I want to make bubble shooter game and I have problem with generate bubbles at start. When trying to compile program, I have error: Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException.
public class MyPanel extends JPanel {
Init init;
public MyPanel(){
super();
init = new Init();
}
public void paint(Graphics g){
Dimension size = getSize();
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(Color.GRAY);
g2d.fillRect(0, 0, size.width, size.height - 70);
for(int j = 0; j < 10; j++)
for(int i = 0; i < 20; i++){
init.fields[i][j].b.paint(g); //here compiler shows error
}
}
}
public class Field {
private int x;
private int y;
private int r = 30;
public Baloon b;
public Field(int x, int y){
this.x = x*r;
this.y = y*r;
}
public void addBaloon(int n){
b = new Baloon(this.x, this.y, r, n);
}
}
public class Init {
Parser pr = new Parser();
private int r = pr.getRadius();
private int x = pr.getXDimension();
private int y = pr.getYDimension();
private int ni = pr.getColorRange();
Field[][] fields = new Field[x][y];
private int startX = 20;
private int startY = 10;
public Init(){
for(int yi = 1; yi<y; yi++){
for (int xi = 1; xi<x; xi++){
fields[xi][yi] = new Field(xi*r, yi*r);
}
}
for(int yi = 1; yi < startY; yi ++){
for(int xi = 1 ; xi < startX; xi++){
Random rand = new Random();
int n = rand.nextInt(ni);
fields[xi][yi].addBaloon(n);
}
}
}
}
You are initializing array from index 1:
for(int yi = 1; yi<y; yi++){
for (int xi = 1; xi<x; xi++){
fields[xi][yi] = new Field(xi*r, yi*r);
}
}
While accessing it from 0 like:
for(int j = 0; j < 10; j++)
for(int i = 0; i < 20; i++){
init.fields[i][j].b.paint(g); //here compiler shows error
}
Array index starts from 0 and goes upto n-1. So you need to initialize like:
for(int yi = 0; yi<y; yi++){
for (int xi = 0; xi<x; xi++){
fields[xi][yi] = new Field(xi*r, yi*r);
}
}