Error changing array for arraylist

Programming Questions

chocolate..

Error changing array for arraylist

in Programming Questions • 1 year ago

Hi all!

I have an array but I changed it to arraylist because I don't want it to be fixed. After this change I am getting an error that I don't understand.

This is the part of the code that has the problem, exactly the second line:

for (int i = 0; i < pl.length; i++) {

for (int j = 0; j < gF.size(); j++) pl[i].setNuevaDireccion(gF[j].x, gF[j].y, gF[j].radius, 1500*gF.size(), .4);

for (int j = 0; j < pl.length; j++) {

if ( j != i) pl[i].setNuevaDireccion(pl[j].x, pl[j].y, pl[j].radius, 2000, .6);

}

pl[i].setNuevaPosicion();

}

The second line was working perfect previous this change:

From:

for (int j = 0; j < gF.length; j++) pl[i].setNuevaDireccion(gF[j].x, gF[j].y, gF[j].radius, 1500*gF.length, .4);

To:

for (int j = 0; j < gF.size(); j++) pl[i].setNuevaDireccion(gF[j].x, gF[j].y, gF[j].radius, 1500*gF.size(), .4);

but now I obtain this error "The type of expression must be an array type but it resolved to ArrayList"

any idea??

Replies(3)

calsign

Re: Error changing array for arraylist

1 year ago

You are trying to access the ArrayList's elements with the bracket (" [x]"), array syntax, while ArrayLists' elements must be accessed with ArrayList.get(x).

PhiLho

Re: Error changing array for arraylist

1 year ago

Also array list access has a (little) cost, so you better get the object of the list once before the expression, and use it after.
Something like:

for (int j = 0, s = gF.size(); j < s; j++)
{
YourClass gfItem = gF.get(i); // Supposing you declared ArrayList<YourClass>
pl[i].setNuevaDireccion(gfItem.x, gfItem.y, gfItem.radius, 1500*s, .4);
}

or, better since you don't use the index:

for (YourClass gfItem : gF)
{
pl[i].setNuevaDireccion(gfItem.x, gfItem.y, gfItem.radius, 1500*gF.size(), .4); // Can get size() value before the loops, but it is fast enough
}

Of course, replace YourClass by the class name of gF[j]

chocolate..

Re: Error changing array for arraylist

1 year ago

Thank you guys, it is working now! I didn't know I can't access an arraylist element with []