Java By Comparison

Avoid Collection Modification During Iteration

class Inventory {

    private List<Supply> supplies = new ArrayList<>();

    void disposeContaminatedSupplies() {
        for (Supply supply : supplies) {
            if (supply.isContaminated()) {
                supplies.remove(supply);
            }
        }
    }
}

We iterate over arrays, lists, or other data structures all the time. Most of the time, we only read from those data structures—for instance, when creating an invoice from a list of ordered items or searching for an item in a list by name. But you need to be careful when you modify the structure. Otherwise, you risk crashing your program.

This code describes a fairly simple iteration over a data structure: a List of supplies. If a Supply isContaminated(), the inventory ...