What is the use of the final keyword in Java for example, MCQ

What is the usage of the final keyword in Java, eg MCQ?

What is the usage of the final keyword in Java, eg MCQ? In this article, we are going to fully explain What is the usage of the final keyword in Java, for example, MCQ? So let’s get started without wasting time.

What is a keyword in Java?

In the Java programming language, a keyword is a reserved word that has a specific meaning and cannot be used as an identifier (such as a variable name or function name).

Here is a list of some of the keywords in Java:

abstract, assert, boolean, break, byte, case, catch, char, class, constant, continue, default, do, duplicate, else, enumerate, extend, final, finally, float, to, goto, if, implements, import , instance of, int, interface, long, native, new, package, private, protected, public, return, short, static, strictfp, super, change, synchronized, this, throw, throw, transient, try, abort, volatile, While

Keywords are an important part of the Java syntax and are used to define the structure and behavior of a Java program.

What is the usage of the final keyword in Java, for example?

He final the keyword has several uses in the Java programming language:

  1. Final Variables: When a variable is declared, it means that its value cannot be changed. This is useful for variables that represent constants, such as final double PI = 3.14.
  2. Final Methods: When a method is declared, subclasses cannot override it. This can be used to prevent subclasses from changing the behavior of a method defined in a superclass.
  3. Final Classes: When a class is declared, it cannot be subclassed. This is often used for classes that represent concepts that should not be extended, such as the java.lang.String class.
  4. Finish Methods: The finalize() method is a special method that is called by the garbage collector when an object is about to be garbage collected. He finalize() Subclasses can override the method to provide necessary cleanup before the object is garbage collected. However the finalize() The method is not guaranteed to be called, so it should not be relied on for important tasks.

What is the use of the final keyword in Java, MCQ?

Here are some multiple choice questions about using the final keyword in java:

  1. What does it mean when a variable is declared? final in Java?

a) The value of the variable can be changed at any time b) The value of the variable cannot be changed after it is initialized c) The variable can only be used within the method in which it is declared d) It can only be accessed the variable by other classes in the same package

answer: b

  1. When a method is declared finalWhat does that mean?

a) Subclasses can override the method b) Subclasses cannot override the method c) The method can only be called from the class in which it is defined d) The method can only be called from other classes in the same package

answer: b

  1. When a class is declared finalWhat does that mean?

a) The class can be subclassed b) The class cannot be subclassed c) The class can only be used within the package it is defined in d) The class can only be accessed by other classes in the same package

answer: b

  1. What is the purpose of the finalize() the method in java?

a) To provide necessary cleanup before an object is garbage collected b) To ensure that an object is properly initialized before it is used c) To specify the order in which an object’s fields should be serialized d) To mark a method as part of the implementation of an interface

answer: a

How to use final class in Java?

to use a final class in Java, you must first define the class using the final keyword. Here is an example of a final class definition:

final class MyClass {
// class definition goes here
}

Once you have defined a final class, you cannot create a subclass of that class. This means that you cannot use the extends keyword to create a subclass of a final class.

Here is an example of how you could use a final class:

final class MyClass {
// class definition goes here
}

public class Main {
public static void main(String[] args) {
MyClass obj = new MyClass();
// use obj as needed
}
}

In this example, MyClass is a final class and cannot be subclassed, but can be instantiated and used like any other class. Is there anything else I can help with?

What is the use of the final keyword in inheritance?

He final The keyword can be used in inheritance to prevent a method from being overridden or a class from being subclassed.

If a method is declared final, cannot be overridden by subclasses. This can be useful if you want to ensure that a subclass doesn’t change the behavior of a method defined in a superclass.

For example:

class SuperClass {
public final void doSomething() {
// method implementation goes here
}
}
class SubClass extends SuperClass {
// this line will cause a compile-time error because doSomething() is declared final in the superclass
public void doSomething() {
// method implementation goes here
}
}

If a class is declared final, cannot be subclassed. This can be useful if you want to ensure that a class represents a concept that should not be extended.

For example:

final class MyClass {
// class definition goes here
}
// this line will cause a compile-time error because MyClass is declared final
class MySubClass extends MyClass {
// class definition goes here
}

He final a keyword can be used to improve the reliability and performance of Java programs by preventing unwanted code changes.

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2023

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