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| Core java - Interview Questions and Answers for 'Hsbc' - 6 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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| Frequently asked at Manhattan Associates ( Based on 2 feedback ) | ||||
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| Ans. Its an anonymous method without any declaration. Lambda Expression are useful to write shorthand Code and hence saves the effort of writing lengthy Code. It promotes Developer productivity, Better Readable and Reliable code. | ||||
 Sample Code for lambda | ||||
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| Discuss Correct / Improve java java8 lambda expression architecture Asked in 58 Companies expert frequent | ||||
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| Ans. OOPs or Object Oriented Programming is a Programming model which is organized around Objects instead of processes. Instead of a process calling series of processes, this model stresses on communication between objects. Objects that all self sustained, provide security by encapsulating it's members and providing abstracted interfaces over the functions it performs. OOP's facilitate the following features 1. Inheritance for Code Reuse 2. Abstraction for modularity, maintenance and agility 3. Encapsulation for security and protection 4. Polymorphism for flexibility and interfacing | ||||
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| Discuss Correct / Improve oops oops features Asked in 260 Companies basic frequent | ||||
| Basic and Very Frequently asked. | ||||
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| Ans. Polymorphism means the condition of occurring in several different forms. Polymorphism in Java is achieved in two manners 1. Static polymorphism is the polymorphic resolution identified at compile time and is achieved through function overloading whereas 2. Dynamic polymorphism is the polymorphic resolution identified at runtime and is achieved through method overriding. | ||||
| Sample Code for overloading Sample Code for overriding | ||||
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| Discuss Correct / Improve polymorphism object oriented programming (oops) oops concepts oops concepts Asked in 108 Companies Basic 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. Part of JVM which is used to load classes and interfaces. Bootstrap , Extension and System are the class loaders used by JVM. | ||||
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| Discuss Correct / Improve java class loaders classloaders jvm java memory management advanced Asked in 3 Companies | ||||
Which of the following class creates mutable objects ?
