What does protected mean in java?

In Java, the "protected" access modifier grants access to a specific class and its subclasses, including classes in the same package: Same-package access: Allows classes in the same package to access protected content . Subclass access: Allow subclasses to access protected content, regardless of whether the subclass is in the same package or a different package. Access is not allowed in other packages: Except for classes and subclasses in the same package, classes in other packages cannot access protected content.

The meaning of protected in Java

In Java access control, "protected" is an access modifier , which grants access to a specific class and its subclasses, including classes in the same package.

The specific meaning is as follows:

• #Same package access: Similar to the default access permissions, protected allows access to all classes in the same package The content it modifies.
• Subclass access: Content modified by protected can be accessed by its subclasses, regardless of whether the subclasses are in the same package or in different packages.
• Other packages are not allowed to access: Except for classes and subclasses in the same package, classes in other packages cannot access protected content.

Advantages of protected:

• Improve code reusability: By allowing subclasses to access protected content, Code reuse can be achieved and the writing of duplicate code can be reduced.
• Enhanced encapsulation and security: Compared with public access, protected restricts access to content, thereby improving encapsulation and security, but still allows its use in subclasses.
• Promote inheritance and polymorphism: Protected access allows subclasses to inherit and override protected methods, thereby achieving polymorphism.

Use cases of protected:

• # is used to define methods and fields in the base class that can be overridden by subclasses, but other classes cannot access.
• is used to design frameworks that allow third parties to extend and modify functionality but still control access to key implementations.
• is used to create auxiliary classes in the same package. These classes can use protected modified content.

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