What keywords are used when a class inherits from another class in java?

In Java, class inheritance uses the extends keyword, allowing subclasses to inherit members of the parent class and achieve code reuse, scalability and polymorphism. It should be noted that subclasses cannot access private members of the parent class, and access rights cannot be lower when overriding parent class methods. If the parent class is an abstract class, the subclass must implement its abstract method.

Keywords for class inheritance in Java

In Java, keys used when a class inherits another class The words are extends. It associates a subclass with a parent class, allowing the subclass to access and override methods and fields in the parent class.

Specific usage

public class ChildClass extends ParentClass {

    // 子类的内容

}

In this example, ChildClass inherits ParentClass. This means that ChildClass can access and override all non-private members in ParentClass.

Benefits

Class inheritance provides the following benefits:

• Reusable code: subclasses can directly use methods in the parent class and fields to avoid writing the same code repeatedly.
• Extensibility: Subclasses can extend parent classes and add new methods and fields to achieve different functions.
• Polymorphism: Subclasses and parent classes can be used interchangeably because they have the same interface.

Notes

You need to pay attention to the following when using inheritance:

• Subclasses cannot access private members of the parent class.
• If a subclass overrides a method of the parent class, the access rights of the subclass method cannot be lower than that of the parent class method.
• If the parent class is an abstract class or interface, then the subclass must implement or override all abstract methods in the parent class.

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