Arraylist Processing

Programming Questions

stavrosdee

in Programming Questions • 1 year ago

Hi to all.

Based on the following example, I would like to know how it is possible to create a line that connects the first added ellipse with the second added ellipse (and then the second with the third, the third with the fourth, and so on.

http://www.processing.org/learning/topics/arraylistclass.html

I have tried the following but it connects the newly added ellipse with all the previous ellipses, and I want to avoid that.

(The returnPosX and returnPosY is a return statement from the ball class that gives me back the position of x and y).

for (int i = balls.size()-1; i >= 0; i--) {

Ball ball = (Ball) balls.get(i);

for (int j = balls.size()-1; j >= 0; j--) {

Ball ball2 = (Ball) balls.get(j);

line(ball.returnPosX(),ball.returnPosY(), ball2.returnPosX(), ball2.returnPosY());

ball.move();

ball.display();

}

Replies(2)

quarks

Re: Arraylist Processing

1 year ago

Obviously I can't test it but the code below should work.

Ball ball1, ball2;
for (int i = balls.size()-1; i >= 0; i--) {
// Only draw the line if we have not reached the last ball
if (i > 0) {
ball1 = (Ball) balls.get(i);
ball2 = (Ball) balls.get(i-1);
line(ball.returnPosX(), ball.returnPosY(), ball2.returnPosX(), ball2.returnPosY());
}
// Move the ball and display it
ball1.move();
ball1.display();
}

stavrosdee

Re: Arraylist Processing

1 year ago

Hey thanks for the tip! It worked - sort of. I had to change the following (ball1 = (Ball)...outside the if statement):

Ball ball1, ball2;
for (int i = balls.size()-1; i >= 0; i--) {
ball1 = (Ball) balls.get(i);
if (i > 0) {
ball2 = (Ball) balls.get(i-1);
line(ball.returnPosX(), ball.returnPosY(), ball2.returnPosX(), ball2.returnPosY());
}
// Move the ball and display it
ball1.move();
ball1.display();
}

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