Develop Reference

Calling the methods in a class in Java

I have a very basic question: my MainDriver class wishes to run the Line class when a button Line is pressed; however, I know we cannot run a whole class, so if there's another way to implement this, please let me know.
The following is the MainDriver class; I've highlighted the relevant bit in astericks.
package javafx.scene;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
//import java.awt.*;
class MainDriver extends JFrame implements ActionListener {
/**
*
*/
private static final long serialVersionUID = 1L;
// create a frame
static JFrame frame;
// main function
public static void main(String args[])
{
// create a frame
frame = new JFrame("DrawShapes");
try {
// set look and feel
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
}
catch (Exception e) {
System.err.println(e.getMessage());
}
// create a object of class
Line line = new Line();
// create number buttons and some operators
JButton b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bs, bd, bm, be, beq;
// create number buttons
b0 = new JButton("line");
b1 = new JButton("circle");
b2 = new JButton("triangle");
b3 = new JButton("rectangle");
b4 = new JButton("quadrilateral");
b5 = new JButton("move");
b6 = new JButton("copy");
b7 = new JButton("delete");
b8 = new JButton("random");
b9 = new JButton("import");
ba = new JButton("export");
bs = new JButton("");
bd = new JButton("/");
bm = new JButton("*");
beq = new JButton("C");
// create . button
be = new JButton(".");
// create a panel
JPanel p = new JPanel();
// add action listeners
b0.addActionListener(line);
//add more later
// add elements to panel
p.add(b0);
p.add(ba);
p.add(b1);
p.add(b2);
p.add(b3);
p.add(bs);
p.add(b4);
p.add(b5);
p.add(b6);
p.add(bm);
p.add(b7);
p.add(b8);
p.add(b9);
p.add(bd);
p.add(be);
p.add(b0);
p.add(beq);
// set Background of panel
p.setBackground(Color.blue);
// add panel to frame
frame.add(p);
frame.setSize(450, 400);
}
public void actionPerformed(ActionEvent e)
{
String s = e.getActionCommand();
*************************
if (s.equals("line")) {
//Im not sure how to implement the object here
}
***************************
}
}
And here's the Line class
package javafx.scene;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
#SuppressWarnings("serial")
public class Line extends JPanel implements MouseListener,ActionListener{
private int x,y,x2,y2,a=1;
public Line(){
super();
addMouseListener(this);
}
public void paint(Graphics g){
int w = x2 - x ;
int h = y2 - y ;
int dx1 = 0, dy1 = 0, dx2 = 0, dy2 = 0 ;
if (w<0) dx1 = -1 ; else if (w>0) dx1 = 1 ;
if (h<0) dy1 = -1 ; else if (h>0) dy1 = 1 ;
if (w<0) dx2 = -1 ; else if (w>0) dx2 = 1 ;
int longest = Math.abs(w) ;
int shortest = Math.abs(h) ;
if (!(longest>shortest)) {
longest = Math.abs(h) ;
shortest = Math.abs(w) ;
if (h<0) dy2 = -1 ; else if (h>0) dy2 = 1 ;
dx2 = 0 ;
}
int numerator = longest >> 1 ;
for (int i=0;i<=longest;i++) {
g.fillRect(x,y,1,1);
numerator += shortest ;
if (!(numerator<longest)) {
numerator -= longest ;
x += dx1 ;
y += dy1 ;
} else {
x += dx2 ;
y += dy2 ;
}
}
}
public void mouseClicked(MouseEvent mouse) {
if (a == 1) {
a = 0;
x = x2 = mouse.getX();
y = y2 = mouse.getY();
} else {
a = 1;
x = x2;
y = y2;
x2 = mouse.getX();
y2 = mouse.getY();
repaint();
}
}
public void mouseEntered(MouseEvent mouse){ }
public void mouseExited(MouseEvent mouse){ }
public void mousePressed(MouseEvent mouse){ }
public void mouseReleased(MouseEvent mouse){ }
#Override
public void actionPerformed(ActionEvent arg0) {
// TODO Auto-generated method stub
}
}

Here is an example on how to go about it:
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.SwingUtilities;
public class Main {
private static void drawPoint(final Graphics g, final Point p) {
g.drawLine(p.x - 10, p.y, p.x + 10, p.y);
g.drawLine(p.x, p.y - 10, p.x, p.y + 10);
}
private static void drawLine(final Graphics g, final Point p1, final Point p2) {
g.drawLine(p1.x, p1.y, p2.x, p2.y);
}
public static interface ShapeByPoints {
int getPointCount();
void draw(final Graphics g, final Point... points);
}
public static class DrawPanel extends JPanel {
private final ArrayList<Point> points;
private ShapeByPoints s;
public DrawPanel() {
points = new ArrayList<>();
s = null;
}
public void setShape(final ShapeByPoints s) {
this.s = s;
points.clear();
repaint();
}
public void modifyLastPoint(final Point p) {
points.get(points.size() - 1).setLocation(p);
repaint();
}
public void addPoint(final Point p) {
if (s != null && points.size() == s.getPointCount())
points.clear();
points.add(p);
repaint();
}
#Override
protected void paintComponent(final Graphics g) {
super.paintComponent(g);
((Graphics2D) g).setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
if (s != null && s.getPointCount() == points.size())
s.draw(g, points.toArray(new Point[s.getPointCount()]));
else {
points.forEach(p -> drawPoint(g, p));
for (int i = 1; i < points.size(); ++i)
drawLine(g, points.get(i - 1), points.get(i));
}
}
}
public static class EllipseByPoints implements ShapeByPoints {
#Override
public int getPointCount() {
return 2;
}
#Override
public void draw(final Graphics g, final Point... points) {
g.drawOval(Math.min(points[0].x, points[1].x), Math.min(points[0].y, points[1].y), Math.abs(points[1].x - points[0].x), Math.abs(points[1].y - points[0].y));
}
}
public static class PolygonByPoints implements ShapeByPoints {
private final int points;
public PolygonByPoints(final int points) {
this.points = points;
}
#Override
public int getPointCount() {
return points;
}
#Override
public void draw(final Graphics g, final Point... points) {
for (int i = 1; i < this.points; ++i)
drawLine(g, points[i - 1], points[i]);
drawLine(g, points[this.points - 1], points[0]);
}
}
public static class LineByPoints extends PolygonByPoints {
public LineByPoints() {
super(2);
}
}
public static class RectangleByPoints implements ShapeByPoints {
#Override
public int getPointCount() {
return 2;
}
#Override
public void draw(final Graphics g, final Point... points) {
g.drawRect(Math.min(points[0].x, points[1].x), Math.min(points[0].y, points[1].y), Math.abs(points[1].x - points[0].x), Math.abs(points[1].y - points[0].y));
}
}
private static JRadioButton createButton(final String buttonText, final ButtonGroup bg, final DrawPanel dp, final ShapeByPoints s) {
final JRadioButton btn = new JRadioButton(buttonText);
btn.addActionListener(e -> dp.setShape(s));
bg.add(btn);
return btn;
}
public static void main(final String[] args) {
SwingUtilities.invokeLater(() -> {
final DrawPanel dp = new DrawPanel();
final MouseAdapter ma = new MouseAdapter() {
#Override
public void mousePressed(final MouseEvent mevt) {
dp.addPoint(mevt.getPoint());
}
#Override
public void mouseDragged(final MouseEvent mevt) {
dp.modifyLastPoint(mevt.getPoint());
}
#Override
public void mouseReleased(final MouseEvent mevt) {
dp.modifyLastPoint(mevt.getPoint());
}
};
dp.setPreferredSize(new Dimension(500, 350));
dp.addMouseListener(ma);
dp.addMouseMotionListener(ma);
final ButtonGroup bg = new ButtonGroup();
final JPanel buttons = new JPanel();
buttons.add(createButton("Line", bg, dp, new LineByPoints()));
buttons.add(createButton("Ellipse", bg, dp, new EllipseByPoints()));
buttons.add(createButton("Rectangle", bg, dp, new RectangleByPoints()));
buttons.add(createButton("Triangle", bg, dp, new PolygonByPoints(3)));
buttons.add(createButton("Pentagon", bg, dp, new PolygonByPoints(5)));
//... keep creating buttons here ...
final JPanel contents = new JPanel(new BorderLayout());
contents.add(dp, BorderLayout.CENTER);
contents.add(buttons, BorderLayout.PAGE_START);
final JFrame frame = new JFrame("Clicking shapes.");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(contents);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
});
}
}
Notes:
Don't use paint unless there is good reason, which usually isn't. In most cases you want to draw the panel, in which case paintComponent should be enough.
Dont' forget to firstly call super.paintComponent inside paintComponent override. This should be the first call, because it will clear the panel for you from previous drawings.
Decide if you want to add JComponents which will draw the shapes, or draw the shapes yourself in a sub-classed panel. In this case, it seems like you are trying both (because Line extends JPanel and you also override paint). In my opinion, in this case, using an abstraction of a shape to be drawn between some points will do the job. That's why I created ShapeByPoints interface.
Swing is not thread safe, which means there can be conditions between competing accesses of the same variable. To avoid such scenarios, you can run every Swing related operation at the Event Dispatch Thread (or EDT for short). To explicitly make a call in the EDT, invoke a method like SwingUtilities.invokeLater, SwingUtilities.invokeAndWait, EventQueue.invokeLater and so on... There is enough material on the Internet about this topic. For example here.
Basically everything is redesigned from scratch in my approach (ie I did not modify your example code, because I guessed it would take a little bit more time, but that's just a guess).
I just created the ShapeByPoints interface which specifies how a shape is supposedly drawn (ie number of points it needs, and a draw method to do the drawing).
Then I created a DrawPanel extends JPanel which contains the state of each operation. For example if the user selects a pentagon to be drawn, he needs 5 points, but what happens when he/she has clicked only twice?... The DrawPanel is responsible for such scenarios and also for drawing the given shape when all the points are completed/clicked.
I added an instance of a DrawPanel in the frame, a MouseAdapter for user interaction and a couple of buttons to demonstrate this logic.
All you need to do now, is to implement ShapeByPoints as you like and supply an instance of it to the DrawPanel depending of the button pressed. I already did some examples on how to do it in the code (like an EllipseByPoints, LineByPoints, RectangleByPoints and PolygonByPoints).
Finally, as a bonus, I added the ability to drag the clicked points (ie not only click them, but click-and-drag them).
Hope it helps.

How to add Panel on mouse location?

I want to add a Panel (which is on other panel) on mouse position. When I add now, panel's location is next to previous panel.
jPanel1.setLayout(new FlowLayout());
JPanel newPanel = new JPanel();
newPanel.setBackground(Color.red);
jPanel1.add(newPanel);
newPanel.setLocation(300,300);
jPanel1.revalidate();
jPanel1.repaint();
Point point = newPanel.getLocation();
int x = point.x;
int y = point.y;
newPanel.setLocation(x+5,y+5);

If you need to place a Swing component in a random position, then you will need a layout manager that would allow this, and FlowLayout, along with most standard managers, won't. The most common one to use is the simplest -- a null layout, e.g., someJPanel.setLayout(null); -- that is complete absence of a layout manager, but this comes with its own host of troubles, and so I try to avoid use of these as much as possible.
If your goal however is to move a red square, then best to keep things as simple as possible, and instead of creating and moving a JPanel, create and move something much lighter in weight, a Rectangle.
e.g.,
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.*;
public class MovingRect extends JPanel {
private static final long serialVersionUID = 1L;
private static final Color RECT_COLOR = Color.RED;
private static final int RECT_W = 300;
private Rectangle rect = new Rectangle(0, 0, RECT_W, RECT_W);
public MovingRect() {
setPreferredSize(new Dimension(800, 650));
MyMouse myMouse = new MyMouse();
addMouseListener(myMouse);
addMouseMotionListener(myMouse);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(RECT_COLOR);
((Graphics2D) g).fill(rect);
}
private class MyMouse extends MouseAdapter {
private Point p0;
private Point pRect;
#Override
public void mousePressed(MouseEvent e) {
if (e.getButton() != MouseEvent.BUTTON1) {
return;
}
if (rect.contains(e.getPoint())) {
p0 = e.getPoint();
pRect = rect.getLocation();
}
}
#Override
public void mouseDragged(MouseEvent e) {
if (p0 != null) {
drag(e);
}
}
#Override
public void mouseReleased(MouseEvent e) {
if (p0 != null) {
drag(e);
p0 = null;
}
}
private void drag(MouseEvent e) {
// use simple geometry to move the rectangle
Point p1 = e.getPoint();
int x = p1.x - p0.x + pRect.x;
int y = p1.y - p0.y + pRect.y;
rect = new Rectangle(x, y, RECT_W, RECT_W);
repaint();
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> createAndShowGui());
}
private static void createAndShowGui() {
MovingRect mainPanel = new MovingRect();
JFrame frame = new JFrame("Moving Rectangle");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
Code explanation
The rectangle to draw, initially placed at 0, 0:
private Rectangle rect = new Rectangle(0, 0, RECT_W, RECT_W);
In the constructor, set the drawing JPanel's preferred size, and create our mouse listener (actually a MouseAdapter) that will move the rectangle, and add the MouseAdapter as a MouseListener and MouseMotionListener to our drawing (main) JPanel:
public MovingRect() {
setPreferredSize(new Dimension(800, 650));
MyMouse myMouse = new MyMouse();
addMouseListener(myMouse);
addMouseMotionListener(myMouse);
}
Draw the rectangle within this JPanel's paintComponent method after doing clean-up painting by calling the super's method:
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(RECT_COLOR);
((Graphics2D) g).fill(rect);
}
The mouse adapater that does the moving. It uses simple geometry of vector addition to calculate where to move
private class MyMouse extends MouseAdapter {
private Point p0;
private Point pRect;
#Override
public void mousePressed(MouseEvent e) {
if (e.getButton() != MouseEvent.BUTTON1) {
// if not button 1, then get out of here
return;
}
if (rect.contains(e.getPoint())) {
// get the first point of the mouse press and the rectangle's first position
p0 = e.getPoint();
pRect = rect.getLocation();
}
}
#Override
public void mouseDragged(MouseEvent e) {
if (p0 != null) {
drag(e);
}
}
#Override
public void mouseReleased(MouseEvent e) {
if (p0 != null) {
drag(e);
p0 = null; // set the first pressed point to null -- stop the listener
}
}
private void drag(MouseEvent e) {
// use simple geometry to move the rectangle
Point p1 = e.getPoint();
int x = p1.x - p0.x + pRect.x;
int y = p1.y - p0.y + pRect.y;
// create a new Rectangle with the position calculated above
rect = new Rectangle(x, y, RECT_W, RECT_W);
// ask Java to repaint the main JPanel
repaint();
}
}

Creating animated text that loops on itself

I'm trying to make a news ticker type thing where a string is entered and inside of a JPanel the text is looped.
I know it moves currently at about 90 pixels a second and that there is about 16 pixels per char in this font. So what I am asking is how I can use this information to make it so that after a timer runs for a certain time, a new animated text is spawned, and how after the 1st animated text leaves the screen completely, how to delete it from the memory.
This is what I got so far, the code is borrowed heavily from here : Java Animate JLabel, So also if you see any unneeded code in there, let me know.
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.util.EnumMap;
import javax.swing.*;
#SuppressWarnings("serial")
public class AnimateExample extends JPanel {
private static final int TIMER_DELAY = 20;
private static final String KEY_DOWN = "key down";
public static final int TRANSLATE_SCALE =2;
private static final Font BG_STRING_FONT = new Font(Font.SANS_SERIF,
Font.BOLD, 32);
private EnumMap<Direction, Boolean> dirMap =
new EnumMap<AnimateExample.Direction, Boolean>(Direction.class);
private BufferedImage image = null;
private int posX = 100;
private int posY = 50;
Timer t;
public AnimateExample() {
for (Direction dir : Direction.values()) {
dirMap.put(dir, Boolean.TRUE);
}
t = new Timer(TIMER_DELAY, new TimerListener());
t.start();
ActionMap actionMap = getActionMap();
for (final Direction dir : Direction.values()) {
actionMap.put(dir.Left + KEY_DOWN, new AbstractAction() {
#Override
public void actionPerformed(ActionEvent arg0) {
dirMap.put(dir, true);
}
});
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g.setFont(BG_STRING_FONT);
g.setColor(Color.LIGHT_GRAY);
g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
String s = "Hi, I'm trying to make a news ticker type thing where a string is entered and inside of a JPanel the text is looped.I know it moves currently at about 90 pixels a second and that there is about 16 pixels per char in this font. So what I am asking is how I can use this information to make it so that after a timer runs for a certain time, a new animated text is spawned, and how after the 1st animated text leaves the screen completely, how to delete it from the memory.";
g.drawString(s, posX, posY);
}
private class TimerListener implements ActionListener {
public void actionPerformed(java.awt.event.ActionEvent e) {
for (Direction dir : Direction.values()) {
if (dirMap.get(dir)) {
posX += dir.getX() * TRANSLATE_SCALE;
posY += dir.getY() * TRANSLATE_SCALE;
}
}
repaint();
if(posX<-500)
{
t.stop();
}
};
}
enum Direction {
Left( KeyEvent.VK_LEFT, -1, 0);
private int keyCode;
private int x;
private int y;
private Direction(int keyCode, int x, int y) {
this.keyCode = keyCode;
this.x = x;
this.y = y;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
}
private static void createAndShowGui() {
AnimateExample mainPanel = new AnimateExample();
JFrame frame = new JFrame("Animate Example");
frame.setUndecorated(true);
frame.setSize(1600, 900);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(null);
frame.add(mainPanel);
mainPanel.setBounds(new Rectangle(1600,400));
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
EDIT:
I was also thinking that perhaps resetting the X position after a certain amount of time or distance, but the problem with that would be that it would require that the area would be blank for one screen length. If you have a work around for that, it would also be great.

You could check out the Marquee Panel. It uses a different approach than most scrollers. You add actual components to the panel and the components scroll.
This allows you to scroll text or images. You can use labels with HTML so you can have colored text etc. The message will continue to scroll until you manually stop the scrolling.
Currently there is no automatic mechanism for replacing a scrolling message. Although you could easily create a List or Queue of messages. Then when a message has finished scrolling completely you just remove the current message and add a new one.
Following is the section code from the MarqueePanel class you would need to change:
public void actionPerformed(ActionEvent ae)
{
scrollOffset = scrollOffset + scrollAmount;
int width = super.getPreferredSize().width;
if (scrollOffset > width)
{
scrollOffset = isWrap() ? wrapOffset + scrollAmount : - getSize().width;
// add code here to swap component from the List or Queue
}
repaint();
}
Of course you would also need to add a method to the class to add a component to the List or Queue.

Don't worry about the character width, as different fonts can produce variable character widths. Instead use FontMetrics to measure the String width and determine it the xPos <= -stringWidth, this is when the text would be fully off the left hand side of the screen.
You could use a Queue of some kind to manage text, popping of the next one as you need it. This example simply pops the last message onto the end of the queue, so it will keep repeating
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.LinkedList;
import java.util.Queue;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
Queue<String> queue = new LinkedList<>();
queue.add("I have something to say, it's better to burn out then fade away");
queue.add("Banana peels");
queue.add("Don't worry if plan A fails, there are 25 more letters in the alphabet");
queue.add("When the past comes knocking, don't answer. It has nothing new to tell you");
queue.add("I know the voices in my head aren't real..... but sometimes their ideas are just absolutely awesome!");
TickerTapPane pane = new TickerTapPane();
pane.setMessages(queue);
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(pane);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TickerTapPane extends JPanel {
private Queue<String> queue;
private String message;
private int xPos;
public TickerTapPane() {
Timer timer = new Timer(40, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (message == null) {
message = queue.remove();
xPos = getWidth();
}
xPos -= 4;
FontMetrics fm = getFontMetrics(getFont());
int stringWidth = fm.stringWidth(message);
if (xPos <= -stringWidth) {
queue.add(message);
xPos = getWidth();
message = queue.remove();
}
repaint();
}
});
timer.start();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (message != null) {
Graphics2D g2d = (Graphics2D) g.create();
FontMetrics fm = g2d.getFontMetrics();
int yPos = ((getHeight() - fm.getHeight()) / 2) + fm.getAscent();
g2d.drawString(message, xPos, yPos);
g2d.dispose();
}
}
protected void setMessages(Queue<String> queue) {
this.queue = queue;
}
}
}

Moving objects and timers

I have a screen with say 500 width and 400 height, and I have a vector with a bunch of shapes. let say the vector has 2 different shapes for example. I want the object to randomly pop up from the bottom of the screen reach a certain ascent and then fall back down (similar to game fruit ninja, where the fruits are my shapes).
In my main (view) I have a vector of shapes of which i instantiate the timers, add to array and place them in the buttom of the screen using the translate function. My timer takes in an action listener which basically changes the translate of the shape to move up till ascent and then down, but my problem is that all the shapes start at the same time regardless.
Something like this:
Shape f = new Shape(new Area(new Ellipse2D.Double(0, 50, 50, 50)));
f.translate(0, 400);
f.timer = new Timer( 10 , taskPerformer);
f.timer.start();
vector.add(f);
Shape f2 = new Shape(new Area(new Rectangle2D.Double(0, 50, 50, 50)));
f2.translate(200, 400);
f2.timer = new Timer( 10 , taskPerformer);
f2.timer.setInitialDelay(5000);
f2.timer.start();
vector.add(f2);
and my action listener:
Random generator = new Random();
ActionListener taskPerformer = new ActionListener() {
public void actionPerformed(ActionEvent evt) {
//...Perform a task...
for (Shape s : model.getShapes()) {
// Scale object using translate
// once reached ascent drop down
// translate to diffrenet part of the bottom of the screen
// delay its timer
}
update();
//basically repaints
}
};
I'm running into problems that all shapes follow the same timer, and begin to pop up at the same time (no delay) ...
Any suggestions on how to avoid this or if there is a different approach i should try

"I want the object to randomly pop up from the bottom of the screen reach a certain ascent and then fall back down"
See the runnable example below. What I do is pass a radomDelayedStart to the Shape. Every tick of the timer, the randomDelayedStart decreases til it reaches 0, that's when the flag to be drawn in raised. Most of the logic is in the Shape class methods, which are called in the Timers Actionlistener. Everything is done in one Timer. For the ascent, I just used a hard coded 50, but you can also pass a random ascent to the Shape. Let me know if you have any questions. I tried to made the code as clear as possible.
import java.awt.BorderLayout;
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.ArrayList;
import java.util.List;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class RandomShape extends JPanel {
private static final int D_HEIGHT = 500;
private static final int D_WIDTH = 400;
private static final int INCREMENT = 8;
private List<Shape> shapes;
private List<Color> colors;
private Timer timer = null;
public RandomShape() {
colors = createColorList();
shapes = createShapeList();
timer = new Timer(30, new ActionListener() {
public void actionPerformed(ActionEvent e) {
for (Shape shape : shapes) {
shape.move();
shape.decreaseDelay();
repaint();
}
}
});
JButton start = new JButton("Start");
start.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
timer.start();
}
});
JButton reset = new JButton("Reset");
reset.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e) {
shapes = createShapeList();
timer.restart();
}
});
JPanel panel = new JPanel();
panel.add(start);
panel.add(reset);
setLayout(new BorderLayout());
add(panel, BorderLayout.PAGE_START);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
for (Shape shape : shapes) {
shape.drawShape(g);
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(D_WIDTH, D_HEIGHT);
}
private List<Color> createColorList() {
List<Color> list = new ArrayList<>();
list.add(Color.BLUE);
list.add(Color.GREEN);
list.add(Color.ORANGE);
list.add(Color.MAGENTA);
list.add(Color.CYAN);
list.add(Color.PINK);
return list;
}
private List<Shape> createShapeList() {
List<Shape> list = new ArrayList<>();
Random random = new Random();
for (int i = 0; i < 20; i++) {
int randXLoc = random.nextInt(D_WIDTH);
int randomDelayedStart = random.nextInt(100);
int colorIndex = random.nextInt(colors.size());
Color color = colors.get(colorIndex);
list.add(new Shape(randXLoc, randomDelayedStart, color));
}
return list;
}
class Shape {
int randXLoc;
int y = D_HEIGHT;
int randomDelayedStart;
boolean draw = false;
boolean down = false;
Color color;
public Shape(int randXLoc, int randomDelayedStart, Color color) {
this.randXLoc = randXLoc;
this.randomDelayedStart = randomDelayedStart;
this.color = color;
}
public void drawShape(Graphics g) {
if (draw) {
g.setColor(color);
g.fillOval(randXLoc, y, 30, 30);
}
}
public void move() {
if (draw) {
if (y <= 50) {
down = true;
}
if (down) {
y += INCREMENT;
} else {
y -= INCREMENT;
}
}
}
public void decreaseDelay() {
if (randomDelayedStart <= 0) {
draw = true;
} else {
randomDelayedStart -= 1;
}
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JFrame frame = new JFrame();
frame.add(new RandomShape());
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}

How to create multiple objects from the same place in java

I'm trying to make a tower defense game and I'm having trouble making it so that when I click on one of the tower buttons at the bottom and drag to the playing area it creates a new object Tower. I have tried using an arraylist, but everytime I drag to make a new tower the previous tower erases and the new tower stays drawn on the screen.
There are a couple of classes so I will only post the ones I think are relevant. If you need the others I can put them. Sorry in advance for the length of my post.
This is the class where the events are handled
package addison;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.util.ArrayList;
import javax.swing.JPanel;
import javax.swing.Timer;
#SuppressWarnings("serial")
public class Controls extends JPanel implements MouseListener, MouseMotionListener, ActionListener {
Timer timer;
public static int x; //mouse's x pos
public static int y; //mouse's y pos
public static int iteration = 0;
public static String button = ""; //identifies pressed button
public static boolean pressed = false; //true if a button was pressed and not a random space
public static boolean created = false;
public static ArrayList<Tower> tower = new ArrayList<Tower>(); //arraylist of tower objects
public Controls() {
timer = new Timer(5, this); //creates a 5ms timer
timer.start(); //starts timer
addMouseListener(this);
addMouseMotionListener(this);
setFocusable(true);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
Map.paint(g); //draws map
Hud.paint(g); //draws HUD
TextDisplay.paint(g); //displays text
}
public void actionPerformed(ActionEvent e) {
repaint(); //redraws graphics every 5ms
}
#Override
public void mouseClicked(MouseEvent e) {
}
#Override
public void mouseEntered(MouseEvent e) {
}
#Override
public void mouseExited(MouseEvent e) {
}
#Override
public void mousePressed(MouseEvent e) {
if (Hud.getButton()) {
pressed = true;
} else {
pressed = false;
}
System.out.println(pressed);
}
#Override
public void mouseReleased(MouseEvent e) {
x = e.getX(); //gets mouse's x pos
y = e.getY(); //gets mouse's y pos
if (pressed) { // if the button pressed was gun man
tower.add(iteration, new Tower(TextDisplay.description, x, y, 100, 100, 25)); //add a new tower object to the end of the arraylist
System.out.println(tower.get(0).x);
created = true;
pressed = false;
}
iteration++;
}
#Override
public void mouseDragged(MouseEvent e) {
}
#Override
public void mouseMoved(MouseEvent e) {
x = e.getX(); //get mouse's x pos
y = e.getY(); //get mouse;s y pos
if (Hud.getButton()) {
TextDisplay.hovering = true;
} else {
TextDisplay.hovering = false;
}
}
}
package addison;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Rectangle;
this is the class where everything is drawn
public class Map {
public static Rectangle mouse; //location of cursor
public Map() {
}
public static void paint(Graphics g) {
g.setColor(new Color(255, 0, 0)); //makes mouse hit box transparent
mouse = new Rectangle(Controls.x, Controls.y, 5, 5); //create mouse hit box
g.fillRect(mouse.x, mouse.y, mouse.width, mouse.height); //draw mouse hit box
g.drawRect(0, 0, 800, 450); //play area
g.drawRect(0, 0, 800, 500); //options area
if (Controls.created) {
g.fillRect(Controls.tower.get(Controls.iteration).x, Controls.tower.get(0).y, 50, 50);
}
}
}
This is the class where the buttons are:
package addison;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Rectangle;
public class Hud {
public static Rectangle gunman;
public static Rectangle laserTower;
public static Rectangle rocketLauncher;
public static Rectangle emBomb;
public static Rectangle soundGun;
public Hud() {
}
public static void paint(Graphics g) {
gunman = new Rectangle(0, 450, 50, 50); //create gun man button
g.fillRect(gunman.x, gunman.y, gunman.width, gunman.height); //draw gun man button
g.setColor(Color.BLUE);
laserTower = new Rectangle(50, 450, 50, 50); //create laser tower button
g.fillRect(laserTower.x, laserTower.y, laserTower.width, laserTower.height); //draw laser tower button
g.setColor(Color.CYAN);
rocketLauncher = new Rectangle(100, 450, 50, 50); //create rocket launcher tower
g.fillRect(rocketLauncher.x, rocketLauncher.y, rocketLauncher.width, rocketLauncher.height); //draw rocket launcher button
g.setColor(Color.DARK_GRAY);
emBomb = new Rectangle(150, 450, 50, 50); //creates em bomb button
g.fillRect(emBomb.x, emBomb.y, emBomb.width, emBomb.height); //draw em bomb button
g.setColor(Color.GREEN);
soundGun = new Rectangle(200, 450, 50, 50); //create sound gun button
g.fillRect(soundGun.x, soundGun.y, soundGun.width, soundGun.height); //draw sound gun button
}
public static boolean getButton() {
if(Map.mouse.intersects(Hud.gunman)) {
TextDisplay.description = "Gunman";
return true;
} else if (Map.mouse.intersects(Hud.laserTower)) {
TextDisplay.description = "Laser Tower";
return true;
} else if (Map.mouse.intersects(Hud.rocketLauncher)) {
TextDisplay.description = "Rocket Launcher";
return true;
} else if (Map.mouse.intersects(Hud.emBomb)) {
TextDisplay.description = "E.M. Bomb";
return true;
} else if (Map.mouse.intersects(Hud.soundGun)) {
TextDisplay.description = "Sound Gun";
return true;
} else {
TextDisplay.description = "";
return false;
}
}
}
This is the class that makes the Tower objects:
package addison;
public class Tower {
public static String type = ""; //type of tower e.g. gunman or laser tower
public static int x = 0;
public static int y = 0;
public static int range = 0; //tower range
public static int speed = 0; //tower speed
public static int sRange = 0; //tower's shrapnel range
public Tower(String a, int b, int c, int d, int e, int f) {
type = a;
x = b;
y = c;
range = d;
speed = e;
sRange = f;
}
}
Thank you.

because you only paint the tower in the last iteration in the following line:
g.fillRect(Controls.tower.get(Controls.iteration).x, Controls.tower.get(0).y, 50, 50);
You need to paint all towers in the paint function

It seems like you're using Control.iteration as a key into your tower list. However, every time mouseReleased is called (whether a tower is created or not), you're incrementing iteration. This means that the Controls.iteration key in your paint handler will never refer to the newly-created tower. You're also using Controls.tower.get(0).y - why does this differ from the x coord?
I hope I've understood this correctly. If you're just painting the newly-created tower, why not keep a reference to that in Controls? If you're painting them all, you should loop through from 0 to iteration - 1 and move iteration++ inside the if (pressed) block.