I keep getting a java.lang.NullPointerException when adding points
The lines from this i have put in italics
I have a shop, and i need to add points to buy an item.
This is the code i use to access the points from different actors, this is in MyWorld
This is the code that i use to Display the points and change the points
This is the code that should deduct from the points, this is in an actor called PurchaseI1
Please help, this is for a school assignment and i would like to get the shop working so i can add it to my game
java.lang.NullPointerException at Points.changeCounter(Points.java:23) at PurchaseI1.purchase(PurchaseI1.java:31) at PurchaseI1.act(PurchaseI1.java:22) at greenfoot.core.Simulation.actActor(Simulation.java:594) at greenfoot.core.Simulation.runOneLoop(Simulation.java:552) at greenfoot.core.Simulation.runContent(Simulation.java:215) at greenfoot.core.Simulation.run(Simulation.java:205)
public int counter = 0;
Points points = new Points();
private int time = 3600;
public Points getPoints()
{
return points;
} public void act()
{
setImage(new GreenfootImage("Points: " + ((MyWorld)getWorld()).counter, 24, Color.BLACK, new Color(0, 0, 0, 0)));
}
public void changeCounter(int amount)
{
[i]((MyWorld)getWorld()).counter = ((MyWorld)getWorld()).counter + amount;[/i]
}
public void act()
{
[i]purchase();[/i]
}
public void purchase()
{
if(((MyWorld)getWorld()).counter >= 2 )
{
MyWorld world = (MyWorld)getWorld();
Points points = world.getPoints();
[i] points.changeCounter(-2);[/i]
}
}