseInfo.getPointerInfo().getLocation();
return (int)p.getX() != lastX || (int)p.getY() != lastY;
}
This breaks out of the loop if the mouse is ever moved. And if you want to use Robot.mouseMove(), you could make a simple wrapper class for Robot to handle updating the last position for you.
I am a novice coder, have a tiny bit of experience with C++ about 10 years ago and now learning java (it's been about 4-5 months). I have a little collaborative project going, and I've got some things to figure out.
Here's the code:
import java.awt.event.*;
import java.awt.*;
import javax.swing.JFrame;
import java.util.Scanner;
import java.util.Random;
public class Game extends JFrame {
GamePanel panel;
int[][] grid;
int size;
//...and some other variables
public Game(String title) {
super(title);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
panel = new GamePanel(grid,size);
this.add(panel);
Button button = new Button("WHAT");
button.setBounds(-100, -100, 70, 70);
this.add(button);
button.addKeyListener(new KeyHandler());
}
class KeyHandler extends KeyAdapter {
public void keyPressed(KeyEvent e) {
int keycode = e.getKeyCode();
switch(keycode) {
//arrow keys input and stuff
}
if(checkForWin()) //checkForWin() returns a boolean value for win/loss
//won the game, thus end the thread here
if(checkForLoss()) // similar stuff as checkForLoss()
//lost the game, thus end the thread here
//...update the panel
panel.repaint();
}
}
public static void main(String [] args) {
Game me = new Game("GAME");
me.setVisible(true);
}
}
So that's pretty much how the whole game thing looks like.
And I have questions:
I am using a button and put it at a negative position to make it invisible and using it as a mean of KeyListener. Is there any other way to add a key listener? ex) to the panel or something?
I want to change it so that each "level" is a thread and make it like
public static void main(String [] args) {
int level = 1;
do {
GameThread gt = new GameThread("Game");
// run() will have the game constructor inside
gt.setLevel(level);
gt.start();
gt.join(); //wait until the game "level" is finished
if(won)
level++;
if(lost)
level = 1;
} while(!checkIfDonePlaying())
}
Somewhat like this. I'm having trouble making the thread continue to run until the game level is actually finished. How do I do that?
I want to add a JLabel to show the score on the frame. But when I do that, the score doesn't update when I repaint() it. How do I do that?
Thanks in advance!
A few things:
Yes, there is a way to add a KeyListener to the panel, and that's by using key bindings. For example:
javax.swing.InputMap im = panel.getInputMap(panel.WHEN_IN_FOCUSED_WINDOW);
javax.swing.ActionMap am = panel.getActionMap();
im.put(javax.swing.KeyStroke.getKeyStroke("pressed UP"), "up");
am.put("up", new javax.swing.AbstractAction() {
#Override
public void actionPerformed(ActionEvent ev) {
// handle up arrow key action here
}
});
Swing is an event-driven environment, so do-while loops should not be used. Instead, use a Swing timer that periodically checks if your level has been completed.
Since you're not doing any custom painting on your JLabel, you shouldn't be using repaint. Instead, use its setText method.
Here's a solution for your first issue:
panel.setFocusable(true);
panel.addKeyListener(this);
Then you should just be able to do the usual key listener methods. Be sure to implement KeyListener!
Solutions for your other issues on their way. (Actually take #TNT 's suggestion and use keybindings, I'm more comfortable with listeners but for games I usually use lwjgl or slick2d)
2.
I feel that running your programs levels may be a bit inefficient (that may just be me) I would suggest having one thread in a run method and have the following:
Public void reset(int level)
{
//reset all variables based on local variable level...
}
Call it like this:
Reset(++currentLevel)); //use ++ before currentLevel so it adds to it and then resets
And you could easily use switch cases to do some special stuff if you want
Switch(level){
case 1: //...
}
And so forth. (I'm typing on mobile sorry for weird caps)
I'm working on a school project that has two images...a good guy and a bad guy. I'm using a timer to send the bad guy towards the good guy and that is working find, but I'm supposed to use a KeyListener to move the good guy towards or away from the bad guy....and then eventually attack but that is for later.
I'm just trying to get my "good guy" to move on KeyListener and its not getting called. I have no idea why.
Here is my constructor which calls my EventLIstener in my main panel:
//monster 1 coordinates
int mon1x = 0;
int mon1y = 300;
KeyListenerAction myKeyActionListener = new KeyListenerAction();
public BlobFighterPanel()
{
addKeyListener(myKeyActionListener);
this.setPreferredSize(new Dimension(1300,600)); //set size of main panel
//add button
startButton.addActionListener(startListener);
add(startButton);
}
Then below I have my KeyListener, but its not getting called:
public class KeyListenerAction implements KeyListener {
public void keyPressed (KeyEvent event)
{
switch(event.getKeyCode())
{
case KeyEvent.VK_LEFT:
goodx -= 10;
break;
case KeyEvent.VK_RIGHT:
System.out.println("Right");
goodx += 10;
break;
}
repaint();
}
public void keyTyped(KeyEvent event){}
public void keyReleased(KeyEvent event){}
}
What am I doing wrong? Why is my KeyListener not being called?
KeyListener is fickle mistress. It what's all the attention all the time or it isn't going to talk to you. What does this mean? In order for a KeyListener to raise events, the component is registered to must HAVE focus AND be focusable...
This means that the moment that another component becomes focused (like a button), the KeyListener will no longer respond.
Instead, you should use the key binding API, which was designed to overcome this issue. See How to Use Key Bindings for more details
I wanted to move my image using keyboard arrow keys. when I pressed the arrow keys it moves accordingly to the direction. However, I need to click on the image before able to move it. May I know how to edit the code such that I do not need to click on the image before able to move it? I would also like to know how to make the image appear from the left once it reaches right and vice versa.
My codes are :
Collect.addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent ke)
{
if(ke.getKeyCode() == KeyEvent.VK_LEFT)
{
Collect.setLocation(Collect.getX()-8,Collect.getY());
repaint();
}
if(ke.getKeyCode() == KeyEvent.VK_RIGHT)
{
Collect.setLocation(Collect.getX()+8,Collect.getY());
repaint();
}
}
});
Collect.addMouseListener(new MouseAdapter()
{
public void mouseClicked(MouseEvent me)
{
if(me.getClickCount() == 1)
{
boolean dd = Collect.isOptimizedDrawingEnabled();
boolean ff = Collect.requestFocusInWindow();
repaint();
}
}
});
You have look at KeyBindings, otherwise you have to JComponent#setFocusable() that nest the Image, example for Moving Image
Collect.requestFocusInWindow();
requestFocusInWindow()..
Requests that this Component get the input focus, if this Component's top-level ancestor is already the focused Window.
Make sure to call that only after the main window is visible and has the focus.
KeyListeners only work when the component which has the listener has focus. You are giving focus to what appears to be Collect by clicking on it. Then the listener works. You can add the listener to other things or force focus to remain on something like the outer frame by using a focus listener to regain focus whenever it is lost.
I've written a small Swing program that draws a head and when a JCheckBox instance is selected/unselected by the user a hat is drawn or removed from on top of the head. I'm having some trouble taking the next step with this program -- I'd like to add a boolean field to the Head class that causes this component to listen to mouse events with a MouseListener. From there, I'd like to use two methods to set this field to true/false and render the remaining three methods lame ducks. Also, how would I change the paintComponent method so that if the boolean value is true the object is drawn with open eyes, and if it's false, the head is drawn with the eyes closed? Please provide any advice you have. Many thanks!
import javax.swing.*;
import java.awt.geom.*;
import java.awt.*;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
public class Head extends JPanel {
Rectangle2D.Double chapeau, chapeau2;
Ellipse2D.Double bouche, visage, oeil1, oeil2;
JCheckBox box;
public Head(){
this.setBackground(Color.WHITE);
visage = new Ellipse2D.Double (150,130,100,100);
bouche = new Ellipse2D.Double (170,180,60,27);
chapeau = new Rectangle2D.Double (170,80,60,40);
chapeau2 = new Rectangle2D.Double (125,120,150,10);
oeil1 = new Ellipse2D.Double (170,150,20,20);
oeil2 = new Ellipse2D.Double (210,150,20,20);
box = new JCheckBox("Hat");
this.add(box);
box.addItemListener(new ItemListener(){
public void itemStateChanged(ItemEvent ie){
repaint();
}
});
}
public void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.setStroke(new BasicStroke(3.0f));
g2.setPaint(Color.BLUE);
g2.draw(visage);
g2.draw(oeil1);
g2.draw(oeil2);
g2.draw(bouche);
if(box.isSelected()){
g2.draw(chapeau);
g2.draw(chapeau2);
}
}
public static void main(String[] args){
JFrame f = new JFrame("Face Display Window");
f.setSize(425,285);
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.setVisible(true);
f.add(new Head());
}
}
----------------------------------- Second Try
import javax.swing.*;
import java.awt.geom.*;
import java.awt.*;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
public class Head extends JPanel implements MouseListener {
Rectangle2D.Double chapeau, chapeau2;
Ellipse2D.Double bouche, visage, oeil1, oeil2, oeil3, oeil4;
JCheckBox box;
boolean isClosed = false;
public Head(){
this.setBackground(Color.WHITE);
visage = new Ellipse2D.Double (150,130,100,100);
bouche = new Ellipse2D.Double (170,180,60,27);
chapeau = new Rectangle2D.Double (170,80,60,40);
chapeau2 = new Rectangle2D.Double (125,120,150,10);
oeil1 = new Ellipse2D.Double (170,150,20,20);
oeil2 = new Ellipse2D.Double (210,150,20,20);
oeil3 = new Ellipse2D.Double (175,155,25,25);
oeil4 = new Ellipse2D.Double (215,155,25,25);
box = new JCheckBox("Hat");
this.addMouseListener(this);
this.add(box);
box.addItemListener(new ItemListener(){
public void itemStateChanged(ItemEvent ie){
repaint();
}
});
}
public void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.setStroke(new BasicStroke(3.0f));
g2.setPaint(Color.BLUE);
g2.draw(visage);
g2.draw(oeil1);
g2.draw(oeil2);
g2.draw(bouche);
if(box.isSelected()){
g2.draw(chapeau);
g2.draw(chapeau2);
if(isClosed) {
g2.draw(oeil3);
g2.draw(oeil4);
}
else {
g2.draw(oeil1);
g2.draw(oeil2);
}
}
}
#Override
public void mouseClicked(MouseEvent e) {
isClosed = !isClosed;
repaint();
}
#Override
public void mousePressed(MouseEvent e) {
}
#Override
public void mouseReleased(MouseEvent e) {
}
#Override
public void mouseEntered(MouseEvent e) {
}
#Override
public void mouseExited(MouseEvent e) {
}
public static void main(String[] args){
JFrame f = new JFrame("Face Display Window");
f.setSize(425,285);
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.setVisible(true);
f.add(new Head());
}
}
I'm intentionally being a little vague here because I'm not sure if this is homework or not since you already have a fair amount of code that does a lot of stuff that is very similar to what you want it to and modifying it shouldn't be very difficult. However, if you're actually stuck, please clarify and I'll add more details if required.
I'd like to add a boolean field to the Head class that causes this component to listen to mouse events with a MouseListener.
This isn't too hard, let's walk through it. It's trivial to add a boolean field to your Head class - you simply declare boolean isClosed = false; - indicating that you begin the execution with the field set to false which your code will later interpret as the instruction to draw eyes open.
Your core requirement is the MouseListener. If you haven't already, check out the Java Trail for events; it explains how to implement a simple MouseListener. At this point, note that MouseListener is an interface and thus, you'd necessarily need to provide an implementation for all it's methods, even if they're empty-bodied methods. You may want to check out the MouseAdapter abstract class. It provides empty implementations of all these methods (and more) so that you only need to override the ones you need - this makes your code cleaner since you don't have a bunch of empty methods just to satisfy the compiler. This would solve the problem I believe you're referring to when you say 'and render the remaining three methods lame ducks' Of course, since you're already extending JPanel, you can't extend MouseAdapter as well so this doesn't apply here. But this (with other Adapters) is a useful class to keep in mind for later.
From there, I'd like to use two methods to set this field to true/false
If I understand you correctly, what you want is to toggle the value of isClosed on mouse clicks. So right now, you have a MouseListener/ MouseAdapter that doesn't really do anything. What you need to do next is provide an implementation for, lets say, the MouseClicked() method where you toggle the value of your boolean field. This is really easy as well - you simply invert the current value using the ! (NOT) operator and assign it back the variable - isClosed = !isClosed;. You may wish to read up on operators in Java in more detail.
Also, how would I change the paintComponent method so that if the boolean value is true the object is drawn with open eyes, and if it's false, the head is drawn with the eyes closed?
One way of doing this is to create two more shapes for the two closed eyes, similar to the ones you have for open eyes. Once you've done that, it's a simple matter of deciding which ones to draw (i.e. the closed eyes or the open ones) on the basis of the value of isClosed. So you'd use an if clause to check the value of isClosed and draw the open eyes when it's false and the closed eyes when true. Note that since your value of isClosed is being modified in your click handler, you need to make sure that you call repaint() when you change the value otherwise Swing may not update the panel immediately to show the change so then you won't see anything happen.
To sum it up, one way to do what you want is to make the following modifications to Head:
public class Head
extends JPanel
implements MouseListener {
//...all your other declarations still go here
boolean isClosed = false;
//also declare new 'eyes' which are closed
public Head() {
//..all your existing code is still here
//add code to instantiate closed eyes
//need to register a new MouseListener
//since head itself is a MouseListener, we can pass this as the argument
this.addMouseListener(this);
}
//...all your existing code still goes here
public void paintComponent(Graphics g) {
//...all your existing code still goes here
//decide which eyes to draw depending on isClosed
if(isClosed) {
//draw closed eyes
}
else {
//draw open eyes
}
//draw everything else as before
}
//implementation for MouseListener
//don't forget the rest of the MouseListener events
//mousePressed, mouseReleased, mouseEntered, mouseExited
public void mouseClicked(MouseEvent e) {
//toggle the value of isClosed
isClosed = !isClosed;
//must repaint
repaint();
}