Tutorials : Java by Example : Section 2 :
Section Two Contents
Introducing the Operators
Methods With and Without a Return Value
Using Methods and Basic Mouse Funtions

Operators and Methods

Using Methods and Basic Mouse Funtions - Con't

Here you can see how to use the Java methods for determining whether the mouse cursor is inside or outside the applet (mouseEnter and mouseExit), and how to process mouse clicks inside the applet.

The expression "clicks=clicks+1;", which increments the variable "clicks", is usually written in short form: "clicks++", which we will also do from now on. The expression "clicks+=2" would increment it with 2 instead of 1.

//Sourcecode 

import java.awt.*;
import java.applet.*;

public class Project5 extends Applet
{
        int mouseX, mouseY, clicks;
        boolean mouseIn;

        public boolean mouseDown(Event evt,int x,int y)
        {
                clicks=clicks+1;
                mouseX=x;
                mouseY=y;

                repaint();

                return true;
        }

        public boolean mouseEnter(Event evt,int x,int y)
        {
                mouseIn=true;
                repaint();

                return true;
        }

        public boolean mouseExit(Event evt,int x,int y)
        {
                mouseIn=false;
                repaint();

                return true;
        }

        public void paint(Graphics g)
        {
                g.setFont(new Font("Helvetica",Font.PLAIN,13));

                g.setColor(Color.black);
                g.drawString("Mouse clicks: "+clicks, 100,80);
                g.drawString("Mouseclick coordinates: x="+mouseX+", y="+mouseY, 40,110);

                if(mouseIn==true)
                {
                        g.setColor(Color.red);
                        g.drawString("Mouse is inside the applet",70,180);
                }
                else
                {
                        g.setColor(Color.blue);
                        g.drawString("Mouse is outside the applet",70,180);
                }
        }
}

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