size = size in a constructor

class Box {
    int size;
    String name;

    Box(int size, String name) {
        size = size;
        this.name = name;
    }
}

public class Main {
    public static void main(String[] args) {
        Box b = new Box(7, "crate");
        System.out.println(b.size + " " + b.name);
    }
}