Interview Questions and Answers for 'Code' | Search Interview Question

Interview Questions and Answers for 'Code' - 166 question(s) found - Order By Rating

Q1. Do you ever merge changes from one feature branch to another ? Why ?

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Q2. What is the use of defining equals , compareTo and hashcode methods in a class ? Where are they used ?

Core Java

Ans. equals, compareTo and hashcode are of use when the objects are used within collections.

Equals helps with collections that helps maintaining only unique objects ( like Set )

compare and compareTo helps with collections that helps maintaining objects in order ( TreeSet, TreeMap etc )

hascode helps with collections that facilitates hash searching ( like hashSet, hashMap etc )

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Q3. What are the scenarios you consider in code reviews

General

Ans. https://www.evoketechnologies.com/blog/code-review-checklist-perform-effective-code-reviews/

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Q4. Give an example of a time when you recommended code changes in a code review that simplified the code ?

Code Review

Ans. If there is a situation to remove duplicates values from an arrayList. Developer implemented using legacy for-loop where I suggested to use Linked hash set to remove duplicates from the list.

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Q5. Difference between equals and hashcode in java ?

Core Java

Ans. "equals" is the method of object class which is supposed to be overridden to check object equality. x.equals(y) means the references x and y are holding objects that are equal with the equality defined by the definition of equals method.

Hashcode is used for bucketing in Hash implementations like HashMap, HashTable, HashSet etc. The value received from hashcode() is used as bucket number for storing elements. This bucket number is the address of the element inside the set/map. when you do contains() then it will take the hashcode of the element, then look for the bucket where hashcode points to and if more than 1 element is found in the same bucket (multiple objects can have the same hashcode) then it uses the equals() method to evaluate if object are equal, and then decide if contain() is true or false, or decide if element could be added in the set or not.

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Q6. If you override hashcode to always return true, how a hash based collection will behave?

Core Java

Ans. At that bucket, it will form a linked list depending on what equals method evaluates for that object.

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Q7. in the following class:
class A {
void methoda(Object o) {
Sysout("Object");
}

void methoda(String s) {
Sysout("String");
}

public static void main(String []args) {
A a = new A();
a.methoda(null);
}
}

what will be printed?

Core Java

Ans. String

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Q8. Do you think it's a good practice to perform releases from a branch and then merge code to the master ?

SCM

Ans. We have followed this practice in one of the project. The only downside we felt was the need to merge the new snapshot version to master after the release.

The Benefit is that it's easy to just ignore the branch if complete rollback happens and hence master remains in sync with production.

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Q9. How do you branch your code within SCM ?

SCM

Ans. We keep a Working Branch , Release Branch and Master.

Working Branch is what we work on. We release from the release branch.

So the flow for merge is

Work Branch -> Release Branch -> Master

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Q10. Which memory segment holds the byte code ?

Core Java

Ans. Code Segment

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Q11. What is meant by "unreachable code" ? Can you write a code segment explaining this ?

Core Java

Ans. Unreachable code is a code segment that can never be executed in any case. For example -

int x = 5;
return;
System.out.println(x);

In this code , 2nd line will return the control out of the method and hence 3rd line will never get executed and hence is unreachable code. This will be caught at compile time only.

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Q12. Does Java generate .class file for interfaces ?

Core Java

Ans. Yes

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Q13. Write code to create a folder if it doesn't exist.

Core Java

Ans. File folder = new File(path);

if(!folder.exists()){
try {
folder.mkdir();

} catch (Exception e) {}
}

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Q14. How to calculate string length without using inbuilt function

Core Java

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Q15. How many bytes a character takes with UTF-8 encoding ?

Encoding

Ans. it takes 1 to 4 bytes

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Q16. Given a String with letters , numbers and special characters , extract Tokens from it. The rules for Token extraction are ac follows

1. Should for token of all characters till a number or special character is found
2. Should form token of all numbers till a character or special character is found
3. Special character in itself is a token
4. Ignore white spaces

For example - Bob Said "He is here"

should result in

Bob A
Said A
" S
He A
is A
here A
" S

where a is specifying alphabet and S as special character

Design

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Q17. Design a Program to clone an object and all it's children.

Design

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Q18. Find Intersection/union between two arrays.

Core Java

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Q19. How are hash codes generated ?

Data Structure

Ans. Use hashCode() which returns an integer value, generated by a hashing algorithm

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Q20. Write a Program to find number of lines , words and characters in a File.

Core Java

Ans. import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class FileUtility {

public static void main(String[] args) {
System.out.println(printFile("/home/userme/notes"));
}

private static int printFile(String filePath) {
int wordCount = 0;
try (BufferedReader br = new BufferedReader(new FileReader(filePath))) {
String line = null;
String[] wordsArray = null;

while ((line = br.readLine()) != null) {
wordsArray = line.split(" ");
wordCount = wordsArray.length;
}
} catch (IOException e) {
e.printStackTrace();
}
return wordCount;

}
}

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Q21. In the Following code which foo will get called.

foo(Integer i){
}

foo(String s){
}

public static void main(){
passing foo(null);
}

Core Java

Ans. ambiguity error

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Q22. Find different combination of given String and trace the output

Core Java

Ans. private void permutation(String prefix, String sufix)
{
int ln = sufix.length();
if(ln == 0) {
System.out.println(prefix);
} else {
IntStream.range(0, ln).forEach(i->permutation(prefix sufix.charAt(i), sufix.substring(0,i) sufix.substring(i 1, ln)));
}
}

call:permutation("", "abcdef");

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Q23. Write an efficient program for printing k largest elements in an array. Elements in array can be in any order.

Data Structure

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Q24. Suppose we have a string "Java is object oriented language" and we have to reverse every alternate word in string. How would we do that using Java program.

Core Java

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Q25. If a team member send you the code for review which you don't agree to but is just slightly off , Would you approve it or reject it ?

General

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Q26. Write a Program to check if the entered number is a Duck Number ( Number having 0 in it ) ?

Core Java

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Q27. What will be the output of following code

class TestMain {
public static void main(String[] args) {
String s1 = "ravi";
String s2 = new String("ravi");
Integer i = 10;
Integer a1 = new Integer("10");
System.out.println(s1 == s1);
System.out.println(i == a1);
}
}

Core Java

Ans. false
false

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Q28. Write code to find second largest number in an array of integers.

Core Java

Ans. int arr[]={1,3,5,6,4,8,9,2,10};
Arrays.sort();
System.out.println(arr[arr.length-1]);

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Q29. Write a Program to find age by birth date ?

Core Java

Ans. LocalDate today = LocalDate.now();
LocalDate birthday = LocalDate.of(1960, Month.JANUARY, 1);
Period p = Period.between(birthday, today); //Now access the values as below
System.out.println(period.getDays());
System.out.println(period.getMonths());
System.out.println(period.getYears());

Sample Code for LocalDate

Sample Code for Period

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Q30. How to calculate lcm of two numbers ?

Core Java

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