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Difference between abstract and final class?
Abstract class is built to promote inheritance whereas a final class is built to avoid inheritanceAn Abstract class can be extended by another class whereas a final class cannot be extended
How do you prevent inheritance in java?
If a class is declared as final, you can't inherit from it. If individual methods are declared final, then, if the class is inherited, these methods can't be changed in the inherited 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.
Why final method are used in java?
Final methods are used when a class is inheritable but should have some functions that must not be overridden for them to operate properly. This allows a class that can be inherited, but still have limits on its customization. Usually, final methods are declared so that a method that accepts a parameter of class A can accept a parameter of class B that inherits from A, and the designer of class A can still be certain that the method will operate as intended regardless of what the developer does in class B.
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).
What is difference between abstract class and interface in core java give brief answer with example?
Differences:Abstract class can also contain method definitions but an interface can contain only declarationsAll variables in an interface are by default public static and final whereas in Abstract class it is notAn interface can be considered as a pure abstract class that contains no method implementations and contains only declarations.
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.
What can be declared in an abstract class?
Abstract classes are to be extended until to a concrete class.Can have both abstract & non abstract methods.An Abstract class can not be instantiated.A non abstract class can be extended to an abstract class.If At least one abstract method present in a class then that class must be abstract.abstract & final modifiers can never be together.abstract classes can have both abstract methods & non abstract methods.
What is a specifier?
a specifier tells the JVM how to treat a particular class,method and variable while executing the program. For example, final classes cannot be extended and final methods cannot be overriden and final variables cannot be changed once declared. Likewise,static methods and variables can be accessed without having to instantiate an object for their class
Explain with an example program the uses of final keywords?
The Final keyword is used to ensure that the methods/variables are not modified/overridden in their child classes. ex: public class A { public void final getName(){ ... } } public class B extends A{ public void getName(){ ... } } While trying to compile class B, there would be compilation errors. Since the method getName in the parent class is final, it cannot be overridden in the child class.
Why final method are used?
Final methods in Java are used to prevent method overriding, ensuring that the behavior of a method remains consistent and cannot be altered by subclasses. This is particularly useful for maintaining the integrity of critical methods or when implementing security measures. By declaring a method as final, developers can also improve performance, as the compiler can optimize calls to these methods. Overall, final methods promote a clear design by restricting the extensibility of certain class behaviors.
How do you prevent class extending in java?
Declare the class as final. final class A{ ... }
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 -
A final class can have instances?
Yes. You cannot inherit a final class but very well instantiate a final class
When do you declare a class as final?
By using the final keyword in the class declaration statement. Ex: public final class Test {...}
Difference between super and final keyword?
this is a reference to the current classsuper is a reference to the super class of the current class (the class from which this class extends). You can use super.super if you want to access the second level class. (The class your parent class extends) The purpose of having thisand super keywords is to differentiate between methods and variables in classes that may have the same name as that in the parent class. Under such situations if we want to ensure that only the methods from a particular class only gets called we can use this and super.
How can you sort an arraylist of strings?
You can sort an ArrayList by using the sort method of the Collecions class (java.util.Collections). Assuming you have an ArrayList called foo: Collections.sort(foo);
Why would you make a class final in java?
You would make a class Final in Java if you do not want anybody to inherit the features of your class. If you declare a class as Final, then no other class can extend this class. Example: public final class X { .... } public class Y extends X { .... } Here Y cannot extend X because X is final and this code would not work.
Discuss final method and final classes?
a method declared final can not be overridden, and a class declared as final can not be extended by its sub class.
How can you create a class which cannot be inheritable?
Declare it final.
