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| Core java - Interview Questions and Answers for 'Prokarma' - 4 question(s) found - Order By Newest | ||||
 Advanced level question. Frequently asked in High end product companies. Frequently asked in Google , Cognizant and Deloitte ( Based on 2 feedback ) | ||||
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| Ans. 1. String Pool - When a string is created and if it exists in the pool, the reference of the existing string will be returned instead of creating a new object. If string is not immutable, changing the string with one reference will lead to the wrong value for the other references. Example - String str1 = "String1"; String str2 = "String1"; // It doesn't create a new String and rather reuses the string literal from pool // Now both str1 and str2 pointing to same string object in pool, changing str1 will change it for str2 too 2. To Cache its Hashcode - If string is not immutable, One can change its hashcode and hence it's not fit to be cached. 3. Security - String is widely used as parameter for many java classes, e.g. network connection, opening files, etc. Making it mutable might possess threats due to interception by the other code segment. | ||||
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 Discuss Correct / Improve  java oops string string class immutable immutability advanced  Asked in 39 Companies  expert  frequent | ||||
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| Ans. ConcurrentHashMap is a hashMap that allows concurrent modifications from multiple threads as there can be multiple locks on the same hashmap. | ||||
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| Discuss Correct / Improve java collections hashmap map concurrenthashmap concurrenthashmap concurrency general electric ge Asked in 32 Companies rare | ||||
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| Ans. This is the exception that is thrown when we try to modify the non concurrent collection class while iterating through it. | ||||
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| Discuss Correct / Improve java collections concurrentmodificationexception exception concurrency Asked in 14 Companies intermediate | ||||
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| Ans. No, results in exception. | ||||
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| Discuss Correct / Improve java collections treemap Asked in 6 Companies Basic frequent | ||||
Which of the following class creates mutable objects ?
