Characteristics of final keyword in java

The final keyword in Java is used to declare unmodifiable values ​​or objects. It has the following characteristics: Constant declaration: declares an unmodifiable value and must be initialized at the time of declaration. Immutable object reference: The object reference cannot be changed after creation, and the object content is mutable. Method overriding restrictions: final methods cannot be overridden by subclasses. Classes are not inheritable: final classes cannot be inherited. Performance optimization: The compiler can optimize constant values ​​to increase execution speed. Thread safety: final variables and objects are safe in multi-threaded environments.

Characteristics of the final keyword in Java

The final keyword is used in Java to declare constants or immutables Object. It is an access modifier with the following characteristics:

1. Constant declaration

• Constant is an unmodifiable value and is declared using the final keyword.
• Constant must be initialized when declared.

2. Immutable objects

• The reference of a final object cannot be changed after it is created.
• The contents of the object itself can be mutable, but the reference always points to the same object.

3. Method rewriting restrictions

• Methods declared as final cannot be overridden by subclasses.
• This ensures that the behavior defined by the parent class will not be changed in the child class.

4. Classes cannot be inherited

• Classes declared as final cannot be inherited.
• This prevents the creation of subclasses of the class and ensures the uniqueness of the class's features.

5. Performance Optimization

• The final keyword can optimize compiler performance because it allows the compiler to determine constant values ​​at compile time.
• This can improve the execution speed of the program.

6. Thread safety

• final variables and objects are thread-safe in a multi-threaded environment.
• Because their values ​​or references cannot be changed, concurrent access problems are avoided.

Usage scenarios

The final keyword is usually used in the following scenarios:

• Define constants, such as mathematical constants or applications configuration.
• Create immutable objects, such as strings or immutable collections.
• Limit overriding of methods, such as core algorithms or security operations.
• Prevent class inheritance, such as classes used to implement the singleton pattern.

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