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

Interview Questions and Answers - Order By Newest

Q521. Will static block for Test Class execute in the following code ?

class Test
{
static
{
System.out.println("Executing Static Block.");
}
public final int param=20;

public int getParam(){
return param;
}
}

public class Demo
{
public static void main(String[] args)
{
System.out.println(new Test().param);
}
}

Ans. Yes.

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

_{Like Discuss Correct / Improve java static static block final variable yes no}

Try 1 Question(s) Test

Q522. Write a Program to add 1-100, 101-200, 201-300 in different threads and then sum the numbers ?

Core Java

Ans. public class TotalUsingThreads extends Thread{

   private static List<TotalUsingThreads> collector = new ArrayList<TotalUsingThreads>();

   private int startFrom = 0;

   private Integer threadTotal = null;

   Test(int startFrom){
      this.startFrom = startFrom;
   }


   public static void main(String[] args) throws InterruptedException{
      int totalSum = 0;

      // Create all the threads and set the count starting point for all of them
      for(int count=0;count<10;count++){
         TotalUsingThreads newThread = new TotalUsingThreads(count*100);
         newThread.start();
         collector.add(newThread);
      }

      boolean allCollected = false;


      // Make sure that all thread totals are collected and all threads have completed their tasks
      while(!allCollected){
         for(int count=0;count<10;count++){
            if(collector.get(count).threadTotal == null){
               Thread.sleep(100);
               break;
            }
         }
         allCollected = true;
      }

      // sum totals of all threads
      for(int count=0;count<10;count++){
         totalSum += collector.get(count).threadTotal;
      }

      System.out.println(totalSum);


   }

   public void run(){
      threadTotal = 0;
      for(int count=startFrom;count<startFrom+100;count++){
       threadTotal += count;
      }
   }
}

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

_{Like Discuss Correct / Improve coding code threads multithreading Asked in 1 Companies}

Q523. If you have access to a function that returns a random integer from one to five, write another function which returns a random integer from one to seven.

Core Java

Ans. We can do that by pulling binary representation using 3 bits ( random(2) ).

getRandom7() {
   String binaryStr = String.valuesOf(random(2))+String.valuesOf(random(2))+String.valuesOf(random(2));
   binaryInt = Integer.valueOf(binaryStr);
   int sumValue=0;
   int multiple = 1;
   while(binaryInt > 0){
      binaryDigit = binaryInt%10;
      binaryInt = binaryInt /10;
      sumValue = sumValue + (binaryDigit * multiple);
      multiple = multiple * 2;
   }
}

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

_{Like Discuss Correct / Improve java tricky question interesting questions google interview questions random}

Q524. Write a method to convert binary to a number ?

Core Java

Ans.
convert(int binaryInt) {
   int sumValue=0;
   int multiple = 1;
   while(binaryInt > 0){
      binaryDigit = binaryInt%10;
      binaryInt = binaryInt /10;
      sumValue = sumValue + (binaryDigit * multiple);
      multiple = multiple * 2;
   }
   return sumValue;
}

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

_{Like Discuss Correct / Improve java binary interesting question coding}

Q525. What will be the output of the following code ?

String s1 = "Buggy Bread";
String s2 = "Buggy Bread";
if(s1 == s2)
System.out.println("equal 1");
String n1 = new String("Buggy Bread");
String n2 = new String("Buggy Bread");
if(n1 == n2)
System.out.println("equal 2");

Core Java

Ans. equal 1

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

_{Like Discuss Correct / Improve java string class string string pool code coding basic frequent}

Q526. What is Java bytecode ?

Ans. Java bytecode is the instruction set of the Java virtual machine. Each bytecode is composed by one, or two bytes that represent the instruction, along with zero or more bytes for passing parameters.

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

_{Like Discuss Correct / Improve java jvm interpreter platform independent Asked in 1 Companies}

Q527. Is JVM a overhead ?

Ans. Yes and No. JVM is an extra layer that translates Byte Code into Machine Code. So Comparing to languages like C, Java provides an additional layer of translating the Source Code.

C++ Compiler - Source Code --> Machine Code
Java Compiler - Source Code --> Byte Code , JVM - Byte Code --> Machine Code

Though it looks like an overhead but this additional translation allows Java to run Apps on all platforms as JVM provides the translation to the Machine code as per the underlying Operating System.

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

_{Like Discuss Correct / Improve java jvm interpreter platform independent yes-no advanced architecture}

Q528. Can we use Ordered Set for performing Binary Search ?

Ans. We need to access values on the basis of an index in Binary search which is not possible with Sets.

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

_{Like Discuss Correct / Improve java sets set collections binary search}

Q529. What is Byte Code ? Why Java's intermediary Code is called Byte Code ?

Ans. Bytecode is a highly optimized set of instructions designed to be executed by the Java run-time system. Its called Byte Code because each instruction is of 1-2 bytes.

Sample instructions in Byte Code -

1: istore_1
2: iload_1
3: sipush 1000
6: if_icmpge 44
9: iconst_2
10: istore_2

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

_{Like Discuss Correct / Improve java jvm interpreter platform independent byte code}

Q530. Difference between PATH and CLASSPATH ?

Operating System

Ans. PATH is the variable that holds the directories for the OS to look for executables. CLASSPATH is the variable that holds the directories for JVM to look for .class files ( Byte Code ).

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

_{Like Discuss Correct / Improve java path classpath byte code jvm basic interview question Asked in 3 Companies intermediate rare}

Q531. Name few access and non access Class Modifiers ?

Ans. private , public and protected are access modifiers.

final and abstract are non access modifiers.

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

_{Like Discuss Correct / Improve java access specifiers access modifiers modifiers access control}

Q532. Which Java collection class can be used to maintain the entries in the order in which they were last accessed?

Ans. LinkedHashMap

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

_{Like Discuss Correct / Improve java collections hashmap linkedhashmap}

Q533. Is it legal to initialize List like this ?

LinkedList l=new LinkedList();

Ans. No, Generic parameters cannot be primitives.

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

_{Like Discuss Correct / Improve java collections list linkedlist generics yes-no}

Q534. What will be the output of following code ?

public static void main(String[] args)
{
int x = 10;
int y;
if (x < 100) y = x / 0;
if (x >= 100) y = x * 0;
System.out.println("The value of y is: " + y);
}

Ans. The code will not compile raising an error that the local variable y might not have been initialized. Unlike member variables, local variables are not automatically initialized to the default values for their declared type.

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

_{Like Discuss Correct / Improve java code default value}

Q535. Which markup languages can be used in restful web services ?

Rest

Ans. XML and JSON ( Javascript Object Notation ).

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

_{Like Discuss Correct / Improve java web services rest java j2ee xml json architecture basic frequent}

Q536. what will be the output of this code ?

public static void main(String[] args){
   StringBuffer s1=new StringBuffer("Buggy");
   test(s1);
   System.out.println(s1);
}

private static void test(StringBuffer s){
   s.append("Bread");
}

Core Java

Ans. BuggyBread

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

_{Like Discuss Correct / Improve java code coding stringbuffer string method calling pass by reference}

Q537. what will be the output of this code ?

public static void main(String[] args)    {
   String s1=new String("Buggy");
   test(s1);
   System.out.println(s1);
}

private static void test(StringBuffer s){
   s.append("Bread");
}

Core Java

Ans. Buggy

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

_{Like Discuss Correct / Improve java code coding stringbuffer string method calling pass by reference}

Q538. what will be the output of this code ?

public static void main(String[] args)    {
   StringBuffer s1=new StringBuffer("Buggy");
   test(s1);
   System.out.println(s1);
}

private static void test(StringBuffer s){
   s=new StringBuffer("Bread");
}

Core Java

Ans. Buggy

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

_{Like Discuss Correct / Improve java code coding stringbuffer string method calling pass by reference}

Q539. what will be the output ?

class Animal {
public void eat() throws Exception {
}
}

class Dog2 extends Animal {
public void eat(){}
public static void main(){
Animal an = new Dog2();
an.eat();
}
}

Core Java

Ans. Compile Time Error: Unhandled exception type Exception

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

_{Like Discuss Correct / Improve java code coding overridding late binding exception handling abstract class abstract methods}

Q540. What are advantages of using Servlets over CGI ?

Java EE

Ans. Better Performance as Servlets doesn't require a separate process for a single request.

Servlets are platform independent as they are written in Java.

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

_{Like Discuss Correct / Improve java j2ee servlets servelets cgi}

Q541. What is the use of HTTPSession in relation to http protocol ?

Java EE

Ans. http protocol on its own is stateless. So it helps in identifying the relationship between multiple stateless request as they come from a single source.

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

_{Like Discuss Correct / Improve j2ee servlets web application session httpsession architecture Asked in 1 Companies}

Q542. Why using cookie to store session info is a better idea than just using session info in the request ?

Java EE

Ans. Session info in the request can be intercepted and hence a vulnerability. Cookie can be read and write by respective domain only and make sure that right session information is being passed by the client.

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

_{Like Discuss Correct / Improve j2ee servlets session session management web applications cookies httpsession architecture}

Q543. http protocol is by default ... ?

Java EE

Ans. stateless

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

_{Like Discuss Correct / Improve j2ee servlets session session management web applications cookies httpsession architecture}

Q544. Can finally block throw an exception ?

Core Java

Ans. Yes. Methods invoked from within a finally block can throw an exception. Failure to catch and handle such exceptions results in the abrupt termination of the entire try block.

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

_{Like Discuss Correct / Improve java exceptions exception handling finally yes-no}

Q545. Which of the following is a canonical path ?

1. C:\directory\..\directory\file.txt
2. C:\directory\subDirectory1\directory\file.txt
3. \directory\file.txt

Ans. 2nd

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

_{Like Discuss Correct / Improve java io file fileio}

Q546. What will the following code print when executed on Windows ?

public static void main(String[] args){
String parent = null;
File file = new File("/file.txt");
System.out.println(file.getPath());
System.out.println(file.getAbsolutePath());
try {
System.out.println(file.getCanonicalPath());
} catch (IOException e) {
e.printStackTrace();
}
}

Core Java

Ans. file.txtC:file.txtC:file.txt

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

_{Like Discuss Correct / Improve java io file fileio coding code file handling}

Q547. What will be the output of following code ?

public static void main(String[] args){
String child = null;
File file = new File("/folder", child);
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}

Core Java

Ans. NullPointerException at line:File file = new File("/folder", child);

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

_{Like Discuss Correct / Improve java io file fileio coding code file handling}

Q548. What will be the output of following code, assuming that currently we are in c:Project ?

public static void main(String[] args){
String child = null;
File file = new File("../file.txt");
System.out.println(file.getPath());
System.out.println(file.getAbsolutePath());
try {
System.out.println(file.getCanonicalPath());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

Core Java

Ans. ..file.txt
C:WorkspaceProject..file.txt
C:Workspacefile.txt

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

_{Like Discuss Correct / Improve java io file fileio coding code file handling}

Q549. Which is the abstract parent class of FileWriter ?

Core Java

Ans. OutputStreamWriter

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

_{Like Discuss Correct / Improve java io file fileio filewriter outputstreamwriter file handling}

Q550. Which class is used to read streams of characters from a file?

Core Java

Ans. FileReader

Sample Code for FileReader

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

_{Like Discuss Correct / Improve java io file fileio filereader file handling}

Search Interview Questions

Help us and Others Improve. Please let us know the questions asked in any of your previous interview.