How to Efficiently Retrieve Objects from ArrayLists Based on Specific Properties?

Retrieving Objects from ArrayLists Based on Properties

In object-oriented programming, you often encounter scenarios where you need to locate an object with a specific property amidst a collection. This can be particularly useful in frameworks like Java EE, where you might be working with POJOs and need to retrieve objects from an in-memory cache.

Consider a scenario where you're managing a list of Carnet objects, each of which possesses properties like codeTitre, nomTitre, and codeIsin. Suppose you need to find a particular Carnet object based on its codeIsin. To achieve this, you can leverage the power of Java's streams:

public static Carnet findByCodeIsIn(Collection<Carnet> listCarnet, String codeIsIn) {
    return listCarnet.stream().filter(carnet -> codeIsIn.equals(carnet.getCodeIsin())).findFirst().orElse(null);
}

This code snippet utilizes streams to efficiently search through the collection of Carnet objects, filtering out those that don't match the given codeIsIn criteria. By leveraging the findFirst() method, you retrieve the first matching object, or null if no object is found.

You may also encounter situations where you need to find objects with different properties or across multiple types of objects. To address this, you can introduce a utility class like FindUtils:

public final class FindUtils {
    public static <T> T findByProperty(Collection<T> col, Predicate<T> filter) {
        return col.stream().filter(filter).findFirst().orElse(null);
    }
}

This utility class provides a generic method that can be used to search for objects based on any specified criteria.

Furthermore, you can create specific utility classes for each object type, like CarnetUtils:

public final class CarnetUtils {
    public static Carnet findByCodeTitre(Collection<Carnet> listCarnet, String codeTitre) {
        return FindUtils.findByProperty(listCarnet, carnet -> codeTitre.equals(carnet.getCodeTitre()));
    }

    // Similar methods for finding by other properties
}

By employing these utility classes, you can easily and flexibly search for objects within your ArrayLists, regardless of their specific properties.

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