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Q841. In this url

http://javasearch.buggybread.com/InterviewQuestions/questionSearch.php?searchOption=label&keyword=url

What is protocol , domain , path and query param ?

Ans. the web URI starts with the protocol which is http in this case, javasearch.buggybread.com is the domain in this case which is a subdomain of buggybread.com, /InterviewQuestions is the path, questionSearch.php is the resource, searchOption and keyword are query params.

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Q842. What is the character limit of url and doesn it apply to GET and POST Requests ?

Ans. Its 2048 and Yes it applies to get request but not POST. As in Get Request , elements are passed as part of the url, this limit applies to Get requests.

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Q843. Write code for Binary tree traversal ?

Ans. http://javabeat.net/binary-search-tree-traversal-java/

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Q844. Can there be a Thread without a Process ?

Ans. No.

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Q845. Can we have an inner class within Interface ?

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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Q846. Is it a valid identifier in Java ?

int 123Abc = 5;

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

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Q847. What is the difference between Collections.emptyList() and creating new instance of List using new ?

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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Very frequently asked.

Q848. What is the use of synchronized keyword ?

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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Q849. What does the web status code 404,500 and 200 mean ?

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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Usually asked with Questions related to Generics.

Q850. What are Type Erasures in 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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Q851. Have you ever tried compressing data using Java ?

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

Sample Code for ZipInputStream

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Q852. Watching a directory for changes. Monitoring a directory.

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

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Q853. How can one determine if JVM is 32-bit or 64-bit from Java Program ?

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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Q854. Is ++ or -- operation thread safe in Java ?

Ans. No

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Q855. How can we find the memory usage of JVM from Java code?

Ans. Using Runtime object.

Runtime runtime = Runtime.getRuntime();

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

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Q856. How can we catch an exception thrown by another thread ?

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

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Q857. How can you check if a String is a 10 digit number by using regular expression ?

Ans. We can use \d{10} as the expression to check that

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Q858. How to check the version of Java through Java program itself ?

Ans. We can use System.getProperty("java.version");

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Q859. how can we get the System Environment variables from within Java program ?

Ans. We can use System.getenv for getting the environment variables. For ex - System.getenv("JAVA_HOME")

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Q860. Why calculations in float or Double sometimes gives unpredictable results ?

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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Q861. If we parse any string to get another data type and the String doesn't abide by the type of data it should have hold, what would happen ?

Ans. It will throw Parse Exception.

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Q862. Can we modify the variables defined in an interface ?

Ans. No, member variables of a interface are final by default. The final ensures the value assigned to the interface variable is a true constant that cannot be re assigned by program code.

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Q863. Can we declare a member element as abstract ?

Ans. No, only methods can be declared abstract.

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Q864. What are the primitive data types in Java ?

Ans. boolean byte char double float int long short void

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Q865. Have you ever heard of InstanceAlreadyExistsException ?

Ans. This exception usually occur if we try to register the bean with name already present in the registry or repository. Usually this happens when multiple tests are executed at once in single container.

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Q866. What is Java NumberFormatException ?

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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Q867. Write a Java Program to check Armstrong Number ?

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

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Q868. How Spliterator in Java 8 different than iterator ?

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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Q869. Which is better in terms of performance - Iterator or Spliterator ?

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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Q870. Difference between System.out.printf and System.out.println ?

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

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