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| Core java - Interview Questions and Answers for 'Nakisa' - 3 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 | ||||
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 Related Questions | ||||
 What is the difference between = and == in Java ? | ||||
| How is == operator different for objects and primitive types ? | ||||
| What will be the output of following code Integer x = 1; Integer y = 2; System.out.println(x == y); What if you change 1 to "1" and Integer to String? | ||||
| 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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| Related Questions | ||||
| Why Char array is preferred over String for storing password? | ||||
| How does making string as immutable helps with securing information ? How does String Pool pose a security threat ? | ||||
| How is string object immutable if we can concat a string to it ? | ||||
| How to implement an immutable class ? | ||||
| What is an immutable class ? | ||||
| What is an Immutable Object ? | ||||
| Does Declaring an object "final" makes it immutable ? | ||||
| Is String final in Java ? | ||||
| What are stateless objects ? How are they different from immutable objects ? Which of these two is thread safe ? | ||||
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| Ans. 1. Stack Segment - Contains primitives, Class / Interface names and references. 2. Heap Segment - Contains all created objects in runtime, objects only plus their object attributes (instance variables), Static variables are also stored in heap. 3. Code Segment - The segment where the actual compiled Java bytecodes resides when loaded | ||||
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| Discuss Correct / Improve java memory memory management stack memory heap memory code segment memory advanced Asked in 9 Companies expert frequent | ||||
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| Related Questions | ||||
| What are different ways to create String Object? Explain. | ||||
| Does garbage collection guarantee that a program will not run out of memory? | ||||
| Describe, in general, how java's garbage collector works ? | ||||
| Describe what happens when an object is created in Java ? | ||||
| What are various types of Class loaders used by JVM ? | ||||
| What are strong, soft, weak and phantom references in Java ? | ||||
| Why two types of memory - stack and heap are required by Java ? | ||||
| Should we override finalize method ? | ||||
| Which memory areas does instance and static variables use ? | ||||
| Can we call the garbage collector explicitly ? | ||||
