Core Java - Interview Questions and Answers for 'Classe' | Search Interview Question

Interview Questions and Answers - Order By Newest

Q61. Is immutability an advantage with Wrapper classes over primitive types ?

Ans. There is no concept of de referencing with primitive types and hence they are implicitly immutable. Having wrapper classes as mutable offers disadvantages compared to primitive types. Wrapper classes being immutable offer similar advantage as primitive types.It actually overshadows the disadvantage wrapper class could have if they are immutable.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve immutable immutability classes wrapper classes}

Q62. Which immutable classes have you worked with ? Can you name some immutable Collections ? How to make an immutable collection ?

Core Java

Ans. string and wrapper class objects

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve immutability immutable immutability classes immutable immutability collections Asked in 3 Companies}

Q63. What are the benefits of immutability or Immutable classes ?

Core Java

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.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve immutable immutability classes benefits of immutable immutability classes Asked in 1 Companies}

Q64. Which are the thread safe / synchronized / concurrent classes in java collections ?

Core Java

Ans. Stack
Properties
Vector
BlockingQueue
ConcurrentMap
ConcurrentNavigableMap

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve collections concurrent classes}

Q65. Can we have interface as a replacement for utility class ?

Core Java

Ans. Yes, With Java 8 we can use Interfaces as collection of utility methods through the use of default methods.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve java 8 interfaces utility class utility classes}

Q66. Why Concurrent Collection Classes are fail-fast in Java ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve concurrent collection classes fail fast fail-fast collections collection classes expert}

Q67. difference between ArrayList and array ?

Core Java

Ans. ArrayList is a variable length collection class whereas arrays are fixed length primitive structure.

We can use generics with arraylist but not with arrays.

We can store primitive data types within arrays but can't with ArrayList. In ArrayList that needs to be converted to Wrapper objects.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve arraylist arrays collection classes collections basic frequent}

Q68. What is the different between collection and Stream Api ?

Core Java

Ans. data under collection are actually stored in memory so that they can be retrieved when needed whereas data in streams are not stored and hence we need to construct it again when needed.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve collection classes stream api collection vs stream Asked in 1 Companies}