Java By Comparison

Avoid Compute-Intense Operations During Iteration

class Inventory {

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

    List<Supply> find(String regex) {
        List<Supply> result = new LinkedList<>();
        for (Supply supply : supplies) {
            if (Pattern.matches(regex, supply.toString())) {
                result.add(supply);
            }
        }
        return result;
    }
}

When you iterate over a data structure, you need to be careful with what kind of operations you perform. If you do something that is compute-intense, it can easily turn into a performance pitfall. The code above shows a typical example for this with the method find() that locates Supply objects with a regular expression.

In Java, or in any other programming language, you’ll build query strings ...