Final Keyword In Java : Introduction
- Java final keyword is used as prevention, i.e. it restricts user.
- Java final keyword has three uses :
- It can be used with variables to prevent their values from being changed.
- It can be used to prevent overriding.
- It can be used to prevent inheritance.
Final Keyword In Java : The Discussion
1) final with Variables
- If any variable is made final , it restricts the user to changes its value i.e. the content of variable cannot be changed.
Note : A blank variable can also be declared as final and it will be initialized in constructor only, because constructor are invoked as soon as object of that class is created.
- We tried to change the final variable and compiler throws an error which is stated in output.
2) final with Method
- The only purpose of using final with method is to prevent method overriding.
- When a method is declared as final then it cannot be overridden. If we try to do so , we get a compile time error. Let us understand with an example.
- We tried to override a final method and got an error.
3) final with Class
- A class preceded with final keyword cannot be inherited.
- Final keyword prevents a class from getting inherited and also implicitly declares all of its methods as final.