I am working on a dialoguebox with a working "next" button that changes the line of text being shown, everytime it's clicked. In the "Nextbutton" class, i have managed to make a variable where if you click the next button, a counter goes up. The problem arises when i try to bring that variable from my 'Nextbutton' class over to 'Dialoguebox' class. I already made a string containing the script. When i try to start the game it gave me a "java.lang.NullPointerException", so i did some experimenting the world class but i can't wrap my head around it, can someone please help me?
code Nextbutton:
code Dialoguebox:
code world:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 | public class Nextbutton extends Scriptje{ public boolean mouseDown; public int currentline; private GreenfootImage image; public boolean lineChanged = false; /** * Act - do whatever the Nextbutton wants to do. This method is called whenever * the 'Act' or 'Run' button gets pressed in the environment. */ public Nextbutton() { mouseDown = false; verkleinButton(); image = getImage(); } public void act() { if (!mouseDown && Greenfoot.mouseClicked(this)) { currentline++; getWorld().showText("currentline: " + currentline, 200, 100); //verwijder dit zodra dat het script werkt lineChanged = true; } } private void verkleinButton() { GreenfootImage img = new GreenfootImage("nextbutton.png"); img.scale(img.getWidth()/10, img.getHeight()/10); setImage(img); }} |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | public class Dialoogbox extends Scriptje{ public String[] lines={"line 1", "line 2", "line 3?", "line 4"}; private int followscript; public boolean scriptChanged = false; /** * Act - do whatever the Dialoogbox wants to do. This method is called whenever * the 'Act' or 'Run' button gets pressed in the environment. */ // dialoogbox (klasse van knopje) public Dialoogbox() { followscript = getWorld().getObjects(Nextbutton.class).get(0).currentline; scriptChanged = getWorld().getObjects(Nextbutton.class).get(0).lineChanged; } public void script(){ if (!scriptChanged) { GreenfootImage image = new GreenfootImage(lines[followscript], 24, Color.BLACK, new Color(255,255,255)); } } public void act() { }} |
1 2 3 4 5 6 7 8 9 10 | public MyWorld() { super(600, 400, 1); prepare(); setPaintOrder(Nextbutton.class, Dialoogbox.class, Verkoper.class, Klant.class); setBackground("wereldkaart.jpg"); toonTekst("Kies het continent dat je wilt bezoeken:", getWidth() / 2, getHeight() / 4); Nextbutton knopje = new Nextbutton(); Dialoogbox boxje = new Dialoogbox(knopje); } |
