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Core Java - Interview Questions and Answers for 'Hash code' - 6 question(s) found - Order By Newest

 Q1. Why String is popular HashMap key in Java?Core Java
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Ans. Since String is immutable, its hashcode is cached at the time of creation and it doesnt need to be calculated again. This makes it a great candidate for key in a Map and its processing is fast than other HashMap key objects. This is why String is mostly used Object as HashMap keys.

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   Like         Discuss         Correct / Improve     java   string class   string   immutable  immutability   hashmap   immutable  immutability   hashcode   hash code   advanced     Asked in 2 Companies      expert        frequent


 Q2. public class a {
   public static void main(String args[]){
      final String s1=""job"";
      final String s2=""seeker"";
      String s3=s1.concat(s2);
      String s4=""jobseeker"";
      System.out.println(s3==s4); // Output 1
      System.out.println(s3.hashCode()==s4.hashCode()); Output 2
   }
}

What will be the Output 1 and Output 2 ?
Core Java
Admin
info@buggybread.com
Ans. S3 and S4 are pointing to different memory location and hence Output 1 will be false.

Hash code is generated to be used as hash key in some of the collections in Java and is calculated using string characters and its length. As they both are same string literals, and hence their hashcode is same.Output 2 will be true.

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   Like         Discuss         Correct / Improve     java   string   hashcode   hash code   string comparison   string pool

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  Q3. What is the use of HashCode in objects ?Core Java
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Ans. Hashcode is used for bucketing in Hash implementations like HashMap, HashTable, HashSet etc.

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   Like         Discuss         Correct / Improve     java   string   hashcode   hash code   string comparison  hashtable     Asked in 17 Companies      basic        frequent


Very Frequently asked. Favorite question in walkins and telephonic interviews. Usually among first few questions. Asked in different variants. Must know for intermediate and expert professionals.Among Top 10 frequently asked questions.
  Q4. What is rule regarding overriding equals and hashCode method ?Core Java
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Ans. A Class must override the hashCode method if its overriding the equals method.

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   Like         Discuss         Correct / Improve     java   collections   hashcode  hash code   equals   collections     Asked in 44 Companies      intermediate        frequent

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 Q5. What is collision in hash collections ?Core Java
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Ans. Collision is the situation when two different elements have the same Hash Code.

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   Like         Discuss         Correct / Improve     java   collections   collision   hashcode  hash code   hash collections   ebay     Asked in 1 Companies      intermediate        frequent


 Q6. How are hash codes generated ?Data Structure2018-04-18 19:12:52

 This question was recently asked at 'Collabera'.This question is still unanswered. Can you please provide an answer.


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   Like         Discuss         Correct / Improve     hash codes  hashcode     Asked in 1 Companies




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