What I want to do is once I pressed the button "GO", it will paint/draw 3 ovals with different coordinates. I've tried repainting but seems it doesn't work. It only shows one oval which is the last oval. I want it to stack up and append the ovals.
Here's my code:
import javax.swing.*;
import java.awt.Graphics;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Test extends JFrame implements ActionListener{
JButton button;
int[] itoken;
int x,y;
public Test() {
super("Test");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.setSize(600,500);
this.setVisible(true);
this.setResizable(true);
this.setLayout(null);
button= new JButton("GO");
button.setBounds(500, 100, 50,50);
this.add(button);
button.addActionListener(this);
}
public void actionPerformed(ActionEvent e){
if(e.getSource()==button){
String text= "200 300 250 150 400 100";
String[] token= text.split("\\W");
itoken= new int[token.length];
int i=0;
for (String str : token){
itoken[i++] = Integer.parseInt(str);
}
for(i=0; i<itoken.length; i++)
System.out.println(itoken[i]);
run();
}
}
public void paint(Graphics g) {
super.paint(g);
g.drawOval(x - 5, y - 5, 10, 10);
}
public void run(){
int i=0;
while(i<itoken.length-1){
repaint();
x=itoken[i];
y=itoken[i+1];
i++;
}
}
public static void main(String[] args) {
Test test = new Test();
}
}
Note - I was working on this answer right before you deleted your previous question, so the answer may see a little off in terms of the new code you posted in this question, but it gets you towards the same goal.
Don't initialize everthing in the actionPerformed. You're getting a NullPointerException because paint is called by the frame implicitly before the array is initialized. What I did was create a method to initialize it
int[] iToken = initArray();
...
private int[] initArray() {
String text = "200 300 250 150 400 100";
String[] token = text.split("\\W");
int[] itoken = new int[token.length];
int i = 0;
for (String str : token) {
itoken[i++] = Integer.parseInt(str);
}
return itoken;
}
Don't paint on top level containers like JFrame. Instead us a JPanel or JCompoent and override paintComponent, and override getPreferredSize() in your JPanel so you won't have to set the size of your JFrame. Just pack() it.
Run Swing apps from the Event Dispatch Thread like this
public static void main(String[] args) {
SwingUtilitiies.invokeLater(new Runnable(){
public void run(){
new Test();
}
});
}
You never add your button to the frame.
Don't use a null layout. Use Layout Managers.
Add you components, then call setVisible
Here's the running refactored code
import javax.swing.*;
import java.awt.Graphics;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Test extends JFrame implements ActionListener {
JButton button;
boolean paint = false;
int x, y;
int[] iToken = initArray();
public Test() {
super("Test");
button = new JButton("GO");
button.setBounds(500, 100, 50, 50);
button.addActionListener(this);
add(button, BorderLayout.SOUTH);
add(new DrawPanel());
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.pack();
this.setVisible(true);
this.setResizable(true);
}
public void actionPerformed(ActionEvent e) {
if (e.getSource() == button) {
paint = true;
repaint();
}
}
private int[] initArray() {
String text = "200 300 250 150 400 100";
String[] token = text.split("\\W");
int[] itoken = new int[token.length];
int i = 0;
for (String str : token) {
itoken[i++] = Integer.parseInt(str);
}
return itoken;
}
public class DrawPanel extends JPanel {
public void paintComponent(Graphics g) {
super.paintComponent(g);
if (paint) {
for (int i = 0; i < iToken.length; i += 2) {
x = iToken[i];
y = iToken[i + 1];
g.drawOval(x - 5, y - 5, 10, 10);
}
}
}
public Dimension getPreferredSize() {
return new Dimension(500, 500);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new Test();
}
});
}
}
Related
I've written some code that essentially animates a sequence of images and adds them to a frame when I run the file.
I want to implement a functionality where I can add this animation to two different areas of a JPanel that has a BorderLayout (North and West).
I want to do this using a button but I don't know how to do that. I am new to event handling and layout managers.
How do I go about this?
My code for the animation:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class ImageSequence extends JPanel implements ActionListener {
private ImageSQPanel imageSQPanel;
private static int frameNumber = -1;
private Timer timer;
private void buildUI(Container container, Image[] arrows) {
int fps = 10;
int delay = 1000 / fps;
timer = new Timer(delay, this);
timer.setInitialDelay(0);
timer.setCoalesce(true);
imageSQPanel = new ImageSQPanel(arrows);
container.add(imageSQPanel, BorderLayout.CENTER);
}
private synchronized void startAnimation() {
if (!timer.isRunning()) {
timer.start();
}
}
public void actionPerformed(ActionEvent e) {
frameNumber++;
imageSQPanel.repaint();
}
class ImageSQPanel extends JPanel {
Image arrowAnimation[];
ImageSQPanel(Image[] arrowAnimation) {
this.arrowAnimation = arrowAnimation;
}
//Draw the current frame of animation.
public void paintComponent(Graphics g) {
super.paintComponent(g); //paint background
//Paint the frame into the image.
try {
g.drawImage(arrowAnimation[ImageSequence.frameNumber % 10], 0, 0, this);
} catch (ArrayIndexOutOfBoundsException e) {
//On rare occasions, this method can be called
//when frameNumber is still -1. Do nothing.
}
}
}
//Invoked only when this is run as an application.
public static void main(String[] args) {
Image[] waving = new Image[7];
for (int i = 1; i <= 7; i++) {
waving[i - 1] = Toolkit.getDefaultToolkit().getImage(
"/Users/sarthaksachdeva/Documents/IntelliJ Projects/Animation/src/images/Arrow" + i + ".png");
}
JFrame f = new JFrame("ImageSequenceTimer");
f.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
ImageSequence controller = new ImageSequence();
controller.buildUI(f.getContentPane(), waving);
controller.startAnimation();
f.setSize(new Dimension(200, 200));
f.setVisible(true);
}
}
While using Swing in java, I am trying to move a circle slowly from a starting position to an end position when clicking a button. However, I can't see the circle moving. It just moves from start to end in an instant.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class MyApp {
private int x = 10;
private int y = 10;
private JFrame f;
private MyDraw m;
private JButton b;
public void go() {
f = new JFrame("Moving circle");
b = new JButton("click me to move circle");
m = new MyDraw();
f.add(BorderLayout.SOUTH, b);
f.add(BorderLayout.CENTER, m);
f.setSize(500, 500);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
b.addActionListener(new Bute());
}
public static void main(String[] args) {
MyApp m = new MyApp();
m.go();
}
private class Bute implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
for (int i = 0; i < 150; i++) {
++x;
++y;
m.repaint();
Thread.sleep(50);
}
}
}
private class MyDraw extends JPanel {
#Override
public void paintComponent(Graphics g) {
g.setColor(Color.white);
g.fillRect(0, 0, 500, 500);
g.setColor(Color.red);
g.fillOval(x, y, 40, 40);
}
}
}
I think the problem is with the action listener because when I'm doing it without using button it is working. Any suggestions?
As Andrew Thompson said, calling Thread.sleep() without defining a second thread freezes everything, so the solution is to define and run another thread like so:
class Bute implements ActionListener, Runnable {
//let class implement Runnable interface
Thread t; // define 2nd thread
public void actionPerformed(ActionEvent e) {
t = new Thread(this); //start a new thread
t.start();
}
#Override //override our thread's run() method to do what we want
public void run() { //this is after some java-internal init stuff called by start()
//b.setEnabled(false);
for (int i = 0; i < 150; i++) {
x++;
y++;
m.repaint();
try {
Thread.sleep(50); //let the 2nd thread sleep
} catch (InterruptedException iEx) {
iEx.printStackTrace();
}
}
//b.setEnabled(true);
}
}
The only problem with this solution is that pressing the button multiple times will speed up the circle, but this can be fixed by making the button unclickable during the animation via b.setEnabled(true/false). Not the best solution but it works.
As said in the comments and another answer, don't block the EDT. Thead.sleep(...) will block it, so you have two options:
Create and manage your own (new) thread.
Use a Swing Timer
In this answer I'll be using a Swing Timer, since it's easier to use. I also changed the paintComponent method to use the Shape API and change the button text to start and stop accordingly as well as reusing the same ActionListener for the button and the timer:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class MovingCircle {
private JFrame frame;
private CustomCircle circle;
private Timer timer;
private JButton button;
public static void main(String[] args) {
SwingUtilities.invokeLater(new MovingCircle()::createAndShowGui);
}
private void createAndShowGui() {
frame = new JFrame(this.getClass().getSimpleName());
circle = new CustomCircle(Color.RED);
timer = new Timer(100, listener);
button = new JButton("Start");
button.addActionListener(listener);
circle.setBackground(Color.WHITE);
frame.add(circle);
frame.add(button, BorderLayout.SOUTH);
frame.pack();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
private ActionListener listener = (e -> {
if (!timer.isRunning()) {
timer.start();
button.setText("Stop");
} else {
if (e.getSource().equals(button)) {
timer.stop();
button.setText("Start");
}
}
circle.move(1, 1);
});
#SuppressWarnings("serial")
class CustomCircle extends JPanel {
private Color color;
private int circleX;
private int circleY;
public CustomCircle(Color color) {
this.color = color;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(color);
g2d.fill(new Ellipse2D.Double(circleX, circleY, 50, 50));
}
#Override
public Dimension preferredSize() {
return new Dimension(100, 100);
}
public void move(int xGap, int yGap) {
circleX += xGap;
circleY += yGap;
revalidate();
repaint();
}
public int getCircleX() {
return circleX;
}
public void setCircleX(int circleX) {
this.circleX = circleX;
}
public int getCircleY() {
return circleY;
}
public void setCircleY(int circleY) {
this.circleY = circleY;
}
}
}
I'm sorry, I can't post a GIF as I wanted but this example runs as expected.
I try to write a code to draw a Oval run from the top left down to the bottom right. But when I run to program, it show the blank screen on app.
Why is this happening?
Here is my code:
import javax.swing.*;
import java.awt.*;
public class SimpleAnimation {
int x = 70;
int y = 70;
public static void main(String[] arg){
SimpleAnimation gui = new SimpleAnimation();
gui.go();
}
public void go(){
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
MyDrawPanel drawPanel = new MyDrawPanel();
frame.getContentPane().add(drawPanel);
frame.setSize(300, 300);
frame.setVisible(true);
for (int i = 0; i < 130; i++){
x++;
y++;
drawPanel.repaint();
try{
Thread.sleep(50);
} catch(Exception ex){}
}
} // close go() method
class MyDrawPanel extends JPanel{
#Override
public void paintComponents(Graphics g) {
g.setColor(Color.green);
g.fillOval(x, y, 40, 40);
}
} // close inner class
} // close outer class
You should Override paintComponent() instead of paintComponents().
So change the public void paintComponents() {...} to public void paintComponent() {...}
But just for the hint:
Try to use Timers instead of Threads. Always try not to mess with the swing thread. In your case you can use javax.swing.Timer to call the repaint in 50 ms intervals:
counter = 0;
t = new Timer(50, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if(counter>=130)
t.stop();
counter++;
x++;
y++;
drawPanel.repaint();
}
});
t.start();
javax.swing.Timer t and int counter are member variables for your class.
Good Luck.
You are not calling super.paintComponent(g); and also you need to call paintComponents rather than repaint method. Please try it with below code. I hope it helps :)
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class SimpleAnimation {
int x = 70;
int y = 70;
public static void main(String[] arg) {
SimpleAnimation gui = new SimpleAnimation();
gui.go();
}
public void go() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
MyDrawPanel drawPanel = new MyDrawPanel();
frame.getContentPane().add(drawPanel);
frame.setSize(300, 300);
frame.setVisible(true);
for (int i = 0; i < 130; i++) {
x++;
y++;
drawPanel.paintComponents(drawPanel.getGraphics());
try {
Thread.sleep(50);
} catch (Exception ex) {
}
}
} // close go() method
class MyDrawPanel extends JPanel {
#Override
public void paintComponents(Graphics g) {
// TODO Auto-generated method stub
super.paintComponent(g);
g.drawOval(50, 50, 50, 50);
g.setColor(Color.green);
g.fillOval(x, y, 40, 40);
}
} // close inner class
} // close outer class
I am doing a java assignment for next Saturday.
Its going really well, however I'm struggling with one section.
Here I want to reveal a set of numbers in a String, one at a time.
I tried slowing down the loop with 'Thread.sleep(1000);'
however nothing is displaying until the thread is finished
the following is a section of the graphics class where the problem is occuring
is there something I'm missing?
public void paint(Graphics g)
{
setSize(550, 300);
//this draws all the random numbers, revealing the ans to the user
if (revealNum == 0)
{
g.setColor(Color.BLUE);
g.drawString(randomNumber, 20, 20); //draw String ("the String", x, y)
}
//this reveals the numbers 1 by 1 to the user at the start of the game
if (revealNum==1)
{
for (int x = 0; x < limit; x++)
{
g.setColor(Color.BLUE);
g.drawString(""+x, 20, 20); //draw String ("the String", x, y)
try{
Thread.sleep(1000);
}catch(InterruptedException ex){
System.out.print("Error");
}
repaint();
}
//slow down the loop to show the user
}
Since yours is a GUI, calling Thread.sleep will put the entire app to sleep. Instead use a Swing Timer. Inside the Timer's ActionListener, add another letter to the displayed String, and then stop the Timer via the stop() method once the String is complete.
e.g.,
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import javax.swing.*;
public class SimpleAnimation extends JPanel {
public static final int TIMER_DELAY = 1000;
private JTextField textField = new JTextField(10);
private JLabel displayLabel = new JLabel("", SwingConstants.CENTER);
public SimpleAnimation() {
Action btnAction = new DoItBtnAction("Do It!", KeyEvent.VK_D);
JPanel topPanel = new JPanel();
topPanel.add(textField);
topPanel.add(new JButton(btnAction));
textField.addActionListener(btnAction);
setLayout(new GridLayout(2, 1));
add(topPanel);
add(displayLabel);
}
private class DoItBtnAction extends AbstractAction {
private String textFieldText = "";
public DoItBtnAction(String name, int mnemonic) {
super(name);
putValue(MNEMONIC_KEY, mnemonic);
}
#Override
public void actionPerformed(ActionEvent e) {
displayLabel.setText("");
setEnabled(false);
textFieldText = textField.getText();
new Timer(TIMER_DELAY, new ActionListener() {
private int i = 0;
#Override
public void actionPerformed(ActionEvent e) {
if (i >= textFieldText.length()) {
((Timer) e.getSource()).stop();
DoItBtnAction.this.setEnabled(true);
} else {
displayLabel.setText(displayLabel.getText() + textFieldText.charAt(i));
i++;
}
}
}).start();
}
}
private static void createAndShowGui() {
JFrame frame = new JFrame("SimpleAnimation");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new SimpleAnimation());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
Also,
If yours is a Swing GUI, it would be easier to display your text in a JLabel or a JTextField rather than trying to paint it on the GUI.
If this is Swing, don't override paint(Graphics g) but rather the paintComponent(Graphics g) method of a JPanel or JComponent.
You should use a javax.swing.Timer
Here is an example
JLabel l = ...;
Timer t = new Timer(1000, new ActionListener() {
public void actionPerformed(ActionEvent ae) {
if (l.getText().equals("1")) l.setText("2");
else if (l.getText().equals("2)) l.setText("1");
}
});
I have the following program which has some very strange and unwanted behavior when it runs. Its supposed to have two buttons, "Start" and "Stop, but when I click "Start" another button shows up right below "Start". Here's a print screen of what I'm talking about:
What am I doing wrong and how do I fix this ugly problem?
Here's the code:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.Random;
public class TwoButtonsTest {
JFrame frame;
Timer timer;
boolean isClicked;
public static void main(String[] args) {
TwoButtonsTest test = new TwoButtonsTest();
test.go();
}
public void go() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500, 500);
JButton startButton = new JButton("Start");
startButton.addActionListener(new StartListener());
JButton stopButton = new JButton("Stop");
stopButton.addActionListener(new StopListener());
final DrawPanel myDraw = new DrawPanel();
frame.getContentPane().add(BorderLayout.CENTER, myDraw);
frame.getContentPane().add(BorderLayout.NORTH, startButton);
frame.getContentPane().add(BorderLayout.SOUTH, stopButton);
frame.setVisible(true);
timer = new Timer(50, new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
myDraw.repaint();
}
});
}
class StartListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
//needs to be implemented
if(!isClicked) {
}
isClicked = true;
timer.start();
}
}
class StopListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
//needs to be implemented
timer.stop();
isClicked = false;
}
}
class DrawPanel extends JPanel {
public void paintComponent(Graphics g) {
int red = (int)(Math.random()*256);
int blue = (int)(Math.random()*256);
int green = (int)(Math.random()*256);
g.setColor(new Color(red, blue, green));
Random rand = new Random();
// following 4 lines make sure the rect stays within the frame
int ht = rand.nextInt(getHeight());
int wd = rand.nextInt(getWidth());
int x = rand.nextInt(getWidth()-wd);
int y = rand.nextInt(getHeight()-ht);
g.fillRect(x,y,wd,ht);
}
} // close inner class
}
Also I'm trying to get the Start button to do two things. One is to of course start the animation but when the Stop button is pressed and I press Start again, I want it to clean the screen so to speak and start the animation again a new. Any tips on that?
You do not call super.paintComponent(Graphics g) in overriden paintComponent(..) method which you should in order to honor the paint chain and thus the painting of other components.
This call should also be the first call within the method:
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
//do painting here
}
A probem might arise that drawings are not persistent. You must than have a way to store drawings and redraw every time. The most common is an ArrayList which will hold objects to be drawn (thus you cann add to the list remove etc), you would than iterate over the list and redraw each object in paintComponent. See my answer here for an example.
Also please remember to create and manipulate Swing components on Event Dispatch Thread :
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
//create UI and components here
}
});
Dont call setSize(..) on JFrame rather override getPreferredSize() of JPanel and return an appropriate height which fits all components, than call JFrame#pack() before setting JFrame visible (but after adding all components).
No need for getContentPane().add(..) as of Java 6+ add(..) defaults to contentPane
Do not re declare Random i.e Random r=new Random() each time paintComponent is called as this will make the distributions of the values less random rather initiate it once when class is created and call methods on the instance
Here is the fixed code (with above fixes implemented):
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import java.util.Random;
import javax.swing.*;
public class TwoButtonsTest {
JFrame frame;
Timer timer;
boolean isClicked;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
TwoButtonsTest test = new TwoButtonsTest();
test.go();
}
});
}
final DrawPanel myDraw = new DrawPanel();
public void go() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JButton startButton = new JButton("Start");
startButton.addActionListener(new StartListener());
JButton stopButton = new JButton("Stop");
stopButton.addActionListener(new StopListener());
frame.add(myDraw, BorderLayout.CENTER);
frame.add(startButton, BorderLayout.NORTH);
frame.add(stopButton, BorderLayout.SOUTH);
frame.pack();
frame.setVisible(true);
timer = new Timer(50, new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
myDraw.repaint();
}
});
}
class StartListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent e) {
//needs to be implemented
if (!isClicked) {
}
myDraw.clearRects();
isClicked = true;
timer.start();
}
}
class StopListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
//needs to be implemented
timer.stop();
isClicked = false;
}
}
class DrawPanel extends JPanel {
private ArrayList<MyRectangle> rects = new ArrayList<>();
private Random rand = new Random();
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
addRect();
for (MyRectangle r : rects) {
g.setColor(r.getColor());
g.fillRect(r.x, r.y, r.width, r.height);
}
}
#Override
public Dimension getPreferredSize() {
return new Dimension(500, 500);
}
public void clearRects() {
rects.clear();
}
public void addRect() {
// following 4 lines make sure the rect stays within the frame
int ht = rand.nextInt(getHeight());
int wd = rand.nextInt(getWidth());
int x = rand.nextInt(getWidth() - wd);
int y = rand.nextInt(getHeight() - ht);
int red = (int) (Math.random() * 256);
int blue = (int) (Math.random() * 256);
int green = (int) (Math.random() * 256);
rects.add(new MyRectangle(x, y, wd, ht, new Color(red, blue, green)));
}
} // close inner class
}
class MyRectangle extends Rectangle {
Color color;
public MyRectangle(int x, int y, int w, int h, Color c) {
super(x, y, w, h);
this.color = c;
}
public Color getColor() {
return color;
}
}
I wish I could offer a solution, but as of yet I haven't found one. I can tell you the root of the "problem" here lies in the way you are drawing the Center section of your BorderLayout. You are overriding the whole paintComponent() function for this program and having whatever it creates put into the Center of your BoarderLayout. In this case, each time you click a button, the program calls the repaint to draw the image of a clicked button, but since you have also added ANY of the drawn objects to the Center panel, it also is drawn there. Since this specific repaint doesn't specify a location, it goes in the upper left corner.
I fixed your button problem on my Windows XP computer by invoking SwingUtilities.
I formatted your Java code.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
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 TwoButtonsTest implements Runnable {
JFrame frame;
Timer timer;
boolean isClicked;
public static void main(String[] args) {
SwingUtilities.invokeLater(new TwoButtonsTest());
}
#Override
public void run() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500, 500);
JButton startButton = new JButton("Start");
startButton.addActionListener(new StartListener());
JButton stopButton = new JButton("Stop");
stopButton.addActionListener(new StopListener());
final DrawPanel myDraw = new DrawPanel();
frame.getContentPane().add(BorderLayout.CENTER, myDraw);
frame.getContentPane().add(BorderLayout.NORTH, startButton);
frame.getContentPane().add(BorderLayout.SOUTH, stopButton);
frame.setVisible(true);
timer = new Timer(50, new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
myDraw.repaint();
}
});
}
class StartListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
// needs to be implemented
if (!isClicked) {
}
isClicked = true;
timer.start();
}
}
class StopListener implements ActionListener {
public void actionPerformed(ActionEvent e) {
// needs to be implemented
timer.stop();
isClicked = false;
}
}
class DrawPanel extends JPanel {
#Override
public void paintComponent(Graphics g) {
int red = (int) (Math.random() * 256);
int blue = (int) (Math.random() * 256);
int green = (int) (Math.random() * 256);
g.setColor(new Color(red, blue, green));
Random rand = new Random();
// following 4 lines make sure the rect stays within the frame
int ht = rand.nextInt(getHeight());
int wd = rand.nextInt(getWidth());
int x = rand.nextInt(getWidth() - wd);
int y = rand.nextInt(getHeight() - ht);
g.fillRect(x, y, wd, ht);
}
} // close inner class
}
To clean the screen when you press the Start button, you're going to have to add some methods to your DrawPanel class.
Here's one way to do it.
class DrawPanel extends JPanel {
protected boolean eraseCanvas;
public void setEraseCanvas(boolean eraseCanvas) {
this.eraseCanvas = eraseCanvas;
}
#Override
public void paintComponent(Graphics g) {
if (eraseCanvas) {
g.setColor(Color.WHITE);
g.fillRect(0, 0, getWidth(), getHeight());
} else {
int red = (int) (Math.random() * 256);
int blue = (int) (Math.random() * 256);
int green = (int) (Math.random() * 256);
g.setColor(new Color(red, blue, green));
Random rand = new Random();
// following 4 lines make sure the rect stays within the frame
int ht = rand.nextInt(getHeight());
int wd = rand.nextInt(getWidth());
int x = rand.nextInt(getWidth() - wd);
int y = rand.nextInt(getHeight() - ht);
g.fillRect(x, y, wd, ht);
}
}
} // close inner class