Question

In my processing program, I added an object into a global ArrayList called items in my draw function.

Here is the class.

class Obj {
    String name;
    Obj(String name) {
        self.name = name;
    }
}

Here is my draw function.

void draw () {
    items.add(new Obj("Bob"));
}

I tried printing the size of items in my mouseClicked() function into the console, but I keep getting 0.

void mouseClicked () {
    print(items.size());
} 

Why?

The ArrayList is declared at the top of my file after my class:

ArrayList<Obj> items = new ArrayList<Obj>();

Answer 1

There are a couple of things which aren’t quite there yet:

1. self.name = name; should be this.name = name;
2. You’re creating tons of objects (based on framerate), but only checking the size of the array in mouseCliked() (also you might want to use println() instead).

Try this:

ArrayList<Obj> items = new ArrayList<Obj>();

void setup(){

}
void draw () {

}
void mouseClicked () {
  items.add(new Obj("Bob"));
  println("items size: " + items.size());
} 
class Obj {
    String name;
    Obj(String name) {
        this.name = name;
    }
}