Working on a tortoise and hare project. This method should draw the the tortoises and hares but I'm getting an error message.
protected void paintComponent( Graphics g )
{
super.paintComponent( g );
// draw the finish line
finishX = getWidth( ) - 20;
g.setColor( Color.blue );
g.drawLine( finishX, 0, finishX, getHeight( ) );
if ( raceIsOn )
{
/* loop through instance variable ArrayList racerList,
* which contains Racer object references,
* calling draw and move for each element.
*/
for (int i = 0; i < racerList.size(); i++)
{
move();
draw (Graphics g);
}
}
else // display racers before race begins
{
/* loop through instance variable ArrayList racerList,
* which contains Racer object references,
* calling draw for each element.
*/
for (int i = 0; i < racerList.size(); i++)
{
draw();
}
}
}
Here is part of the class i am trying to call
/** abstract method for Racer's move
*/
public abstract void move( );
/** abstract method for drawing Racer
* @param g Graphics context
*/
public abstract void draw( Graphics g );
Here is the entire class
import java.awt.*;
import javax.swing.*;
import java.util.ArrayList;
public class RacePoly extends JFrame
{
private ArrayList<Racer> racerList; // racers stored in ArrayList
private static RacePoly app;
private final int FIRST_RACER = 50;
private int finishX; // location of finish line, dependent on window width
private boolean raceIsOn = false;
private RacePanel racePanel;
/** Constructor
* instantiates list to track racers
* sets up GUI components
*/
public RacePoly( )
{
super( "The Tortoise & The Hare!" );
Container c = getContentPane( );
racePanel = new RacePanel( );
c.add( racePanel, BorderLayout.CENTER );
racerList = new ArrayList<Racer>( );
setSize( 400, 400 );
setVisible( true );
}
/** prepareToRace method
* uses a dialog box to prompt user for racer types
* and to start the race
* racer types are 't' or 'T' for Tortoise,
* 'h' or 'H' for Hare
* 's' or 'S' will start the race
*/
private void prepareToRace( )
{
int yPos = FIRST_RACER; // y position of first racer
final int START_LINE = 40; // x position of start of race
final int RACER_SPACE = 50; // spacing between racers
char input;
input = getRacer( ); // get input from user
while ( input != 's' && input != 'S' )
{
switch (input)
{
case 'T':
case 't':
racerList.add(new Tortoise( "Tortoise", START_LINE, yPos ));
yPos+=RACER_SPACE;
break;
case 'H':
case 'h':
racerList.add(new Hare( "Hare", START_LINE, yPos ));
yPos+=RACER_SPACE;
break;
default:
JOptionPane.showMessageDialog( this, "That was not a T or H you bitch." );
break;
}
* If input is 'H' or 'h',
* add a Hare object to the ArrayList named racerList
* The API of the Hare constructor is:
* Hare( String ID, int startX, int startY )
* a sample call to the constructor is
* new Hare( "Hare", START_LINE, yPos )
* where START_LINE is a constant local variable
* representing the starting x position for the race
* and yPos is a local variable representing
* the next racer's y position
*
* After adding a racer to the ArrayList racerList,
* increment yPos by the value of
* the constant local variable RACER_SPACE
*
* if input is anything other than 'T', 't',
* 'H' or 'h', pop up an error dialog box
* a sample method call for the output dialog box is:
* JOptionPane.showMessageDialog( this, "Message" );
*/
repaint( );
input = getRacer( ); // get input from user
} // end while
}
private class RacePanel extends JPanel
{
/** paint method
* @param g Graphics context
* draws the finish line;
* moves and draws racers
*/
protected void paintComponent( Graphics g )
{
super.paintComponent( g );
// draw the finish line
finishX = getWidth( ) - 20;
g.setColor( Color.blue );
g.drawLine( finishX, 0, finishX, getHeight( ) );
if ( raceIsOn )
{
/* loop through instance variable ArrayList racerList,
* which contains Racer object references,
* calling draw and move for each element.
*/
for (int i = 0; i < racerList.size(); i++)
{
move();
draw (g);
}
}
else // display racers before race begins
{
/* loop through instance variable ArrayList racerList,
* which contains Racer object references,
* calling draw for each element.
*/
for (int i = 0; i < racerList.size(); i++)
{
draw();
}
}
}
}
/** runRace method
* checks whether any racers have been added to racerList
* if no racers, exits with message
* otherwise, runs race, calls repaint to move & draw racers
* calls reportRaceResults to identify winners(s)
* calls reset to set up for next race
*/
public void runRace( )
{
if ( racerList.size( ) == 0 )
{
JOptionPane.showMessageDialog( this,
"The race has no racers. exiting",
"No Racers", JOptionPane.ERROR_MESSAGE );
System.exit( 0 );
}
raceIsOn = true;
while ( ! findWinner( ) )
{
Pause.wait(.03);
repaint( );
} // end while
reportRaceResults( );
reset( );
}
/** gets racer selection from user
* @return first character of user entry
* if user presses cancel, exits the program
*/
private char getRacer( )
{
String input = JOptionPane.showInputDialog( this, "Enter a racer:"
+ "\nt for Tortoise, h for hare,"
+ "\nor s to start the race" );
if ( input == null )
{
System.out.println( "Exiting" );
System.exit( 0 );
}
if ( input.length( ) == 0 )
return 'n';
else
return input.charAt( 0 );
}
/** findWinners:
* checks for any racer whose x position is past the finish line
* @return true if any racer's x position is past the finish line
* or false if no racer's x position is past the finish line
*/
private boolean findWinner( )
{
for ( Racer r : racerList )
{
if ( r.getX( ) > finishX )
return true;
}
return false;
}
/** reportRaceResults : compiles winner names and prints message
* winners are all racers whose x position is past the finish line
*/
private void reportRaceResults( )
{
raceIsOn = false;
String results = "Racer ";
for ( int i = 0; i < racerList.size( ); i ++ )
{
if ( racerList.get( i ).getX( ) > finishX )
{
results += ( i + 1 ) + ", a " + racerList.get( i ).getID( ) + ", ";
}
}
JOptionPane.showMessageDialog( this, results + " win(s) the race " );
}
/** reset: sets up for next race:
* sets raceIsOn flag to false
* clears the list of racers
* resets racer position to FIRST_RACER
* enables checkboxes and radio buttons
*/
private void reset( )
{
char answer;
String input = JOptionPane.showInputDialog( this, "Another race? (y, n)" );
if ( input == null || input.length( ) == 0 )
{
System.out.println( "Exiting" );
System.exit( 0 );
}
answer = input.charAt( 0 );
if ( answer == 'y' || answer == 'Y' )
{
raceIsOn = false;
racerList.clear( );
app.prepareToRace( );
app.runRace( );
}
else
System.exit( 0 );
}
/** main
* instantiates the RacePoly object app
* calls runRace method
*/
public static void main( String [] args )
{
app = new RacePoly( );
app.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
app.prepareToRace( );
app.runRace( );
}
}
Racer class
import java.awt.Graphics;
public abstract class Racer
{
private String ID; // racer ID
private int x; // x position
private int y; // y position
/** default constructor
* Sets ID to blank
*/
public Racer( )
{
ID = "";
}
/** Constructor
* @param rID racer ID
* @param rX x position
* @param rY y position
*/
public Racer( String rID, int rX, int rY )
{
ID = rID;
x = rX;
y = rY;
}
/** accessor for ID
* @return ID
*/
public String getID( )
{
return ID;
}
/** accessor for x
* @return current x value
*/
public int getX( )
{
return x;
}
/** accessor for y
* @return current y value
*/
public int getY( )
{
return y;
}
/** mutator for x
* @param newX new value for x
*/
public void setX( int newX )
{
x = newX;
}
/** mutator for y
* @param newY new value for y
*/
public void setY( int newY )
{
y = newY;
}
/** abstract method for Racer's move
*/
public abstract void move( );
/** abstract method for drawing Racer
* @param g Graphics context
*/
public abstract void draw( Graphics g );
}
Tortoise Class
/** Tortoise class
* inherits from abstract Racer class
*/
import java.awt.Graphics;
import java.awt.Color;
import java.util.Random;
public class Tortoise extends Racer
{
private int speed;
private Random rand;
/** Default Constructor: calls Racer default constructor
*/
public Tortoise( )
{
super( );
// percentage of time (between 90 - 99%) that this tortoise moves each turn
rand = new Random( );
speed = rand.nextInt( 10 ) + 90;
}
/** Constructor
* @param rID racer Id, passed to Racer constructor
* @param rX x position, passed to Racer constructor
* @param rY y position, passed to Racer constructor
*/
public Tortoise( String rID, int rX, int rY )
{
super( rID, rX, rY );
// percentage of time (between 90 - 99%) that this tortoise moves each turn
rand = new Random( );
speed = rand.nextInt( 10 ) + 90;
}
/** move: calculates the new x position for the racer
* Tortoise move characteristics: "slow & steady wins the race"
* increment x by 1 most of the time
*/
public void move( )
{
int move = rand.nextInt( 100 ) + 1;
if ( move < speed )
setX( getX( ) + 1 );
}
/** draw: draws the Tortoise at current (x, y) coordinate
* @param g Graphics context
*/
public void draw( Graphics g )
{
int startX = getX( );
int startY = getY( );
g.setColor( new Color( 34, 139, 34 ) ); // dark green
//body
g.fillOval( startX - 30, startY, 25, 15 );
//head
g.fillOval( startX - 10, startY + 5, 15, 10 );
//flatten bottom
g.clearRect( startX - 30, startY + 11, 35, 4 );
//feet
g.setColor( new Color( 34, 139, 34 ) ); // brown
g.fillOval( startX - 27, startY + 10, 5, 5 );
g.fillOval( startX - 13, startY + 10, 5, 5 );
}
}
Hare Class
/** Hare class
* inherits from abstract Racer class
*/
import java.awt.Graphics;
import java.awt.Color;
import java.util.Random;
public class Hare extends Racer
{
/** Default Constructor: calls Racer default constructor
*/
public Hare( )
{
super( );
}
/** Constructor
* @param rID racer Id, passed to Racer constructor
* @param rX x position, passed to Racer constructor
* @param rY y position, passed to Racer constructor
*/
public Hare( String rID, int rX, int rY )
{
super( rID, rX, rY );
}
/** move: calculates the new x position for the racer
* Hare move characteristics: 30% of the time, Hare jumps 5 pixels
* 70% of the time, Hare sleeps (no move)
* generates random number between 1 & 10
* for 1 - 7, no change to x position
* for 8 - 10, x position is incremented by 5
*/
public void move( )
{
Random rand = new Random( );
int move = rand.nextInt( 10 ) + 1 ;
if ( getX( ) < 100 )
{
if ( move > 6 )
setX( getX( ) + 4 );
}
else
{
if ( move > 8 )
setX( getX( ) + 4 );
}
}
/** draw: draws the Hare at current (x, y) coordinate
* @param g Graphics context
*/
public void draw( Graphics g )
{
int startY = getY( );
int startX = getX( );
// tail
g.setColor( Color.LIGHT_GRAY );
g.fillOval( startX - 37, startY + 8, 12, 12 ) ;
//body
g.setColor( Color.GRAY );
g.fillOval( startX - 30, startY, 20, 20 );
//head
g.fillOval( startX - 13, startY + 2, 13, 8 );
g.fillOval( startX - 13, startY - 8, 8, 28 );
//flatten bottom
g.clearRect( startX - 37, startY + 15, 32, 5 );
}
}
https://stackoverflow.com/questions/22370032
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