Unlock the Power of Java’s compute() Method
When working with HashMaps in Java, you need a way to update values efficiently. That’s where the compute() method comes in – a game-changer for manipulating your data.
Understanding the compute() Syntax
The compute() method takes two essential parameters: key
and remappingFunction
. The key
is the identifier associated with the value you want to update, while the remappingFunction
is a BiFunction that calculates the new value.
How compute() Works Its Magic
This method returns the new value linked to the specified key
. If no value is associated with the key
, it returns null
. But here’s the catch: if the remappingFunction
returns null
, the mapping for the key
is removed.
A Real-World Example: Discounts Made Easy
Let’s say you have a HashMap called prices
that stores the costs of various items. You want to apply a 10% discount to the price of “Shoes”. Using the compute() method, you can achieve this with a lambda expression:
prices.compute("Shoes", (key, value) -> value - value * 10/100);
This expression reduces the old value of “Shoes” by 10% and returns the updated price. The compute() method then associates this new value with the “Shoes” key.
Simplifying Your Code
According to Java’s official documentation, the HashMap merge() method is a simpler alternative to compute(). If you’re looking for more ways to optimize your code, explore other HashMap methods like computeIfAbsent() and computeIfPresent().