What are the applications of generic methods in Java EE development?

In Java EE development, generic methods can create methods suitable for different types of parameters, providing the following applications: operating the database, such as using the generic methods provided by the EntityManager class to find and persist entities. Process collections, such as using the generic methods defined by the List interface to operate on list elements, or using the generic methods defined by the Map interface to operate on key-value pairs in the map. The advantages of generic methods in Java EE development include code reusability, code security, and code simplicity.

Application of generic methods in Java EE development

Generic methods provide a way to create parameters that can be used for different types Methods. This allows developers to write more versatile and reusable code. In Java EE development, generic methods are widely used:

Operation database

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• EntityManager class](https: //docs.oracle.com/javaee/7/api/javax/persistence/EntityManager.html) provides generic methods find() and persist() for finding and persistent entities.
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• CriteriaBuilder class](https://docs.oracle.com/javaee/7/api/javax/persistence/criteria/CriteriaBuilder.html) allows the creation of type-safe queries, Among them, the generic methods equal() and lessThan() can be used.

Processing collections

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• List interface](https://docs.oracle.com/javase/8 /docs/api/java/util/List.html) defines the generic methods add(), remove() and contains() for Action list element.
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• Map Interface](https://docs.oracle.com/javase/8/docs/api/java/util/Map.html) defines generic methodsput(), get() and containsKey() are used to operate key-value pairs in the map.

Practical case

Finding entities

public <T> T findEntity(Class<T> entityClass, Object id) {
    return entityManager.find(entityClass, id);
}

Creating type-safe queries

public <T> CriteriaQuery<T> createQuery(Class<T> resultClass) {
    CriteriaBuilder cb = entityManager.getCriteriaBuilder();
    return cb.createQuery(resultClass);
}

Using collection generic methods

public <T> List<T> addAllToList(List<T> list, Collection<T> elements) {
    list.addAll(elements);
    return list;
}

Advantages

• Code Reusability: Generic methods can be used for different types of data, eliminating the need to create multiple specific methods dedicated to different types.
• Code safety: Generic methods enforce the use of specific type parameters, thus preventing compile-time errors and run-time type conversion errors.
• Code simplicity: Using generic methods can reduce redundant code and make the code more concise.

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