No idea why my code won't work...

[hopelessnoob]

I'm writing a simple boxing match code, which compiles fine, but when I run it only one of the two boxers appears (in the middle of the ring), the keystroke for the right boxer to move right makes another boxer appear on the left, the punch and move left keystrokes for the right boxer do nothing, the punch and move right keystrokes for the left boxer do nothing and the move left keystroke for the left boxer (after he has appeared) doesn't erase the old position boxer (even though I repaint the background each time). My Boxer.java code is:

public class Boxer {

//variables

private int health=100;
private int position;
private boolean punching=false;
private static int ringwidth;
static int boxers;
private int boxerno;

//constructors

public Boxer(){
if (boxers==0){
position=(int)(-ringwidth/2);
boxers=1;
boxerno=1;
} else if(boxers==1) {
position=(int)(ringwidth/2);
boxers=2;
boxerno=2;
}
}

//getters and setters

public static void setRingwidth(int x){
ringwidth=x;
}

public static int getRingwidth(){
return ringwidth;
}

public void setHealth(int x) {
if(x<101){
health=x;
} else {
health=100;
}
}

public int getHealth() {
return health;
}

public void setPosition(int x){
if(2*x>ringwidth){
position=(int)(ringwidth/2);
} else if(-2*x<ringwidth){
position=(int)(-ringwidth/2);
} else {
position=x;
}
}

public int getPosition(){
return position;
}

public void setPunching(boolean b) {
punching=b;
}

public boolean getPunching(){
return punching;
}

public int getBoxerno(){
return boxerno;
}

//methods

public void punched(int[] powerposition){
if(position-powerposition[1]<11&&position-powerposition[1]>-11){
setHealth(getHealth()-powerposition[0]);
}
}

public int[] punch(){
setPunching(true);
int x=(int) (25+getHealth()/2);
int[] powerposition=new int[2];
powerposition[0]=x;
powerposition[1]=position;
setPunching(false);
return powerposition;
}

public void moveleft(){
setPosition(getPosition()-10);
}

public void moveright(){
setPosition(getPosition()+10);
}
}

and the boxingmatch.java code is:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.color.*;

public class boxingmatch implements KeyListener{
public static void main (String[] args) {
boxingmatch box=new boxingmatch();
box.go();
}

Boxer a;
Boxer b;
Picture pic;

public void go(){
JFrame frame=new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JTextField tfield=new JTextField();
a=new Boxer();
b=new Boxer();
pic=new Picture();
pic.repaint();
frame.getContentPane().add(BorderLayout.SOUTH,tfield);
frame.getContentPane().add(BorderLayout.CENTER,pic);
frame.setSize(900,900);
frame.setVisible(true);
Boxer.setRingwidth(pic.getWidth()*10/11);
tfield.setFocusable(true);
tfield.addKeyListener(this);
tfield.requestFocus();
}

public void keyTyped(KeyEvent event) {
}

public void keyReleased(KeyEvent event) {
}

public void keyPressed(KeyEvent event) {
if(event.getKeyCode()==KeyEvent.VK_A) {
a.moveleft();
} else if(event.getKeyCode()==KeyEvent.VK_D) {
a.moveright();
} else if(event.getKeyCode()==KeyEvent.VK_S) {
b.punched(a.punch());
} else if(event.getKeyCode()==KeyEvent.VK_K) {
a.punched(b.punch());
} else if(event.getKeyCode()==KeyEvent.VK_L) {
b.moveright();
} else if(event.getKeyCode()==KeyEvent.VK_J) {
b.moveright();
}
pic.repaint();
}

class Picture extends JPanel {
public void paintComponent (Graphics g) {
g.setColor(Color.black);
g.fillRect(0,0,this.getWidth(),this.getHeight());
g.setColor(Color.red);
g.fillRect(0,(int)(this.getHeight()*49/100),this.getWidth(),(int)(this.getHeight()*1/50));
g.fillRect(0,(int)(this.getHeight()*59/100),this.getWidth(),(int)(this.getHeight()*1/50));
g.fillRect(0,(int)(this.getHeight()*69/100),this.getWidth(),(int)(this.getHeight()*1/50));
g.setColor(Color.blue);
g.fillRect(0,(int)(this.getHeight()*4/5),this.getWidth(),(int)(this.getHeight()*1/5));
Color skin=new Color(239,238,207);
g.setColor(skin);
g.fillRect((int)(this.getWidth()/2+a.getPosition()-this.getWidth()/20),(int)(this.getHeight()/10),(int)(this.getWidth()/10),(int)(this.getHeight()*9/10));
g.fillRect((int)(this.getWidth()/2+b.getPosition()-this.getWidth()/20),(int)(this.getHeight()/10),(int)(this.getWidth()/10),(int)(this.getHeight()*9/10));
g.setColor(Color.black);
g.fillRect((int)(this.getWidth()/2+a.getPosition()-this.getWidth()/20),(int)(this.getHeight()/10),(int)(this.getWidth()/10),(int)(this.getHeight()*1/20));
g.fillRect((int)(this.getWidth()/2+b.getPosition()-this.getWidth()/20),(int)(this.getHeight()/10),(int)(this.getWidth()/10),(int)(this.getHeight()*1/20));
g.fillRect((int)(this.getWidth()/2+a.getPosition()-1),(int)(this.getHeight()*3/4),2,(int)(this.getHeight()*1/4));
g.fillRect((int)(this.getWidth()/2+b.getPosition()-1),(int)(this.getHeight()*3/4),2,(int)(this.getHeight()*1/4));
g.setColor(Color.green);
g.fillRect((int)(this.getWidth()/2+a.getPosition()-this.getWidth()/20),(int)(this.getHeight()*11/20),(int)(this.getWidth()/10),(int)(this.getHeight()*1/5));
g.fillRect((int)(this.getWidth()/2+b.getPosition()-this.getWidth()/20),(int)(this.getHeight()*11/20),(int)(this.getWidth()/10),(int)(this.getHeight()*1/5));
g.setColor(skin);
if (a.getPunching()) {
g.fillRect((int)(this.getWidth()/2+a.getPosition()),(int)(this.getHeight()*1/4),(int)(this.getWidth()*3/10),(int)(this.getHeight()*1/15));
}
if (b.getPunching()) {
g.fillRect((int)(this.getWidth()/2+b.getPosition()),(int)(this.getHeight()*1/4),-(int)(this.getWidth()*3/10),-(int)(this.getHeight()*1/15));
}
}
}
}

sorry for so much code, but as it thinks it's a healthy program I can't find where the errors are coming from.

[Fubarable]

Could you post formatted code so we are able to read it? Also, how is it not working? Errors? Exceptions? Incorrect behavior? Details and any and all error messages will help us.

[hopelessnoob]

I wrapped the code above in [c ode] [/c ode] but I can't work out how to show line numbers along the side...

There are no errors or exceptions whatsoever, it thinks it's a healthy code, and I can't find where the mistakes come from when I read the code :(

[Fubarable]

I wrapped the code above in [c ode] [/c ode] but I can't work out how to show line numbers along the side...

Heck, I don't want line numbers, but is all of your code without any indentations whatsoever and fully left justified? I don't know about you, but I find non-indented code very difficult if not impossible to read. And my experience here has been that the easier you make it for someone else to understand your problem and answer it, the better your chances of getting a decent answer. But up to you.

[hopelessnoob]

I'm sorry, I've never considered indentations (I write my code in notepad and run with command prompt).
Does the compiler ignore tabs as it does spaces?
Here is my indented code (one indentation in or out as appropriate at each { or }, is that the etiquette?)
boxingmatch.java:

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.color.*;

public class boxingmatch implements KeyListener{
	public static void main (String[] args) {
		boxingmatch box=new boxingmatch();
		box.go();
	}

	Boxer a;
	Boxer b;
	Picture pic;

	public void go(){
		JFrame frame=new JFrame();
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		JTextField tfield=new JTextField();
		a=new Boxer();
		b=new Boxer();
		pic=new Picture();
		pic.repaint();
		frame.getContentPane().add(BorderLayout.SOUTH,tfield);
		frame.getContentPane().add(BorderLayout.CENTER,pic);
		frame.setSize(900,900);
		frame.setVisible(true);
		Boxer.setRingwidth(pic.getWidth()*10/11);
		tfield.setFocusable(true);
		tfield.addKeyListener(this);
		tfield.requestFocus();
	}

	public void keyTyped(KeyEvent event) {
	}

	public void keyReleased(KeyEvent event) {
	}

	public void keyPressed(KeyEvent event) {
		if(event.getKeyCode()==KeyEvent.VK_A) {
			a.moveleft();
		} else if(event.getKeyCode()==KeyEvent.VK_D) {
			a.moveright();
		} else if(event.getKeyCode()==KeyEvent.VK_S) {
			b.punched(a.punch());
		} else if(event.getKeyCode()==KeyEvent.VK_K) {
			a.punched(b.punch());
		} else if(event.getKeyCode()==KeyEvent.VK_L) {
			b.moveright();
		} else if(event.getKeyCode()==KeyEvent.VK_J) {
			b.moveright();
		}
		pic.repaint();
	}

class Picture extends JPanel {
	public void paintComponent (Graphics g) {
		g.setColor(Color.black);
		g.fillRect(0,0,this.getWidth(),this.getHeight());
		g.setColor(Color.red);
		g.fillRect(0,(int)(this.getHeight()*49/100),this.getWidth(),(int)(this.getHeight()*1/50));
		g.fillRect(0,(int)(this.getHeight()*59/100),this.getWidth(),(int)(this.getHeight()*1/50));
		g.fillRect(0,(int)(this.getHeight()*69/100),this.getWidth(),(int)(this.getHeight()*1/50));
		g.setColor(Color.blue);
		g.fillRect(0,(int)(this.getHeight()*4/5),this.getWidth(),(int)(this.getHeight()*1/5));
		Color skin=new Color(239,238,207);
		g.setColor(skin);
		g.fillRect((int)(this.getWidth()/2+a.getPosition()-this.getWidth()/20),(int)(this.getHeight()/10),(int)(this.getWidth()/10),(int)

(this.getHeight()*9/10));
		g.fillRect((int)(this.getWidth()/2+b.getPosition()-this.getWidth()/20),(int)(this.getHeight()/10),(int)(this.getWidth()/10),(int)

(this.getHeight()*9/10));
		g.setColor(Color.black);
		g.fillRect((int)(this.getWidth()/2+a.getPosition()-this.getWidth()/20),(int)(this.getHeight()/10),(int)(this.getWidth()/10),(int)

(this.getHeight()*1/20));
		g.fillRect((int)(this.getWidth()/2+b.getPosition()-this.getWidth()/20),(int)(this.getHeight()/10),(int)(this.getWidth()/10),(int)

(this.getHeight()*1/20));
		g.fillRect((int)(this.getWidth()/2+a.getPosition()-1),(int)(this.getHeight()*3/4),2,(int)(this.getHeight()*1/4));
		g.fillRect((int)(this.getWidth()/2+b.getPosition()-1),(int)(this.getHeight()*3/4),2,(int)(this.getHeight()*1/4));
		g.setColor(Color.green);
		g.fillRect((int)(this.getWidth()/2+a.getPosition()-this.getWidth()/20),(int)(this.getHeight()*11/20),(int)(this.getWidth()/10),(int)		

(this.getHeight()*1/5));
		g.fillRect((int)(this.getWidth()/2+b.getPosition()-this.getWidth()/20),(int)(this.getHeight()*11/20),(int)(this.getWidth()/10),(int)

(this.getHeight()*1/5));
		g.setColor(skin);
		if (a.getPunching()) {
			g.fillRect((int)(this.getWidth()/2+a.getPosition()),(int)(this.getHeight()*1/4),(int)(this.getWidth()*3/10),(int)(this.getHeight()

*1/15));
		}
		if (b.getPunching()) {
			g.fillRect((int)(this.getWidth()/2+b.getPosition()),(int)(this.getHeight()*1/4),-(int)(this.getWidth()*3/10),-(int)(this.getHeight()

*1/15));
		}
	}
}
}

Boxer.java:

public class Boxer {

//variables

	private int health=100;
	private int position;
	private boolean punching=false;
	private static int ringwidth;
	static int boxers;
	private int boxerno;

//constructors

	public Boxer(){
		if (boxers==0){
			position=(int)(-ringwidth/2);
			boxers=1;
			boxerno=1;
		} else if(boxers==1) {
			position=(int)(ringwidth/2);
			boxers=2;
			boxerno=2;
		}
	}

//getters and setters

	public static void setRingwidth(int x){
		ringwidth=x;
	}

	public static int getRingwidth(){
		return ringwidth;
	}

	public void setHealth(int x) {
		if(x<101){
			health=x;
		} else {
			health=100;
		}
	}

	public int getHealth() {
		return health;
	}

	public void setPosition(int x){
		if(2*x>ringwidth){
			position=(int)(ringwidth/2);
		} else if(-2*x<ringwidth){
			position=(int)(-ringwidth/2);
		} else {
			position=x;
		}
	}

	public int getPosition(){
		return position;
	}

	public void setPunching(boolean b) {
		punching=b;
	}

	public boolean getPunching(){
		return punching;
	}

	public int getBoxerno(){
		return boxerno;
	}

//methods

	public void punched(int[] powerposition){
		if(position-powerposition[1]<11&&position-powerposition[1]>-11){
			setHealth(getHealth()-powerposition[0]);
		}
	}

	public int[] punch(){
		setPunching(true);
		int x=(int) (25+getHealth()/2);
		int[] powerposition=new int[2];
		powerposition[0]=x;
		powerposition[1]=position;
		setPunching(false);
		return powerposition;
	}

	public void moveleft(){
		setPosition(getPosition()-10);
	}

	public void moveright(){
		setPosition(getPosition()+10);
	}
}

As I say, neither the compiler nor the jvm have any problem with my code, it just doesn't do what it's meant to.

[ozzyman]

rather than throw 5 problems at us you should've taken it one method at a time. anyhow, let's try to break-down your program-logic.

when I run it only one of the two boxers appears (in the middle of the ring)

your program follows this path when run...

BoxingMatch.go()
...
a = new Boxer()
b = new Boxer()
	public Boxer(){
		if (boxers==0){
			position=(int)(-ringwidth/2);
			boxers=1;
			boxerno=1;
		} else if(boxers==1) {
			position=(int)(ringwidth/2);
			boxers=2;
			boxerno=2;
		}
	}

firstly, i'm surprised that any boxer shows up since the variable 'boxers' was not initialised:

static int boxers;

which means that boxers should = 'null' rather than '0' to start off with. secondly, the second boxer will never show up unless the first boxer has been created, because 'if boxers==1' doesn't happen in your script except when the first boxer is made. i understand that you wanted to limit the number of boxers created to two, but there are better ways to do this, e.g.

public Boxer() {
  if (boxers == 0) {
    //set position for boxer 1
  } else if (boxers == 1) {
    //set position for boxer 2
  }
  boxerno = ++boxers; //the boxerno = boxers+1 & boxers = boxers+1
}

as for the boxers spawning in the middle, this is easily explainable by your calculation of setting the position of the boxers. you've set boxer 1's position to:

position=(int)(-ringwidth/2);

say the ring is 300 pixels wide. 300/2 = 150 pixels. that would be the middle of the ring. however, for boxer 1 you have used negative-ringwidth. which means that the boxer1s position is set outside of the viewable area of your applet which would be 0 to 300 pixels (i.e. -150 horizontal is not shown on your screen).

as for the next boxer,

position=(int)(ringwidth/2);

positive-ringwidth/2 = middle of the ring. change this to something like:

position = (int) (ringwidth - 20 - WIDTH_OF_BOXER);

to make boxer2 start 20pixels from the right-border of the ring. similarly you could set boxer1 to:

position = 20;

which would set it 20pixels from the left border of the ring.

[ozzyman]

the keystroke for the right boxer to move right makes another boxer appear on the left

i'm guessing this "new" boxer is actually the boxer1 whose initial position was set to -150px (i.e. hidden)

[Junky]

which means that boxers should = 'null' rather than '0' to start off with.

No. Primitives can never by null. Uninitialised variables are given their default values. For int/long etc it is 0. For double/float it is 0.0. For boolean it is false. For char it is a space. Reference variables (objects) it is null.

[ozzyman]

the punch and move left keystrokes for the right boxer do nothing, the punch and move right keystrokes for the left boxer do nothing and the move left keystroke for the left boxer (after he has appeared) doesn't erase the old position boxer (even though I repaint the background each time).

if i want to move the position to the right, and x=20, setPosition is called and this is what happens...

if (2*20 > 300) { //does not become true unless x is between 150-300pixels - why?
  position=(int)(ringwidth/2); //set position to middle of the ring
} else if (-2*20 < 300) { //if the boxer is off the screen - why? - as with boxer1 (-150 in your case) {
  position=(int)(-ringwidth/2); //set position off-screen
} else {
  position = x; //set to the position it is supposed to be set to
}

...which means that if the any boxer is between (150 to 300) or (0 to -infinity) the boxers position is not set. i think what you mean to write is something to the tune of this pseudo-code:

if (boxer1.position is between 0 and half way) {
  //set new position
} else if (boxer1.position is < 0) {
  //set boxer1.position to 0
} else if (boxer1.position > half-way) {
  //set boxer1.position to half-way
}

for boxer1-only and something else but similar for boxer2

[ozzyman]

No. Primitives can never by null. Uninitialised variables are given their default values. For int/long etc it is 0. For double/float it is 0.0. For boolean it is false. For char it is a space. Reference variables (objects) it is null.

Thanks for that Junky, I never knew.

[DarrylBurke]

For char it is a space.

No, it isn't. It's (char) 0, also known as the nul character (note: nul, not null).

public class DefaultCharValue {

  private char c;

  public static void main(String[] args) {
    DefaultCharValue dfv = new DefaultCharValue();
    System.out.println("Default value of c is [" + dfv.c + "] (numeric value = " + (int) dfv.c + ")");
    dfv.c = ' ';
    System.out.println("Value of c is now [" + dfv.c + "] (numeric value = " + (int) dfv.c + ")");
  }
}

[Junky]

Ahh my bad. When I tested printing out the default value it looks like there is a space. But I guess the default value for char is unprintable.