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What is the purpose of using final keyword with a class declaration?
Wiki User
∙ 8y ago
The final keyword is used in several different contexts as a modifier meaning that what it modifies cannot be changed in some sense. public final class String This means this class will not be subclassed, and informs the compiler that it can perform certain optimizations it otherwise could not. It also provides some benefit in regard to security and thread safety. The compiler will not let you subclass any class that is declared final. You probably won't want or need to declare your own classes final though. You can also declare that methods are final. A method that is declared final cannot be overridden in a subclass. The syntax is simple, just put the keyword final after the access specifier and before the return type like this: public final String convertCurrency() You may also declare fields to be final. This is not the same thing as declaring a method or class to be final. When a field is declared final, it is a constant which will not and cannot change. It can be set once (for instance when the object is constructed, but it cannot be changed after that.) Attempts to change it will generate either a compile-time error or an exception (depending on how sneaky the attempt is). Fields that are both final, static, and public are effectively named constants.
Wiki User
∙ 15y ago
Wiki User
∙ 8y agoThe final keyword when applied to a class prevents the class from being sub-classed.
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What does the final keyword mean in front of a variable a method a class?
When used in a class declaration, the final keyword means the a class can't be subclassed. In other words, no other class can extend (inherit) a final class, and any attempts to do so will give you a compiler error. The final keyword prevents a method from being overridden in a subclass. Final methods are usually placed in classes where you don't want anyone who is extending your code to meddle with a certain piece of functionality. Declaring a variable with the final keyword makes it impossible to reassign a different value to that variable once it has been initialized with an explicit value -
What if a final keyword is applied to a function?
The final keyword in JAVA means that the class can no longer be derived, i.e. it cannot be used as a base class for a new child class.If you declare a method as final, this method cannot be overridden in any of the child class that may extend this class.
How do you prevent method overriding in java?
Use the word "final" directly preceding your method declaration. The presence of final keyword directs java to ensure that, this particular method would not be overridden by any of its child classes.
What is the relationship between inheritance methods and the keyword final?
They are inversely related. That is: If you declare a method as final you cannot overridden in the child class If you declare a class as final you cannot inherit it in any other class.
Can you have a final abstract class?
No. The abstract keyword means that you cannot instantiate the class unless you extend it with a subclass. The final keyword means that you cannot create subclasses of that class.Combining them would lead to an unusable class, so the compiler will not let this happen.
When do you declare a class as final?
By using the final keyword in the class declaration statement. Ex: public final class Test {...}
What does the final keyword mean in front of a variable a method a class?
When used in a class declaration, the final keyword means the a class can't be subclassed. In other words, no other class can extend (inherit) a final class, and any attempts to do so will give you a compiler error. The final keyword prevents a method from being overridden in a subclass. Final methods are usually placed in classes where you don't want anyone who is extending your code to meddle with a certain piece of functionality. Declaring a variable with the final keyword makes it impossible to reassign a different value to that variable once it has been initialized with an explicit value -
Can you make a class final in java?
yes of course... using the final keyword
How prevent inheritance in java without final?
Make the constructor private. Uhm, how would you make a instance of this class then? Why don't you want inheritance? I don't understand!Answer:You can create the class without the public declaration. In such a case the access for that class would be default and hence you cannot extend that specific class outside its package. Still you can extend this class within its package.The purpose of having the final keyword is to ensure that the class is not inherited. doing it without final is like touching your nose around your head when you can do it straightaway...
What if a final keyword is applied to a function?
The final keyword in JAVA means that the class can no longer be derived, i.e. it cannot be used as a base class for a new child class.If you declare a method as final, this method cannot be overridden in any of the child class that may extend this class.
How do you prevent method overriding in java?
Use the word "final" directly preceding your method declaration. The presence of final keyword directs java to ensure that, this particular method would not be overridden by any of its child classes.
What is the relationship between inheritance methods and the keyword final?
They are inversely related. That is: If you declare a method as final you cannot overridden in the child class If you declare a class as final you cannot inherit it in any other class.
Can you have a final abstract class?
No. The abstract keyword means that you cannot instantiate the class unless you extend it with a subclass. The final keyword means that you cannot create subclasses of that class.Combining them would lead to an unusable class, so the compiler will not let this happen.
What is the final keyword in Java?
The final keyword precedes a declared constant which after Instantiation cannot be modified. Examples. final double PI = 3.14; PI = 1234; // does not compile //or final double ONE; ONE = 1; // Instantiated ONE = 2; // does not compile ---------------------------------------- final keyword can also apply to a method or a class. When applied to a method - it means the method cannot be over-ridden. Specially useful when a method assigns a state that should not be changed in the classes that inherit it, and should use it as it is (not change the method behaviour). When applied to a class it means that the class cannot be instantiated. A common use is for a class that only allows static methods as entry points or static final constants - to be accessed without a class instance. A good example is Java's: public final class Math extends Object
What is mean by Final?
final is a Java keyword. It is used to:> Mark a variable as final which prevents its value from being changed> Mark a class as final to prevent it from being extended> Mark a method as final to avoid it from beingoverridden
What happens if a final keyword is applied to function?
A final function can not be overridden for any subclass. This means any class which extends our class with a final function can not redefine the functionality of our final function. if you have: public class Top{ public final doSomething(){ System.out.println("hi"); } } You can not do this: public class Buttom extends Top{ public final doSomething(){ // NO! YOU CAN'T CHANGE THIS FUNCTION System.out.println("good-bye"); // THIS CODE DOES NOT COMPILE } }
What are the usages of keyword final in java?
It's a built-in keyword that defines an entity that cannot be later modified. It can be used in different aspects within your code (like setting a 'final' class, method (function), or variable).
