Interview Questions and Answers for 'Streams' | Search Interview Question

Interview Questions and Answers for 'Streams' - 32 question(s) found - Order By Newest

Q1. Explain OOPs

or

Explain OOPs Principles

or

Explain OOPs Concepts

or

Explain OOPs features

or

Tell me something about OOPs

Core Java

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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Frequently asked to fresh graduates.

Q2. What is a Deadlock ?

Operating System

Ans. When two threads are waiting each other and cant precede the program is said to be deadlock.

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Q3. What is a stream and what are the types of Streams and classes of the Streams?

Core Java

Ans. A Stream is an abstraction that either produces or consumes information. There are two types of Streams :

Byte Streams: Provide a convenient means for handling input and output of bytes.

Character Streams: Provide a convenient means for handling input & output of characters.

Byte Streams classes: Are defined by using two abstract classes, namely InputStream and OutputStream.

Character Streams classes: Are defined by using two abstract classes, namely Reader and Writer.

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Usually asked to entry level software developers.

Q4. Write a program to swap two variables without using third

Core Java

Ans. public static void main(String[] args) {
   int num1 = 1;
   int num2 = 2;
   num1 = num1^num2;
   num2 = num1^num2;
   num1 = num1^num2;
   System.out.print("num1 = " + num1 +", num2 = "+num2);
}

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Q5. Name few IO Stream classes and interfaces ?

Core Java

Ans. http://www.buggybread.com/2015/01/java-stream-io-classes-and-interfaces.html

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Q6. What is System.in in Java ?

Core Java

Ans. It is an InputSream which is usually connected to the keyboard input of console program.

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Q7. Explain System.out.println ?

Core Java

Ans. System is a class within java.lang package that contains several useful class fields and methods. It cannot be instantiated and hence can use only statically.even in this case this has been used statically i.e with class name itself and without creating an instance.

out is the static reference of Printstream declared as following in the System Class -

public final static PrintStream out = null;

println is the method of PrintStream class.

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Q8. Tell something about BufferedWriter ? What are flush() and close() used for ?

Ans. BufferedWriter is temporary source for data storage.BufferedWriter is used to write character data to the file.Flush() is method available in B.W which ensures that all data items are written to file including last character.Close() is used to closes the character output stream.

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Q9. What is Scanner class used for ? when was it introduced in Java ?

Core Java

Ans. Scanner class introduced in Java 1.5 for reading Data Stream from the imput device. Previously we used to write code to read a input using DataInputStream. After reading the stream , we can convert into respective data type using in.next() as String ,in.nextInt() as integer, in.nextDouble() as Double etc

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Q10. What is the difference between the Reader/Writer class hierarchy and the InputStream/OutputStream class hierarchy?

Core Java

Ans. The Reader/Writer class hierarchy is character-oriented, and the InputStream/OutputStream class hierarchy is byte-oriented

Sample Code for InputStream

Sample Code for OutputStream

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Q11. Which is the abstract parent class of FileWriter ?

Core Java

Ans. OutputStreamWriter

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Q12. Which class is used to read streams of raw bytes from a file?

Core Java

Ans. FileInputStream

Sample Code for FileInputStream

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Q13. Which is the Parent class of FileInputStream ?

Core Java

Ans. InputStream

Sample Code for InputStream

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Q14. Which exceptions should be handled with the following code ?

FileOutputStream fileOutputStream = new FileOutputStream(new File("newFile.txt"));

Ans. FileNotFoundException

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Q15. Will this code compile fine ?

ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream(new File("newFile.txt")));

Core Java

Ans. Yes.

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Q16. Have you ever tried compressing data using Java ?

Core Java

Ans. Yes, we can use ZipInputStream class for compressing the FileInputstream object.

Sample Code for ZipInputStream

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Q17. How Spliterator in Java 8 different than iterator ?

Core Java

Ans. Though there are many differences the way internally they both iterates the collections and streams respectively, but the main difference in performance that is achieved by spliterator as it can iterate Streams in Parallel whereas iterator only iterates collections sequentially.

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Q18. Which is better in terms of performance - Iterator or Spliterator ?

Core Java

Ans. Spliterator has better performance potential than iterators but only if the potential is used. Spliterator can iterate streams in parallel as well as in sequence whereas iterator can only iterate in sequence.

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Q19. Difference between System.out.printf and System.out.println ?

Core Java

Ans. println prints an additional end of line whereas printf doesnt.

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Q20. What is Spring Security ?

Spring

Ans. Spring Security is a powerful and highly customizable authentication and access control framework. It is the de facto standard for securing Spring-based applications.

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Q21. What is the difference between the Reader/Writer java.io hierarchy and the Stream class hierarchy?

Core Java

Ans. The Reader/Writer hierarchy is character oriented, whereas the Stream class hierarchy is byte oriented.

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Q22. Write a class / program that takes few numbers from the input and then output the average ?

Core Java

Ans. public class Class{
   public static void main(String[] args){
      List<Integer> collector = new ArrayList();

      Scanner scanner = new Scanner(System.in);
      int x = scanner.nextInt();
      while(x != 0){
         collector.add(x);
         x = scanner.nextInt();
      }
      System.out.println(collector.stream().collect(Collectors.averagingInt(p->((Integer)p))));
   }
}

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Q23. What is a gobbler class ?

Core Java

Ans. A gobbler class take care of reading from a stream and optionally write out to another stream. Allows for non blocking reads when invoking a process through Runtime.exec(). Moreover the user can specify a callback that is called whenever anything is read from the stream.

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Q24. What is a shard in Kinesis stream ?

Amazon Web Services (AWS)

Ans. A shard is a uniquely identified group of data records in a stream or we can say that Shard is a partition in Kinesis stream. A shard supports a fixed bandwidth i.e fixed number of messages per second. The total capacity of the stream is the sum of the capacities of its shards. If the data rate changes, we can allocate / deallocate more shards to accommodate that.

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Q25. What is the relationship between shard and partition key in kinesis stream ?

Amazon Web Services (AWS)

Ans. A partition key is used to group data by shard within a stream. A partition key identifies which shard the message belong to.

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Q26. What is the difference between stream and parallel stream ?

Core Java

Ans. streams are used for sequential processing of data and parallel streams are used for parallel processing of data (only if the underlying processor is multicore).

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Q27. How can i split a linked list in two parts in java 8?

Core Java

Ans. This can be done using a Spliterator.

LinkedList list = Arrays.asList("names","numbs","birds","animals");
Spliterator split1 = list.Spliterator();
Spliterator split2 = split1.Spliterator();

Now, the LinkedList is split into split1 and split2.
use split2 first then split1 to check the output.

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Q28. What are we doing here

list.stream().collect(Collectors.groupingBy(ClassA::getElement1,
Collectors.averagingDouble(ClassA::getelement2)));

Core Java

Ans. We are averaging elements of a collection by element1 grouped by element1

* list is the reference of collection
* element1 is the member element returned by getElement1 method of ClassA
* element2 is the member element returned by getElement2 method of ClassA

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Q29. What will the following code return

list.stream().collect(Collectors.groupingBy(ClassA::getElement1,
Collectors.averagingDouble(ClassA::getElement2)));

Core Java

Ans. Map<DataType1,DataType2> where DataType1 is the data type of element1 ( returned by getelement1 method ) and DataType2 is the data type of element2 ( returned by getElement2 method )

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Q30. How does encoding affect using Reader / writer classes or Stream classes in Java ?

Core Java

Ans. Which group of bytes represent which character is defined by character encoding. So when reading character by character from a stream of bytes using Reader, specifying character encoding becomes significant as the same group of bytes can represent different character in different character encoding(Eg UTF-8 and UTF-16 etc.)

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