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Core java - Interview Questions and Answers for 'Jpmorgan chase' - 5 question(s) found - Order By Newest | ||||
Very frequently asked in different variations. Frequently asked in Deloitte ( 2 feedback ) , HCL Tech ( 3 feedback ), TCS and Coginizant (CTS) | ||||
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Ans. If the Object value will not change, use String Class because a String object is immutable. If the Object value can change and will only be modified from a single thread, use StringBuilder because StringBuilder is unsynchronized(means faster). If the Object value may change, and can be modified by multiple threads, use a StringBuffer because StringBuffer is thread safe(synchronized). | ||||
Sample Code for String Sample Code for StringBuffer Sample Code for StringBuilder | ||||
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Like Discuss Correct / Improve  java   string class   string   stringbuilder   stringbuffer   String vs StringBuffer   String vs StringBuilder   String vs StringBuilder vs StringBuffer   StringBuffer vs stringBuilder Asked in 29 Companies basic   frequent | ||||
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Very frequently asked across all types of companies. | ||||
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Ans. Hashtable is synchronized whereas HashMap is not.HashMap allows null values whereas Hashtable doesnt allow null values. | ||||
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Like Discuss Correct / Improve  java   collections   hashmap   map   hashtable   hashmap vs hashtable Asked in 14 Companies basic   frequent | ||||
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Ans. We can make a class immutable by 1. Making all methods and variables as private. 2. Setting variables within constructor. Public Class ImmutableClass{ private int member; ImmutableClass(int var){ member=var; } } and then we can initialize the object of the class as ImmutableClass immutableObject = new ImmutableClass(5); Now all members being private , you cant change the state of the object. | ||||
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Like Discuss Correct / Improve  java   oops   immutable  immutability   immutable  immutability class   technical lead Asked in 5 Companies intermediate   frequent | ||||
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Very frequently asked in phone and walk in interviews. | ||||
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Ans. An interface without any method declaration is called as marker interface. there are 3 in-built interfaces in JVM i.e. serializable, clonable, remote | ||||
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Like Discuss Correct / Improve  java   oops   interfaces   marker interface   serializable   clonable Asked in 21 Companies intermediate   frequent | ||||
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Very frequently asked. Usually difference between String,StringBuffer and StringBuilder is asked in different variations. | ||||
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Ans. StringBuffer is synchronized whereas StringBuilder is not. | ||||
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Like Discuss Correct / Improve  java   string   stringbuffer   string class   stringbuilder   synchronized   basic interview question   infosys technologies Asked in 17 Companies basic   frequent | ||||
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