I don't see the problem here. Maybe someone can explain. I'm playing around with inheritance, but some things are still hard to see.
I have a World called 'Title' that creates 3 objects.
1) an object of class Start (so that the start-button can get pressed and do sth. )
2) an object of class 'Quest'
3) an object of class 'Quest1' (that inherits from class 'Quest')
In 'Quest' is a method 'activateQuest'. 'Quest1' inherits this method. Goal was to make the object of 'Quest1' or 'Quest2,3,4...' the new 'Quest'-object in 'Title'.
During runtime I encounter a NullPointerException for line7 in 'Quest'. Is it a problem with 'this'? Or a problem with 'Quest1' being only a 'Quest'-object through inheritance?
public class Title extends World
{
Start start = new Start();
Quest quest = new Quest();
Quest1 quest1 = new Quest1();
public Title()
{
super(600, 400, 1);
prepare();
}
public void act()
{
if (Greenfoot.mouseClicked(start))
{
System.out.println("Started!");
quest1.activateQuest();
}
}
public void setQuest(Quest quest)
{
this.quest = quest;
}
private void prepare()
{
addObject(start, 297, 228);
}
}public class Quest extends Actor
{
public void activateQuest()
{
World myWorld = getWorld();
Title title = (Title)myWorld;
title.setQuest(this);
}
}