Interview Questions and Answers for 'T' | Search Interview Question

Interview Questions and Answers - Order By Newest

Q1141. Can there be a Thread without a Process ?

Core Java

Ans. No.

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Q1142. Can we have an inner class within Interface ?

Core Java

Ans. Yes, we can define an inner class within interface.Inside the interface, the inner class is implicitly public static.

So the following is legit in Java

public interface BuggyBreadInterface {
   void doSomething();

   public class BuggyBreadClass implements BuggyBreadInterface{
      void doSomething(){
         System.out.println("Do something");
      }
   }
}

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Q1143. Is it a valid identifier in Java ?

int 123Abc = 5;

Core Java

Ans. No, identifier in java cannot start with a numeral.

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Q1144. What is the difference between Collections.emptyList() and creating new instance of List using new ?

Core Java

Ans. But Collections.emptyList() returns an Immutable list whereas new arraylist() creates a mutable list.

Advantage of getting an empty list using Collections.emptyList is that it returns a singleton list which can be shared among many references and hence made immutable. This is good fit for situations where we would like to initialize a list to basic minimum empty to avoid null pointer exception.

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Frequently asked Design Pattern interview question.

Q1145. What is a prototype design pattern ?

Design

Ans. The prototype pattern is a creational design pattern. It is used when the type of objects to create is determined by a prototypical instance, which is cloned to produce new objects. Prototype is used when we need duplicate copies of objects.

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Q1146. Write a Test Case using Mock ?

Testing

Ans. http://javasearch.buggybread.com/CodeSnippets/searchCodeSamples.php?keyword=mock&category=code

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Very frequently asked.

Q1147. What is the use of synchronized keyword ?

Core Java

Ans. Synchronize is used to achieve mutual exclusion i.e at one time, the segment of the code, method that has been declared synchronized should be executed by single thread only and hence the lock needs to be retrieved before executing the segment and then released.

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Q1148. Write an SQL Statement to add a foreign key constraint in oracle ?

Database

Ans. ALTER TABLE <Table_Name> ADD CONSTRAINT <Constraint_Name> FOREIGN KEY (<Column_Name>) REFERENCES <Foreign_Table>(<Foreign_Column>);

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Q1149. How to Change Default Boot Kernel in Linux ?

Unix

Ans. https://www.redhat.com/archives/rhl-list/2005-April/msg04167.html

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Q1150. What is a Test Dependency Scope in Maven ?

Maven

Ans. This scope indicates that the dependency is not required for normal use of the application, and is only available for the test compilation and execution phases. This scope is not transitive.

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Q1151. What does the web status code 404,500 and 200 mean ?

Java EE

Ans. 404 means the resource is not found on the server.The resource might not be deployed correctly.

500 means internal server error which means that resource was located but then it resulted in some exception or error.

200 means Ok.

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Try 1 Question(s) Test

Q1152. If Project A is calling web service of project B and there are some changes in project B, Will Project A needs to be rebuilt ?

Maven

Ans. That depends if the interface for the resource in Project B gets changed. If only the internal implementation is changed, No change is required in Project A. Project A is not even required to be rebuilt.

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Q1153. What is Dirty read in Database Transactions ?

Database

Ans. A dirty read occurs when a transaction is allowed to read data from a row that has been modified by another running transaction but not yet committed.

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Q1154. Have you ever felt the need of keeping the constructor private ?

Design

Ans. Yes, When either we don't want an object to be created ( class having all static elements and hence not required ) or object to be created using a static method or static block. One such example could be a situation when we would like app to load objects at start up and we would like to restrict new object creation by any request.

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Usually asked with Questions related to Generics.

Q1155. What are Type Erasures in Java ?

Core Java

Ans. Type erasure applies to the use of generics. When generics are used, they're pre compiled into compile time checks and execution-time casts.

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Q1156. 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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Q1157. Watching a directory for changes. Monitoring a directory.

Core Java

Ans. http://www.logicbig.com/tutorials/core-java-tutorial/java-nio/java-watch-service/

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Q1158. How can one determine if JVM is 32-bit or 64-bit from Java Program ?

Core Java

Ans. There is a Java system property "sun.arch.data.model" that can tell if JVM is 32 bit of 64 bit

System.getProperty("sun.arch.data.model") can be used to get that property.

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Q1159. How can we find the memory usage of JVM from Java code?

Core Java

Ans. Using Runtime object.

Runtime runtime = Runtime.getRuntime();

runtime.totalMemory();
runtime.freeMemory();

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Q1160. How can we catch an exception thrown by another thread ?

Core Java

Ans. http://stackoverflow.com/a/6548203/2789764

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Q1161. Why calculations in float or Double sometimes gives unpredictable results ?

Core Java

Ans. Because the way float values are stored its not precise.

For example - 0.1 is actually stored as
0.1000000000000000055511151231257827021181583404541015625

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Q1162. What different level of logging you use while coding ?

Logging

Ans. I use trace for debugging purpose. Info for displaying some important info, thought its rare as we have enabled info logging in production. Warn in case something went wrong but we still resume the flow in spite of it or have take alternate flow as its expected sometimes. Error logging in case it was completely unexpected and mostly when it breaks the flow.

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Q1163. Explain Travelling SalesMan Problem ?

Algorithm

Ans. https://en.wikipedia.org/wiki/Travelling_salesman_problem

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Q1164. What is the use of @Before annotation ?

Junit

Ans. When executing tests it is common that multiple tests need similar objects to be created before they can run. @before specifies a method that provide that initialization for the set of Unit Tests.

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Q1165. What is Java NumberFormatException ?

Core Java

Ans. NumberFormatException is the exception that Java throws when we try to convert one data type to the Number data type but the value is not parsable to be a Number.

For example , the following code will result in the NumberFormatException

String string = "Buggy";
int strtoInt = Integer.parseInt(string);

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Q1166. Write a Java Program to check Armstrong Number ?

Core Java

Ans. http://www.programmingsimplified.com/java/source-code/java-program-armstrong-number

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Q1167. 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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Q1168. 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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Q1169. 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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Q1170. What is the use of return statement without any argument ?

Core Java

Ans. Such return is only expected in methods that returns void. the purpose of having return in such a method is to return the flow out of method and return to the place where it was called. Its actually used to prematurely return the control from the method.

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