Yoshi21137 wrote...
and it won't construct the world until whatever is wrong is fixed
tried the first option but it says there is also something wrong with:
<< Code Omitted >>
Yoshi21137 wrote ...
2020/2/25
int in showText
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Knight:
import greenfoot.*; // (World, Actor, GreenfootImage, Greenfoot and MouseInfo)
/**
* Write a description of class Knight here.
*
* @author (your name)
* @version (a version number or a date)
*/
public class Knight extends Players
{
Main main = (Main)getWorld();
int kills = main.kills;
int bulletSpeed = 100;
int lives = ((Main)getWorld()).lives;
/**
* Act - do whatever the Knight wants to do. This method is called whenever
* the 'Act' or 'Run' button gets pressed in the environment.
*/
public void act()
{
checkKeys();
looseHealth();
}
public void looseHealth()
{
if (canSee(GoblinShaman.class))
{
lives = lives-1;
}
}
public void checkKeys()
{
if (Greenfoot.isKeyDown("w"))
{
turn(-90);
move(5);
turn(90);
}
if (Greenfoot.isKeyDown("s"))
{
turn(90);
move(5);
turn(-90);
}
if (Greenfoot.isKeyDown("d"))
{
move(5);
}
if (Greenfoot.isKeyDown("a"))
{
move(-5);
}
if(Greenfoot.isKeyDown("enter") && getObjectsInRange(bulletSpeed, Bullet.class).isEmpty())
{
getWorld().addObject(new Bullet(), getX()+40, getY()+8);
}
}
}You cannot dot getWorld in a field declaration line (line 14). It is executed during object (actor, in this case) creation and will return a null value since the actor cannot be in a world while being created. Doing anything to a null value will result in a NullPointerException error.
Honestly, it is not wise to have two different classes hold the same value in fields of primitive type (int, double, boolean, long, etc.). Keep its value with the object that it describes and have it accessed when needed by other objects.
Now it is showing there is a problem in here
public void die()
{
if (canSee(Bullet.class))
{
(main).kills = (main).kills+1
main.removeObject(this)
}
}I forgot to type the semicolon at the end of line 7 when posting
I tried using that but it is saying there is a problem
public void die()
{
if (canSee(Bullet.class))
{
(main).kills = (main).kills+1;
main.removeObject(this);
}
}(main).kills = (main).kills+1;
Main main = (main)getWorld();
public void die()
{
if (canSee(Bullet.class))
{
(main).kills = (main).kills+1;
main.removeObject(this);
}
}You cannot expect the actor (who dies from being hit by a bullet) to be in a world while being created. Your main field will be set to null as it is assigned the value of (main)getWorld() while it is being created. Move line 1 to inside the if clause.
I used that and moved it to the bullet class and it works but the counter doesn't
this is the current code:
public void kill()
{
if (isTouching(GoblinShaman.class))
{
Main main = (Main)getWorld();
removeTouching(GoblinShaman.class);
main.kills = main.kills+1;
}
} int kills = 0;
/**
* Constructor for objects of class MyWorld.
*
*/
public Main()
{
super(1000, 650, 1);
prepare();
showText(""+lives, 73, 42);
showText(""+kills, 73, 66);
}Maybe you should change line 7 so that, instead of just changing the value of kills, you call a method in Main that changes its value AND updates the display.
How would I do that?
It works now. Thanks for helping me and for staying with me for the 3 days you did!
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