More than 3000 questions in repository. There are more than 900 unanswered questions. Click here and help us by providing the answer. Have a video suggestion. Click Correct / Improve and please let us know.
Ans. Abstract classes can have both abstract methods ( method declarations ) as well as concrete methods ( inherited to the derived classes ) whereas Interfaces can only have abstract methods ( method declarations ).
A class can extend single abstract class whereas it can implement multiple interfaces.
Help us improve. Please let us know the company, where you were asked this question :
Though the following code will compile fine but will result in ClassCastException during runtime.
Fruit fruit = new Apple();
Banana banana = Banana(fruit); // ClassCastException
This code will not give compile time error as Banana and Fruit are related as Banana either extends or implement Fruit, So downcasting is acceptable. With this code we assume that the Fruit handler will have the Apple object at that point, violating which the code will throw the exception.
This exception can be avoided by following code.
Fruit fruit = new Apple();
if(fruit instanceOf Banana){
Banana banana = Banana(fruit); // ClassCastException
}
Help us improve. Please let us know the company, where you were asked this question :
Ans. DocLint Provide a means to detect errors in Javadoc comments early in the development cycle and in a way that is easily linked back to the source code.
Help us improve. Please let us know the company, where you were asked this question :
Ans. Spring caching makes use of its intercepting capabilities to add caching to method calls. Therefore, the entire object is cached and reused. Hibernate, on the other hand, has more domain-specific knowledge of the Entity being cached and can handle the objects more appropriately.
Help us improve. Please let us know the company, where you were asked this question :
Ans. Http is connection less by default. header informs hosts to keep the connection alive so that the same connection can be reused for multiple communication.
Help us improve. Please let us know the company, where you were asked this question :
Ans. float is a native data type whereas Float is a class. A Float object will always take more memory than float variable as there are metadata overheads with the objects.
Help us improve. Please let us know the company, where you were asked this question :
Ans. Stack memory areas is used to hold method and local variables while objects are always allocated memory in the heap. The heap memory is shared between multiple threads whereas Stack memory isn't.
Help us improve. Please let us know the company, where you were asked this question :
Q1065. When are static and instance methods resolved ? During compile time or Runtime ?
Ans. Static methods are resolved during compile time and hence they cannot participate in runtime polymorphism. Instance methods are resolved during runtime.
Help us improve. Please let us know the company, where you were asked this question :
Ans. BlockingQueue is a Queue that supports operations that wait for the queue to become non-empty when retrieving and removing an element, and wait for space to become available in the queue when adding an element.
Help us improve. Please let us know the company, where you were asked this question :
Ans. Kafka is a distributed, partitioned, replicated commit log service. It provides the functionality of a messaging system through messages being written to logs.
Help us improve. Please let us know the company, where you were asked this question :
Q1072. Have you used Kafka in your project ? If Yes, for what ?
Ans. We were using Kafka as a replacement for JMS Message Queue for better throughput. We were just using a simple Java multi threaded client as order of message consumption didn't matter to us.
Help us improve. Please let us know the company, where you were asked this question :
Q1075. Which of the following can be marked static ?
a. Methods , Variables and Initialization Blocks.
b. Methods , Variables , Initialization Blocks and Outer Classes and nested Classes.
c. Methods , Variables , Initialization Blocks and Outer Classes.
d. Methods , Variables , Initialization Blocks and nested Classes
Methods , Variables , Initialization Blocks and Outer Classes and nested Classes.
Methods , Variables , Initialization Blocks and Outer Classes.
Methods , Variables , Initialization Blocks and nested Classes.
Which of the following cannot be marked static ?
Constructors , Classes ( Outer ) , Classes ( nested ), Interfaces , Local variables , Inner Class methods and instance variables.
Constructors , Classes ( Outer ) , Interfaces , Local variables , Class variables , Class Methods , Inner Class methods and instance variables.
Constructors , Classes ( Outer ) , Interfaces , Local variables , Inner Class methods and instance variables.
Constructors , Classes ( Outer ) , Classes (Nested), Interfaces , Local variables , Inner Class methods and instance variables.
Q1076. Which of the following cannot be marked static ?
a. Constructors , Classes ( Outer ) , Classes ( nested ), Interfaces , Local variables , Inner Class methods and instance variables. b. Constructors , Classes ( Outer ) , Interfaces , Local variables , Class variables , Class Methods , Inner Class methods and instance variables. c. Constructors , Classes ( Outer ) , Interfaces , Local variables , Inner Class methods and instance variables. d. Constructors , Classes ( Outer ) , Classes (Nested), Interfaces , Local variables , Inner Class methods and instance variables
Ans. Constructors , Classes ( Outer ) , Interfaces , Local variables , Inner Class methods and instance variables.
Help us improve. Please let us know the company, where you were asked this question :
More than 3000 questions in repository.
Discuss 
java stateless objects immutable immutability objects objects
Very Frequently asked. Have been asked in HCL Technologies very frequently ( based on 3 feedback ). Among first few questions in many interviews.
Asked in 82 Companies 
basic 
frequent
Try 2 Question(s) Test
Which of the following can throw ClassCastException ?
