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| Core java - Interview Questions and Answers for 'Efi' - 7 question(s) found - Order By Newest | ||||
 Very frequently asked. Among first few questions in almost all interviews. Among Top 5 frequently asked questions. Frequently asked in Indian service companies (HCL,TCS,Infosys,Capgemini etc based on multiple feedback ) and Epam Systems | ||||
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| Ans. "equals" is the method of object class which is supposed to be overridden to check object equality, whereas "==" operator evaluate to see if the object handlers on the left and right are pointing to the same object in memory. x.equals(y) means the references x and y are holding objects that are equal. x==y means that the references x and y have same object. Sample code: String x = new String("str"); String y = new String("str"); System.out.println(x == y); // prints false System.out.println(x.equals(y)); // prints true | ||||
 Sample Code for equals | ||||
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 Discuss Correct / Improve  java string comparison string object class == equals object equality operator == vs equals equals vs ==  Asked in 294 Companies  basic  frequent | ||||
 Try 6 Question(s) Test | ||||
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| Ans. All exceptions must be a child of Throwable. If you want to write a checked exception that is automatically enforced by the Handle or Declare Rule, you need to extend the Exception class. You want to write a runtime exception, you need to extend the RuntimeException class. | ||||
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| Discuss Correct / Improve java exceptions exception handling user defined exceptions throwable architecture library development technical architect technical lead | ||||
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| Ans. With Collection classes , we cannot use primitive types. Moreover for any class using generic types, we cannot use primitive types. They add more functionality by means of additional methods. As their reference can be null , they offer consistent check for uninitialized state. They facilitate caching and reuse by means of constant Pools. | ||||
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| Discuss Correct / Improve wrapper classes benefits of wrapper classes over primitives | ||||
| Frequently asked in high end product companies. | ||||
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| Ans. https://www.geeksforgeeks.org/lru-cache-implementation/ | ||||
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| Discuss Correct / Improve cache LRU cache coding code Asked in 10 Companies intermediate | ||||
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| Ans. Abstraction, Encapsulation, Polymorphism , Composition and Inheritance | ||||
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| Discuss Correct / Improve core oops concepts Asked in 65 Companies basic frequent | ||||
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| Ans. Immutable objects are thread-safe so you will not have any synchronization issues.Immutable objects are good for Map keys and Set elements, since these typically do not change once created.Immutability makes it easier to write, use and reason about the code (class invariant is established once and then unchanged)Immutability makes it easier to parallelize your program as there are no conflicts among objects.The internal state of your program will be consistent even if you have exceptions.References to immutable objects can be cached as they are not going to change. | ||||
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| Discuss Correct / Improve immutable immutability classes benefits of immutable immutability classes Asked in 1 Companies | ||||
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| Ans. 1. JVM that makes it platform independent and facilitates portability. 2. Garbage Collector that protects from Memory Leaks. 3. Only usage of references and not pointer arithmetic and hence protects the application from memory issues like dangling pointers, memory leaks etc. 4. Support for OOPs that makes application development and maintenance easy. 5. Facilitates library development through use of interface / abstract classes. 6. Facilitates creation of scalable applications. 7. Huge repository of libraries and pool of people with java skill. | ||||
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| Discuss Correct / Improve benefits of java advantages of java basic frequent | ||||
Which of the following statement is not true ?
