You may have come across some complex, hard-to-read Boolean expressions in your codebase and wished they were easier to understand. For example, let's say we want to decide whether a pizza is fantastic:
// Decide whether this pizza is fantastic. if ((!pepperoniService.empty() || sausages.size() > 0) && (useOnionFlag.get() || hasMushroom(ENOKI, PORTOBELLO)) && hasCheese()) { ... } |
A first step toward improving this is to extract the condition into a well-named variable:
boolean isPizzaFantastic = (!pepperoniService.empty() || sausages.size() > 0) && (useOnionFlag.get() || hasMushroom(ENOKI, PORTOBELLO)) && hasCheese(); if (isPizzaFantastic) { ... } |
However, the Boolean expression is still too complex. It's potentially confusing to calculate the value of isPizzaFantastic from a given set of inputs. You might need to grab a pen and paper, or start a server locally and set breakpoints.
Instead, try to group the details into intermediate Booleans that provide meaningful abstractions. Each Boolean below represents a single well-defined quality, and you no longer need to mix && and || within an expression. Without changing the business logic, you’ve made it easier to see how the Booleans relate to each other:
boolean hasGoodMeat = !pepperoniService.empty() || sausages.size() > 0; boolean hasGoodVeggies = useOnionFlag.get() || hasMushroom(ENOKI, PORTOBELLO); boolean isPizzaFantastic = hasGoodMeat && hasGoodVeggies && hasCheese(); |
Another option is to hide the logic in a separate method. This also offers the possibility of early returns using guard clauses, further reducing the need to keep track of intermediate states:
boolean isPizzaFantastic() { if (!hasCheese()) { return false; } if (pepperoniService.empty() && sausages.size() == 0) { return false; } return useOnionFlag.get() || hasMushroom(ENOKI, PORTOBELLO);
} |
