Solution for Step 1: Textual Output

/**

* Name (s ):

* ID ( s ):

* Section (s ):

*

* CS100J Program 2 - Fall 2000

*

* Draws a series of polygons based on a list of coordinates provided by the user. Computes

* the number of edges for each polygon, as well as the area of a bounding box.

*/

public class GraphicsPolygon {

/**

* The main method.

* @param args Command line argument list

*/

public static void main( String args[] )

{

// current number of Polygons

int numOfPolygons = 0;

// number of edges in latest polygon

int numOfEdges = 0;

// Initialize Text object in to read from standard input.

TokenReader in = new TokenReader(System.in);

// Starting coordinates for current polygon

int firstX, firstY;

// Coordinates of xMin, yMin, xMax, and yMax for current polygon

int xMin, yMin, xMax, yMax;

// Coordinates of latest point

int x, y;

System.out.println( "Enter the coordinates: " );

xMin = xMax = firstX = x = in.readInt();

yMin = yMax = firstY = y = in.readInt();

System.out.println();

// Continue to draw lines and polygons until the user enters -1 -1

while ( x >=0 && y >=0 )

{

// previous point

int xPrev = x;

int yPrev = y;

x = in.readInt();

y = in.readInt();

numOfEdges++;

// Update minimum and maximum variables if necessary

if ( x < xMin )

xMin = x;

else if ( x > xMax )

xMax = x;

if ( y < yMin )

yMin = y;

else if (y > yMax )

yMax = y;

// Draw a line to the current point only if it is not -1 -1

if ( x >=0 && y >=0 )

System.out.println("Drawing line from <" + xPrev + ", " +

+ yPrev + "> to <" + x + ", " + y + ">");

if ( x == firstX && y == firstY )

{

// Print message indicating box has closed.

System.out.println("Polygon #" + (++numOfPolygons) + " has " +

+ numOfEdges + " edges." );

System.out.println("Drawing rectangle with top-left corner <" +

+ xMin + ", "+ yMin + ">.");

System.out.println("Bounding box area is " +

+ ( ( xMax - xMin )*( yMax - yMin ) ) +".\n");

// Reset variables for next polygon

xMin = xMax = firstX = x = in.readInt();

yMin = yMax = firstY = y = in.readInt();

numOfEdges = 0;

}

}// end while

System.out.println("Total number of polygons: " + numOfPolygons );

}

}

/*

SAMPLE OUTPUT:

Enter the coordinates:

10 10 50 15 5 20 10 10 50 50 60 60 55 75 50 50 -1 -1

Drawing line from <10, 10> to <50, 15>

Drawing line from <50, 15> to <5, 20>

Drawing line from <5, 20> to <10, 10>

Polygon #1 has 3 edges.

Drawing rectangle with top-left corner <5, 10>.

Bounding box area is 450.

Drawing line from <50, 50> to <60, 60>

Drawing line from <60, 60> to <55, 75>

Drawing line from <55, 75> to <50, 50>

Polygon #2 has 3 edges.

Drawing rectangle with top-left corner <50, 50>.

Bounding box area is 250.

Total number of polygons: 2

*/

Solution for Step 2: Graphical Output

import java.awt.*;

import java.io.*;

public class GraphicsPolygon {

/**

* The main method.

* @param args Command line argument list

*/

public static void main( String args[] )

{

// Initialize graphics context

PolygonFrame gui = new PolygonFrame();

Graphics easel = gui.getGraphics();

final int stretch = 5;

// Initialize Text object in to read from standard input.

TokenReader in = new TokenReader( System.in );

// Starting coordinates for current polygon

int firstX, firstY;

// Coordinates of xMin, yMin, xMax, and yMax for current polygon

int xMin, yMin, xMax, yMax;

// Coordinates of latest point entered

int x, y;

System.out.println( "Enter the coordinates: " );

xMin = xMax = firstX = x = in.readInt();

yMin = yMax = firstY = y = in.readInt();

// Continue to draw lines and polygons until the user enters negative values

while ( x >=0 && y >=0 )

{

int xPrev = x;

int yPrev = y;

x = in.readInt();

y = in.readInt();

// Update minimum and maximum variables if necessary

if ( x < xMin )

xMin = x;

else if ( x > xMax )

xMax = x;

if ( y < yMin )

yMin = y;

else if (y > yMax )

yMax = y;

// Draw a line to the current point only if the current point is not -1 -1

if ( x != -1 && y != -1 )

GraphicsUtil.drawLine(easel, (stretch * xPrev), (stretch * yPrev),

(stretch * x), (stretch * y), 4, Color.blue);

// Draw bounding rectangle if we have a closed polygon

if ( x == firstX && y == firstY )

{

GraphicsUtil.drawRect(easel, (stretch * xMin ), (stretch * yMin ),

( stretch *( xMax-xMin )), (stretch *( yMax-yMin )), 3, Color.green);

xMin = xMax = firstX = x = in.readInt();

yMin = yMax = firstY = y = in.readInt();

}

} // end while

}

}

Alternate solution template ( using nested do-while loops )

System.out.println( "Enter the coordinates: " );

do {

xMax = xMin = x = xFirst = in.readInt();

yMax = yMin = y = yFirst = in.readInt();

do{

// Update minimum and maximum variables if necessary

if ( x < xMin )

xMin = x;

else if ( x > xMax )

xMax = x;

if ( y < yMin )

yMin = y;

else if (y > yMax )

yMax = y;

int xPrev = x;

int yPrev = y;

x = in.readInt();

y = in.readInt();

// Draw a line to the current point only if the current point is not -1 -1

if ( x != -1 && y != -1 )

GraphicsUtil.drawLine(easel, ( stretch * xPrev ), ( stretch * yPrev ),

( stretch * x ), ( stretch * y ), 4, Color.blue);

} while ( x != xFirst || y != yFirst );

// Draw bounding box

GraphicsUtil.drawRect(easel, ( stretch * xMin ), ( stretch * yMin ),

(stretch *( xMax - xMin )), (stretch *( yMax - yMin )), 3, Color.green);

} while ( x>=0 && y>=0 );