Greenfoot

kiarocks

2011/6/11

#

I'm making a game that has a percent chance to change the image of an actor if it is next to a certain actor. How do I do this?

danpost

2011/6/11

#

You could use the 'Greenfoot.getRandomNumber(int)' . If you wanted 20 percent chance, the code would look like this:

if (Greenfoot.getRandomNumber(100) <  20)
{
    // change the image here
}

For any other percentage, just change the 20 to the percentage you want.

kiarocks

2011/6/11

#

ok thanks!

kiarocks

2011/6/11

#

but im having another problem. here is the code

  public boolean infect;
    {
        
    World theWorld = getWorld(); 
    if (Greenfoot.getRandomNumber(100) <  25)  
{  
    setImage("ppl2.gif");
}  
        List Uninfect = getObjectsInRange(2, InfectLv1.class);
    if(Uninfect.isEmpty()) 
         
             return false;
            
        
        else {
            return true;
        }

and it says return outside method. How do i fix this. Im new so Im trying to figure out as much as possible.

davmac

2011/6/11

#

First thing: if you get the indentation right, it makes the code structure much easier to see and understand. Use the "auto-layout" function from the edit menu! Now, the problem with this code is actually the ";" that you have immediately after "infect". You want to declare a method, so the format is: public boolean infect { .... As it is, the compiler sees "public boolean infect;" and thinks you are trying to declare a variable called "infect" rather than a method called "infect". Just remove the ";" !!

kiarocks

2011/6/11

#

says";" expected now, though

danpost

2011/6/11

#

Put '()' at the end of your method declaration as such

    public boolean infect()
    {
        // code here
    }

Also, your original error message 'return outside method' is because you are missing brackets around the return statement after the 'if' clause. This should be as such:

    if (Uninfect.isEmpty())
    {
        return false;
    }
    else
    {
        return true;
    }

Now better, and more convenient, would be this:

    return !Uninfect.isEmpty();

It take the boolean value (Uninfect.isEmpty()), "nots" it (!), and then returns it. I did not try it, but you may have to write it this way:

    return !(Uninfect.isEmpty());

I am fairly new at java myself, but I am familiar with programming languages (syntax can be a bear).

danpost

2011/6/11

#

Try this -- let me know if it works.

 return ((getObjectsInRange(2,InfectLv1.class)).size() != 0);

kiarocks

2011/6/11

#

still same message as before-where should i put the code?

danpost

2011/6/11

#

I'll need to see your code and know what error message you got. And where did YOU put the code?

kiarocks

2011/6/11

#

now it works! Thanks!!

danpost

2011/6/11

#

Glad to hear it! Did you try the one-liner return statement?

kiarocks

2011/6/11

#

public boolean infect()
    {

        World theWorld = getWorld(); 

        if (Greenfoot.getRandomNumber(100) <  100) <set for 100%
            { 

                setImage("ppl2.gif");

            }
        {
            return ((getObjectsInRange(2, InfectLv1.class)).size() != 0); 
        }
    }

...or not? compiles without errors, but nothing happens to them.

danpost

2011/6/11

#

remove a single set of brackets around your return statement -- try again. Also, not sure why you have World theWorld = getWorld(); statement in method.

kiarocks

2011/6/11

#

got rid of world statement and brackets- no errors but doesnt work still

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