PHP Object-oriented final class and final method

Final---Used for classes, methods, and before.
The final class---cannot be inherited.
The final method---not be overwritten.
The final class cannot be inherited.
If we do not want a class to be inherited, we use final to modify the class. This class will not be inherited. For example, we set up the math class, which involves the mathematical calculation methods we want to do, the algorithms are not necessary to modify, and there is no need to be inherited, we set it to the final type.

<? Declares a final class math final class math{public static $PI = 3.14; public Function __tostring () {return "This is the math class. "; } } $math = new Math (); Echo $math; Declaring a class Supermath inherits from the math class Supermath extends Math {}//executes an error and the final class cannot be inherited.?>

Program Run Results

Fatal Error:class Supermath may not inherit from final Class (Math) in E:\PHPProjects\test.php on line 14

Final method cannot be overridden
If you do not want a method in the class to be overridden by the quilt class, we can set this method to be the final method, just precede the method with the final modifier.

If this method is overridden by the quilt class, an error will occur.

<? Declares a final class, math class math{public static $PI = 3.14, Public function __tostring () {return "This is the math category. "; } Public final function Max ($a, $b) {return $a > $b? $a: $b;}} Declares that the class Supermath inherits from the math class Supermath extends Math {public final function max ($a, $b) {}}//executes an error and the final method cannot be overridden.?>

Program Run Results

Fatal Error:class Supermath may not inherit from final Class (Math) in E:\PHPProjects\test.php on line 16