Handling Errors in Java Programming

// The “name-of-application” class

import java.awt.*;

import hsa.Console;

public class name-of-application

{

static Console c;

static public void main (String [] args)

{

c = new Console ();

your program goes here

} // main method

any user-defined methods go here

} // name-of-application class

// The “GreenOval” class

import java.awt.*;

import hsa.Console;

public class GreenOval

{

static Console c;

static public void main (String [] args)

{

c = new Console ();

c.setColor (Color.green);

c.fillOval (0, 0, 100, 200);

} // main method

} // GreenOval class

// The “GreenOval” class

import java.awt.*;

import hsa.Console;

public class GreenOval

{

static Console c;

static public void main (String [] args)

{

c = new Console ();

c.setColor (Color.green);

c.fillOval (0, 0, 100, 200);

} // main method

} // GreenOval class

delete the semicolon

// The “GreenOval” class

import java.awt.*;

import hsa.Console;

public class GreenOval

{

static Console c;

static public void main (String [] args)

{

c = new Console ();

c.setColor (Color.green);

c.fillOval (0, 0, 100, 200);

} // main method

} // GreenOval class

delete c.

// The “GreenOval” class

import java.awt.*;

import hsa.Console;

public class GreenOval

{

static Console c;

static public void main (String [] args)

{

c = new Console ();

c.setColor (Color.green);

c.fillOval (0, 0, 100, 200);

} // main method

} // GreenOval class

delete the close curly brace

// The “GreenOval” class

import java.awt.*;

import hsa.Console;

public class GreenOval

{

static Console c;

static public void main (String [] args)

{

c = new Console ();

c.setColor (Color.green);

c.fillOval (0, 0, 100, 200);

} // main method

} // GreenOval class

uppercase the c

Multiple errors

There are actually 4 errors

lowercase c

missing semicolonc. is missing

main mispelled

Debugging Activity

• Before your program is compiling and running correctly

• Put in 2 simple errors

• Compile

• Swap seats with a classmate

• Debug each other’s “buggy” programs

FaceWrite a program that produces a picture of a face. It must consist of at least 4 different colors and the following: head, eyes, nose, mouth. Name this class Face.

graphics in java.awt.*…

void drawLinedrawLine (int x1, int y1, int x2, int y2)

void drawOvaldrawOval (int x, int y, int width, int height)

…

graphics in hsa.console.*void clearRectclearRect (int x, int y, int width, int

height)

…

void drawArcdrawArc (int x, int y, int width, int height, int startAngle, int arcAngle)

drawLine (int x1, int y1, int x2, int y2);

fillOval (int x, int y, int width, int height);

(x,y) -------------------width------------------------

Height

•Start a new hsa console app and call it Face}//main methodstatic public void circle(int xc, int yc, int radius, Color clr) { int width = radius * 2; int height = radius * 2; int x = xc - radius; int y = yc - radius; c.setColor(clr); c.drawOval(x,y,width,height); }//circle method

public static void main (String[] args) { c = new Console (); int xc = c.getWidth() /2; int yc = c.getHeight() /2; int radius = c.getHeight() /2; circle(xc, yc, radius, Color.red);

c.setColor(Color.black); c.drawLine(250,300,400,300);

int xe = c.getWidth() /3; int ye = c.getHeight() /4; int e_rad = c.getHeight() /50; circle(xe, ye, e_rad, Color.blue);

int ae = xc + (xe / 2); int be = c.getHeight() /4; int a_rad = c.getHeight() / 50; circle(ae, be, a_rad, Color.orange); int ayn = c.maxy () / 2; int axn = c.maxx () / 2; int rad = 16; circle(axn, ayn, rad, Color.green); } // main method