Jing Liang

Sorry forgot to wrap it with CODE on the first post.

import java.applet.*; import java.awt.*; import java.awt.event.*; import javax.swing.*; import java.awt.geom.*; public class Tanks extends JApplet { public static final int WIDTH = 400; public static final int HEIGHT = 400; private JButton button1; private PaintSurface currentSurface = new PaintSurface(); public Tanks() { this.add(currentSurface,BorderLayout.CENTER); ButtonListener b1 = new ButtonListener(); JPanel panel = new JPanel(); [B]panel.setBackground(Color.white); currentSurface.setBackground(Color.white);[/B]button1 = new JButton("Start"); button1.addActionListener(b1); panel.add(button1); this.add(panel,BorderLayout.NORTH); } public void init() { this.setSize(WIDTH, HEIGHT); this.setVisible(true); } private class ButtonListener implements ActionListener { public void actionPerformed(ActionEvent e) { if(e.getActionCommand() == "Start") { currentSurface.figure="Start"; repaint(); } } } } class AnimationThread extends Thread { JApplet c; public AnimationThread(JApplet c) { this.c = c; } public void run() { } } class PaintSurface extends JComponent { String figure; public PaintSurface() { } public void paint(Graphics g) { Graphics2D g2 = (Graphics2D)g; g2.setRenderingHint( RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); if(figure=="Start") { Shape s = new Ellipse2D.Float(20,50,250,150); g2.setPaint(Color.BLACK); g2.draw(s); } } }

In my JApplet, I am able to change the background color of the panel but not the currentSurface which is an instance of PaintSurface. Could someone please help me out? Many thanks

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.geom.*;

public class Tanks extends JApplet
{
public static final int WIDTH = 400;
public static final int HEIGHT = 400;
private JButton button1;
private PaintSurface currentSurface = new PaintSurface();

public Tanks()
{
this.add(currentSurface,BorderLayout.CENTER);
ButtonListener b1 = new ButtonListener();
JPanel panel = new JPanel();
panel.setBackground(Color.white);
currentSurface.setBackground(Color.white);
button1 = new JButton("Start");
button1.addActionListener(b1);
panel.add(button1);
this.add(panel,BorderLayout.NORTH);

}


public void init()
{
this.setSize(WIDTH, HEIGHT);

this.setVisible(true);


}


private class ButtonListener implements ActionListener
{


public void actionPerformed(ActionEvent e)
{
if(e.getActionCommand() == "Start")
{
currentSurface.figure="Start";
repaint();
}
}


}
}


class AnimationThread extends Thread
{
JApplet c;

public AnimationThread(JApplet c)
{
this.c = c;
}

public void run()
{

}
}


class PaintSurface extends JComponent
{
String figure;


public PaintSurface()
{

}

public void paint(Graphics g)
{
Graphics2D g2 = (Graphics2D)g;

g2.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);



if(figure=="Start")
{
Shape s = new Ellipse2D.Float(20,50,250,150);
g2.setPaint(Color.BLACK);
g2.draw(s);

}


}
}

Thanks

How do I draw(show) the ellipse only if the start button is pressed?
Thanks in advance

import java.applet.*; import java.awt.*; import java.awt.event.*; import javax.swing.*; import java.awt.geom.*; public class Tanks extends JApplet { public static final int WIDTH = 400; public static final int HEIGHT = 400; private JButton button1; public Tanks() { this.add(new PaintSurface(),BorderLayout.CENTER); ButtonListener b1 = new ButtonListener(); JPanel panel = new JPanel(); button1 = new JButton("Start"); button1.addActionListener(b1); panel.add(button1); this.add(panel,BorderLayout.NORTH); } public void init() { this.setSize(WIDTH, HEIGHT); this.setVisible(true); } private class ButtonListener implements ActionListener { public void actionPerformed(ActionEvent e) { if(e.getSource() == button1) { repaint(); } } } } class AnimationThread extends Thread { JApplet c; public AnimationThread(JApplet c) { this.c = c; } public void run() { } } class PaintSurface extends JComponent { public PaintSurface() { } public void paint(Graphics g) { Graphics2D g2 = (Graphics2D)g; g2.setRenderingHint( RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); Shape s = new Ellipse2D.Float(20,50,250,150); g2.setPaint(Color.BLACK); g2.draw(s); } }

The button shows up when I add the button at the init() BorderLayout.NORTH

It works. Thanks Eric

My codes able to draw the ellipse but not the button("Start"). I added the button to the JComponent. Could someone tell me what I did wrong and help me out? Thanks in advance

import java.applet.*; import java.awt.*; import java.awt.event.*; import javax.swing.*; import java.awt.geom.*; public class Tanks extends JApplet { public static final int WIDTH = 400; public static final int HEIGHT = 400; public void init() { this.setSize(WIDTH, HEIGHT); this.add(new PaintSurface(), BorderLayout.CENTER); } } class AnimationThread extends Thread { JApplet c; public AnimationThread(JApplet c) { this.c = c; } public void run() { } } class PaintSurface extends JComponent { private JButton button1; public PaintSurface() { [B]JPanel panel = new JPanel(); button1 = new JButton("Start"); panel.add(button1); this.add(panel);[/B] } public void paint(Graphics g) { Graphics2D g2 = (Graphics2D)g; g2.setRenderingHint( RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); Shape s = new Ellipse2D.Float(20,50,250,150); g2.setPaint(Color.BLACK); g2.draw(s); } }

Thank you very much

I have question when to create an object.
Examples:
when we use the Math methods, we write Math.random(), Math.pow()

So why we need to create an instance when we use the Scanner methods
Scanner sc = new Scanner(System.in); int i = sc.nextInt();

How do I know when to create an instance or not?

Thanks in advance

Problem solved thanks guys

Hello guys,

I couldn't fix this NPE. Please Help. Thanks
In my playGame() method, I have if(temp1==temp2) { repaint(); } else {repaint(); t= new Timer(2000, new GuessGame()); t.setRepeats(false); t.start(); }

I receive NPE from t.start();

Here are my program
import java.awt.*; import java.applet.Applet; import java.awt.event.*; import javax.swing.*; public class GuessGame extends Applet implements ActionListener, MouseListener { int x,y; Box [][] boxes = new Box[4][4]; Box boxChoice; Button newGame; Timer t; int col; int row; int initialBoxX = 50; int initialBoxY = 50; int width = 50; int height = 50; Graphics g; int counter=0; Color itemp, temp1, temp2; int row1, col1, row2, col2; public void init() { newGame = new Button("New Game"); add(newGame); newGame.addActionListener(this); addMouseListener(this); setBackground(Color.white); setNewGame(); } public void setNewGame() { int chosenColors[] = {0,0,0,0,0,0,0,0}; int rint; int localX, localY; for(int col = 0; col <=3; col++) { for(int row = 0; row<=3; row++) { localY = initialBoxY + row*height; localX = initialBoxX + col*width; rint = (int)(Math.random() * 8); while (chosenColors[rint] >= 2) { rint = (int)(Math.random() * 8); } chosenColors[rint] = chosenColors[rint] +1; Color colorChoices[] = {Color.red,Color.blue,Color.cyan, Color.green, Color.magenta,Color.pink,Color.orange, Color.yellow}; boxes[row][col] = new Box(localX, localY, height, width, colorChoices[rint]); } } repaint(); } public void paint(Graphics g) { displayGame(g); } public void displayGame(Graphics g) { // go to each box and display it. for (int i = 0; i <= 3; i++) { for (int j = 0; j <= 3; j++) { //System.out.println("display coordinates: row "+i+" column "+j); boxes[i][j].display(g); } } // now make the solid lines around the boxes } public void playGame() { if(counter==3) { boxes[row1][col1].showColor=false; counter=0; repaint(); } if(counter==1) { temp1=itemp; row1=row; col1=col; repaint(); } if(counter==2) { row2=row; col2=col; if(row1==row2 && col1==col2) { counter=1; return; } else { temp2=itemp; counter=0; } if(temp1==temp2) { repaint(); } else {repaint(); t= new Timer(2000, new GuessGame()); t.setRepeats(false); t.start(); } } } public void actionPerformed(ActionEvent event) { if(event.getSource()==newGame) { setNewGame(); } else { boxes[row1][col1].showColor=false; boxes[row2][col2].showColor=false; repaint(); } } public void mouseClicked(MouseEvent e) { } public void mouseEntered(MouseEvent e) { } public void mouseExited(MouseEvent e) { } public void mousePressed(MouseEvent e) { } public void mouseReleased(MouseEvent e) { x=e.getX(); y=e.getY(); if((x>=initialBoxX && x<=4*width+initialBoxX)&&(y>=initialBoxY && y<=4*height+initialBoxY)) { int rowSubscript = (y - initialBoxY)/height; int colSubscript = (x - initialBoxX)/width; this.row=rowSubscript; this.col=colSubscript; if(boxes[rowSubscript][colSubscript].showColor==true) { counter=3; playGame(); } else { counter++; itemp = boxes[rowSubscript][colSubscript].boxColor; boxes[rowSubscript][colSubscript].showColor=true; playGame(); } } else { } } class Box { int x, y; int width; int height; Color boxColor; Graphics g; boolean showColor = false; // this is a flag - it will later tell the box // if it has been clicked or not public Box(int X1,int Y1,int h ,int w, Color myColor) { x = X1; y = Y1; height = h; width = w; boxColor = myColor; } public void display(Graphics graph) { g = graph; if (showColor == false) { g.setColor(Color.gray); g.fillRect(x, y, height, width); } else { g.setColor(boxColor); g.fillRect(x, y, height, width); } } public void picked() { boxes[row][col].showColor=true; } } } class Ticker implements ActionListener { GuessGame timer=new GuessGame(); boolean tick = true; public void actionPerformed(ActionEvent eve) { timer.repaint(); } }

Thanks Michael

Thanks Ernest

The javax.swing.Timer will call my method at every interval time but I only want it delay the time to call my method once. Do you know how could I fix this?

Hi guys,

I am looking for a method or class that can delay calling my method at a defined interval. Does anyone have an idea? Thanks

I don't want Box to be inner class, so how can call on boxes[i][j] and set its showColor variables from the picked() method? thanks