Java determine pixel was clicked or not

Complete source code below just a simple java program that will determine if you was clicked or not on 8 black dots. If you was clicked , program will inform you that the dot was clicked.I hope you can see all 8 black dots that i mean because it is too small and try click on it to see what happen.

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COMPLETE SOURCE CODE FOR : JavaDeterminePixelClicked.java
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import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class JavaDeterminePixelClicked extends Canvas implements MouseListener
{
boolean [] con={ false,false,false,false,false,false,false,false };
int[][]coor=new int[8][2];
Robot r;

public JavaDeterminePixelClicked()
{
addMouseListener(this);
try
{
r=new Robot();
}
catch(Exception exception)
{
exception.printStackTrace();
}

JFrame a=new JFrame(">>>>>TRY CLICK AT BLACK DOT<<<<<");
a.getContentPane().add(this,BorderLayout.CENTER);
a.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
a.setSize(500,500);
a.setLocationRelativeTo(null);
a.setVisible(true);
}

public void paint(Graphics g)
{
setBackground( new Color (255,255,255) );
super.paint(g);
g.setColor( new Color (0,0,0) );
g.drawLine(30,30,30,30);
g.drawLine(40,40,40,40);
g.drawLine(50,50,50,50);
g.drawLine(60,60,60,60);
g.drawLine(70,70,70,70);
g.drawLine(80,80,80,80);
g.drawLine(90,90,90,90);
g.drawLine(100,100,100,100);
}

public void mouseClicked(MouseEvent event)
{
Color temp=r.getPixelColor(event.getLocationOnScreen().x,event.getLocationOnScreen().y);
if(temp.getRed()==0&&temp.getGreen()==0&&temp.getBlue()==0)
{
int upperLeftX=getLocationOnScreen().x;
int upperLeftY=getLocationOnScreen().y;
int currentX=event.getLocationOnScreen().x;
int currentY=event.getLocationOnScreen().y;
if(currentX-upperLeftX==30&¤tY-upperLeftY==30)
{
if(con[0]==false)
{
con[0]=true;
}
else
{
JOptionPane.showMessageDialog(null,"This point was clicked");
}
}
if(currentX-upperLeftX==40&¤tY-upperLeftY==40)
{
if(con[1]==false)
{
con[1]=true;
}
else
{
JOptionPane.showMessageDialog(null,"This point was clicked");
}
}
if(currentX-upperLeftX==50&¤tY-upperLeftY==50)
{
if(con[2]==false)
{
con[2]=true;
}
else
{
JOptionPane.showMessageDialog(null,"This point was clicked");
}
}
if(currentX-upperLeftX==60&¤tY-upperLeftY==60)
{
if(con[3]==false)
{
con[3]=true;
}
else
{
JOptionPane.showMessageDialog(null,"This point was clicked");
}
}
if(currentX-upperLeftX==70&¤tY-upperLeftY==70)
{
if(con[4]==false)
{
con[4]=true;
}
else
{
JOptionPane.showMessageDialog(null,"This point was clicked");
}
}
if(currentX-upperLeftX==80&¤tY-upperLeftY==80)
{
if(con[5]==false)
{
con[5]=true;
}
else
{
JOptionPane.showMessageDialog(null,"This point was clicked");
}
}
if(currentX-upperLeftX==90&¤tY-upperLeftY==90)
{
if(con[6]==false)
{
con[6]=true;
}
else
{
JOptionPane.showMessageDialog(null,"This point was clicked");
}
}
if(currentX-upperLeftX==100&¤tY-upperLeftY==100)
{
if(con[7]==false)
{
con[7]=true;
}
else
{
JOptionPane.showMessageDialog(null,"This point was clicked");
}
}
}
}

public void mouseEntered(MouseEvent event)
{
//NOTHING
}

public void mouseExited(MouseEvent event)
{
//NOTHING
}

public void mousePressed(MouseEvent event)
{
//NOTHING
}

public void mouseReleased(MouseEvent event)
{
//NOTHING
}

public static void main(String[]args)
{
JavaDeterminePixelClicked jdpc = new JavaDeterminePixelClicked ();
}
}


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JUST COMPILE AND EXECUTE IT
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