Core Java - Interview Questions and Answers for 'Final' | Search Interview Question

Core Java - Interview Questions and Answers for 'Final' - 51 question(s) found - Order By Rating

Q1. If we have a return statement inside the finally block, Then what will happen ?

Ans. Returning from inside a finally block will cause exceptions to be lost. A return statement inside a finally block will cause any exception that might be thrown in the try block to be discarded.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve exception handling finally block Asked in 1 Companies}

Q2. Can constructors be final ?

Core Java

Ans. No. They are never inherited and therefore are not subject to hiding or overriding.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve constructor final final constructor Asked in 1 Companies}

Q3. Are final methods faster than regular instance methods ?

Core Java

Ans. Yes. As they cannot be overridden , there is no use of virtual table concept which is used for dynamic binding resolution.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve final methods final keyword expert}

Q4. What could be the reasons for restricting inheritance using final class ?

Core Java

Ans. 1. Enforcing composition over inheritance
2. Restricting overriding of certain methods
3. Final methods are faster than regular instance methods
4. Enforcing Immutability

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve final class reasons for final class restricting inheritance object oriented programming (oops) oops concepts expert}

Q5. Does use of Final class enforces composition over Inheritance in Java ?

Core Java

Ans. Yes, to a certain extent. But the objective for Final class could be beyond just enforcing composition as certain classes might have been created without inheritance or composition in mind.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve final class composition object oriented programming (oops) oops concepts inheritance object oriented programming (oops) oops concepts composition object oriented programming (oops) oops concepts vs inheritance object oriented programming (oops) oops concepts expert}

Q6. Why Java has final class ?

Core Java

^{This question was recently asked at 'Avis'.This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve final class final keyword Asked in 1 Companies basic}

Q7. What will happen if there is an exception in Java finally block ?

Core Java

Ans. The regular behavior of exception handling will occur. It will look for any immediate catch handler and if none is provided, it would be transmitted to the callers until a catch handler is found or it's out of main function.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve exceptions finally}

Q8. What will the following code print and Why

class Class1 {
static{
System.out.println("Wow");
}
public static final int xyz=1;
}

class Class2{
public static void main(String[] args) {
System.out.println(String.valueOf(Class1.xyz));
}
}

Core Java

Ans. 1

Reason being that Class1.xyz is replaced with 1 during pre compilation only and a reference to Class1 is never made.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve static final pre compilation}

Q9. How different is it when final applied to variables and object references ?

Core Java

Ans. final when assigned to object references doesn't make them immutable. It means that the references cannot be de-referenced.

final when applied to variables means that the value cannot be changed.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve final keyword final variable}

Q10. When we say final x = 10, is the reference final or the value ?

Core Java

Ans. final keyword have meaning only to referenced and not the value. It means that the specified reference cannot be dereferenced. It doesn't control the value assigned to the memory that's being referenced. This is the reason that final object references doesn't mean that the object is immutable but means that the reference cannot be changed to point to new object.

In case of primitive types too, when we assign a reference to another, values are passed and not the object reference, and hence a new placeholder is created in memory with the same value. That is why final to that context means that you cannot change the assigned memory and there is no way we can have that memory place have another value.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve final keyword final variables references}

Q11. Is String final in Java ?

Core Java

Ans. Strings are immutable in Java and not final.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve is string final final string immutable immutability immutability}

Q12. What is the difference between being final and being immutable ? Are string final or immutable in Java ?

Core Java

Ans. Being final in the sense of objects or object reference means that the reference cannot be reassigned to a different object whereas being immutable means that the object contents cannot be changed.

Strings in Java are immutable.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve string immutable immutability final vs immutable immutability}

Q13. Will the following code compile ?

final HashMap hm = new HashMap();
hm.put("Ravi", 221);

Core Java

Ans. Yes, it will compile without error. final in this context means that the reference hm cannot be assigned to a new hash map but didn't restrict from changing the state of collection already held by hm.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve final final variable Asked in 1 Companies}

Q14. How do we define constant variables in Java ?

Core Java

Ans. By using static and final modifiers.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve constant variables static final basic frequent}

Q15. What is the use of final keyword ?

Core Java

Ans. final keyword is a modifier that means differently when applied to variables, methods and classes.

1. Final variable cannot be changed once initialized
2. Final method cannot be overridden
3. Final class cannot be sub classed

Sample Code for final variable

Sample Code for final method

Sample Code for final class

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve final final keyword Asked in 1 Companies Basic frequent}

Q16. Which of following is / are valid static final declaration ?

public static final String MAX_NUM = "10";
public static final Object NULL = null;
public static final MathContext MATH_CONTEXT = new MathContext(2,RoundingMode.CEILING);

Core Java

Ans. All are valid declarations.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve static final constants basic}

Q17. What is a blank final variable ? Can we initialize a blank final variable ?

Core Java

Ans. A final variable that is not initialized while declaration is a blank final variable.

Yes, we can initialize it within a constructor.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve blank final variable final variable}

Q18. Would you consider creating a constant name for "null" ?

Core Java

Ans. Objective of constant variable is to provide a context to the value and provide a single point of change. In terms of context, i don't see much need for having constant name for null as null is already self explanatory. In terms of providing single point of change, it doesn't make much sense as it would necessitate that all such placeholders either hold null or a common value.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve constant variables static final variable java conventions java naming conventions}

Q19. If we have to maintain a value "31" denoting "number of days in a month" as constant variable, Which of the following is the best constant name and Why ?

THIRTY_ONE
NUMBER_OF_DAYS_IN_MONTH
NUMBER_OF_DAYS_IN_MONTH_31

Core Java

Ans. NUMBER_OF_DAYS_IN_MONTH_31

Constant should be such that it uniquely identifies the value it holds and context of the value. THIRTY_ONE uniquely identifies the value but doesn't express the context. NUMBER_OF_DAYS_IN_MONTH expresses the context but doesn't specify the value clearly as different month can have different number of days.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve constant variables static final variable java conventions java naming conventions}

Q20. If we have to maintain a value "7" denoting "number of days in a week" as constant variable, Which of the following is the best constant name and Why ?

SEVEN
NUMBER_OF_DAYS_IN_WEEK
NUMBER_OF_DAYS_IN_WEEK_7

Core Java

Ans. NUMBER_OF_DAYS_IN_WEEK

Constant should be such that it uniquely identifies the value it holds and context of the value. SEVEN uniquely identifies the value but doesn't express the context.

Though NUMBER_OF_DAYS_IN_WEEK and NUMBER_OF_DAYS_IN_WEEK_7 makes sense in terms of unique value identification and context but 7 at the end of constant name appears useless as all weeks have 7 days and hence it's the only value it can hold. If it would have been "number of days in a month", it would have made sense to include number of days at the end like

NUMBER_OF_DAYS_IN_MONTH_30
NUMBER_OF_DAYS_IN_MONTH_31
NUMBER_OF_DAYS_IN_MONTH_27
NUMBER_OF_DAYS_IN_MONTH_28

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve constant variables static final variable java conventions java naming conventions}

Q21. Will finally run if we have return statement and it exits the method early ?

Core Java

Ans. finally will execute in all graceful situations - graceful executions as well as graceful exceptions. The only situation when finally block won't execute is when the app is abruptly stopped, killed or unplugged.

Sample Code for finally

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve finally Intermediate}

Q22. When is the situation when finally section won't execute ?

Core Java

Ans. If the process / app is abruptly killed or terminated.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve exception handling finally Asked in 2 Companies intermediate}

Try 1 Question(s) Test

Q23. What is the advantage of using static final or constant variables in Java ?

Core Java

Ans. Better Control - If the value is being used at multiple locations , that can be controlled better from single place. Any change would only require making single change.

Meaning , Aliasing and Better Readability - Sometimes its easy to read the value by its meaning or alias ( 0 as ZERO or 0 as NEUTRAL_VALUE ).

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve static final final variable variable constants}

Frequently asked.

Q24. When does the finally block gets executed ?

Core Java

Ans. A finally block of code always executes, whether or not an exception has occurred.The only time finally won't be called is if you call System.exit() or if the JVM crashes first.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve finally exception handling exceptions Asked in 4 Companies basic frequent}

Q25. Can you assign value to a static final type at runtime ?

Core Java

Ans. No

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve static final static final Asked in 1 Companies}

Very frequently asked. Favorite question in Walk in Drive of many Indian service companies.

Q26. What is a Final Variable ?

Core Java

Ans. Final variable is a variable constant that cannot be changed after initialization.

Sample Code for final variable

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve oops java final final variable basic interview question Asked in 12 Companies basic frequent}

Try 1 Question(s) Test

Very frequently asked. Favorite question in Walk in Drive of many Indian service companies.

Q27. What is a final method ?

Core Java

Ans. Its a method which cannot be overridden. Compiler throws an error if we try to override a method which has been declared final in the parent class.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java oops final final method Asked in 30 Companies basic frequent}

Try 1 Question(s) Test

Q28. What is a Final Method ?

Core Java

Ans. A Method that cannot be overriden in the sub class.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java oops java keywords final final method overriding basic interview question basic frequent}

Try 1 Question(s) Test

Very Frequently asked.Favorite question in Walk in drive for many Indian service companies.

Q29. What is a Final Class ?

Ans. A Class that cannot be sub classed.

Sample Code for final class

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java oops final final class java keyword basic interview question Asked in 3 Companies basic frequent}

Q30. Does Declaring an object "final" makes it immutable ?

Core Java

Ans. Only declaring variables as final makes them immutable. Making objects final means that the object handler cannot be used to target some other object but the object is still mutable.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java oops final immutable immutability immutable immutability object}

Search Interview Questions

Help us and Others Improve. Please let us know the questions asked in any of your previous interview.