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

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

What is the use of the final keyword in Java, for example, MCQ – In this article, we are going to fully explain What is the use of the final keyword in Java for example, MCQ so let’s start without wasting your time.

What is 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 a function name).

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

abstract, assert, boolean, break, byte, case, catch, char, class, const, continue, default, do, double, else, enum, extends, final, finally, float, for, goto, if, implements, import, instanceof, int, interface, long, native, new, package, private, protected, public, return, short, static, strictfp, super, switch, synchronized, this, throw, throws, transient, try, void, 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 use of the final keyword in Java for example?

The 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, it cannot be overridden by subclasses. 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. Finalize methods: The finalize() the method is a special method that is called by the garbage collector when an object is about to be garbage collected. The finalize() method can be overridden by subclasses to provide any necessary cleanup before the object is garbage collected. However, the finalize() method is not guaranteed to be called, so it should not be relied upon for important tasks.

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

Here are some multiple-choice questions on the use of 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 it is declared in d) The variable can only be accessed by other classes in the same package

Answer: b

2. When a method is declared final, what does it mean?

a) The method can be overridden by subclasses b) The method cannot be overridden by subclasses c) The method can only be called from within the class it is defined in d) The method can only be called from other classes in the same package

Answer: b

3. When a class is declared final, what does it 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

4. What is the purpose of the finalize() the method in Java?

a) To provide any 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 being part of the implementation of an interface

Answer: a

How to use the 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 might 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 it can be instantiated and used like any other class. Is there anything else I can help with?

What is the use of final keyword in inheritance?

The final 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, it cannot be overridden by subclasses. This can be useful if you want to ensure that the behavior of a method defined in a superclass is not changed by a subclass.

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, it 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
}

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

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