Interview Questions and Answers for 'Java' | Search Interview Question - javasearch.buggybread.com

Javasearch.buggybread.com

Search Interview Questions

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.

Submit Question

Interview Questions and Answers - Order By Newest

next 30

Q1461. How is it possible to use concat on string objects in Java, based on the fact that string is immutable?

Ans. It's possible because internally java first reserves the memory for the new concatenated string and then copy that over. So after concatenation, there are 2 strings in memory, the original one and the concatenated one and then the reference is moved to the concatenated string.

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

_{Like Discuss Correct / Improve}

Q1462. Difference between static and dynamic memory allocation ?

^{This question is still unanswered. Can you please provide an answer.}

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

_{Like Discuss Correct / Improve}

Q1463. Why Arrays are considered as data structures whereas ArrayList isn't ?

^{This question is still unanswered. Can you please provide an answer.}

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

_{Like Discuss Correct / Improve}

Q1464. Are Arrays a data structure or a collection class ?

^{This question is still unanswered. Can you please provide an answer.}

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

_{Like Discuss Correct / Improve}

Q1465. Which Java version supports Interface Default methods ?

Ans. Java 1.8 or Java 8

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

_{Like Discuss Correct / Improve default methods interface default methods java 8 java 8 features}

Q1466. Tell something about Sleep method.

^{This question was recently asked at 'IBM'.This question is still unanswered. Can you please provide an answer.}

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

_{Like Discuss Correct / Improve Thread sleep multithreading Asked in 1 Companies Basic}

Q1467. Diff between Runtime.getRunTime().gc() and System.gc()

^{This question was recently asked at 'CIGNEX Datamatics'.This question is still unanswered. Can you please provide an answer.}

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

_{Like Discuss Correct / Improve Asked in 1 Companies}

Q1468. How to run jar file using command prompt

^{This question was recently asked at 'CIGNEX Datamatics'.This question is still unanswered. Can you please provide an answer.}

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

_{Like Discuss Correct / Improve jar running jar using command line cron entry setting java app as cron Asked in 1 Companies}

Q1469. Can we call a static method using reference currently pointing to null.

Ans. yes, we can.
exa: public class Java{
public static void main(String... args) {
JAva j= null;
j.greeting(); // call with null reference
}
public static void greeting() {
System.out.println("Hello World");
}
} // output: Hello World

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

_{Like Discuss Correct / Improve static methods static Asked in 1 Companies}

Q1470. Which memory segment holds the byte code ?

Ans. Code Segment

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

_{Like Discuss Correct / Improve Memory Management Code Memory Segment Code Segment Memory Code Segment}

Q1471. Is this array declaration correct ? If not , Why ?

String[] strArray = new String[];

Ans. No, We haven't specified the size of array to be initialized.

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

_{Like Discuss Correct / Improve arrays array initialization}

Q1472. Is this array initialization correct ? If Yes, What will be the size of array ?

String[] strArray = new String[]{"Buggy","Bread"};

Ans. Yes, size of the array will be 2.

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

_{Like Discuss Correct / Improve arrays array initialization}

Q1473. Is this array initialization correct ? If Yes, What will be the size of array ?

String[] strArray = new String[3]{"Buggy","Bread"};

Ans. No. It will result in error saying "Cannot define dimension expressions when an array initializer is provided"

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

_{Like Discuss Correct / Improve arrays array initialization}

Q1474. Is this code valid

String[] strArray = new String[2];
strArray.length = 5;

Ans. It will give compile time error saying "The final field array.length cannot be assigned"

Arrays once initialized cannot be resized.

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

_{Like Discuss Correct / Improve arrays array initialization}

Q1475. What is the problem with this code

String[] strArray = new String[2];
strArray[0] = 5;

Ans. We are trying to add an integer element to an array of String. Will give compile time error.

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

_{Like Discuss Correct / Improve arrays}

Q1476. Will this give compile time error ?

Object[] strArray = new String[2];
strArray[0] = 5;

Ans. No. But It will throw ArrayStoreException at runtime.

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

_{Like Discuss Correct / Improve ArrayStoreException arrays}

Q1477. What is TypeCasting ?

Ans. Assigning a value of one type to a variable of another type is known as Type Casting.

Example :

int x = 10;
byte y = (byte)x;

In Java, type casting is classified into two types, Widening Casting(Implicit) widening-type-conversion and Narrowing Casting (Explicitly done) narrowing-type-conversion.

Widening or Automatic type converion - Automatic Type casting take place when,the two types are compatible and the target type is larger than the source type

Example :

public class Test {
public static void main(String[] args) {
int i = 100;
long l = i; //no explicit type casting required
float f = l;//no explicit type casting required
System.out.println("Int value " i);
System.out.println("Long value " l);
System.out.println("Float value " f);
}
}

Narrowing or Explicit type conversion - When you are assigning a larger type value to a variable of smaller type, then you need to perform explicit type casting.

Example :

public class Test{
public static void main(String[] args) {
double d = 100.04;
long l = (long)d; //explicit type casting required
int i = (int)l;//explicit type casting required
System.out.println("Double value " d);
System.out.println("Long value " l);
System.out.println("Int value " i);
}
}

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

_{Like Discuss Correct / Improve typecasting type casting Asked in 23 Companies}

Q1478. What is the biggest Design problem in Java ?

^{This question is still unanswered. Can you please provide an answer.}

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

_{Like Discuss Correct / Improve}

Q1479. Write a java program to find the maximum profit in day trading

^{This question was recently asked at 'Capital One'.This question is still unanswered. Can you please provide an answer.}

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

_{Like Discuss Correct / Improve Asked in 1 Companies}

Q1480. What are basic functions of OOPS ?

^{This question was recently asked at 'Zillious'.This question is still unanswered. Can you please provide an answer.}

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

_{Like Discuss Correct / Improve Asked in 1 Companies}

Q1481. Where to use interface and abstract class ?

^{This question was recently asked at 'Exterro,Equator Business Solutions'.This question is still unanswered. Can you please provide an answer.}

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

_{Like Discuss Correct / Improve Asked in 2 Companies}

Q1482. Does Java SE has Immutable collections ?

Ans. Yes wef from Java 9

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

_{Like Discuss Correct / Improve java 9 java9 immutable immutability collections}

Q1483. Can you write immutable class without final?

Ans. By making the constructor private

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

_{Like Discuss Correct / Improve Asked in 1 Companies}

Q1484. Is java fully platform independent ?

Ans. yes, Java is a class-based and object-oriented programming language. It is a platform-independent language i.e. the compiled code can be run on any java supporting platform. It runs on the logic of “Write once, run anywhere”.

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

_{Like Discuss Correct / Improve Asked in 1 Companies}

Q1485. Can we use try within catch block ?

Ans. Yes

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

_{Like Discuss Correct / Improve Asked in 1 Companies}

Q1486. Isnt the use of HashTable and ConcurrentHashMap the same, i.e providing synchronized map collection ?

Ans. Both provide the thread safety but the actual difference come when talk about performance. CHM gives best performance when no of writer threads are less in number.

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

_{Like Discuss Correct / Improve synchronized collections hashtable ConcurrentHashMap Asked in 1 Companies}

Q1487. Will it print the message in Base Class constructor if we execute main method of Main class ? why ?

public class BaseClass {
BaseClass(){
System.out.println("Hello I am in Base Class Constructor");
}
}

public class DerivedClass extends BaseClass{
}

public class Main {

public static void main(String[] args) {
DerivedClass derivedClass = new DerivedClass();
}
}

Ans. Yes.

When the Derived class constructor is initialized , a no argument super will be called intrinsically.

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

_{Like Discuss Correct / Improve constructor}

Q1488. What will the following print upon executing main method of Main class ?

public class BaseClass {
BaseClass(){
System.out.println("Hello I am in Base Class Constructor");
}
}

public class DerivedClass extends BaseClass{
DerivedClass(){
System.out.println("Hello I am in Derived Class Constructor");
}
}

public class Main {

public static void main(String[] args) {
DerivedClass derivedClass = new DerivedClass();
}
}

Ans. Hello I am in Base Class Constructor
Hello I am in Derived Class Constructor

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

_{Like Discuss Correct / Improve constructor}

Q1489. What will the following code print upon executing main method of Main class ?

public class BaseClass {
BaseClass(){
System.out.println("Hello I am in Base Class Constructor");
}
}

public class DerivedClass extends BaseClass{
DerivedClass(){
System.out.println("Hello I am in Derived Class Constructor");

super();
}
}

public class Main {

public static void main(String[] args) {
DerivedClass derivedClass = new DerivedClass();
}
}

Ans. There will be compilation error within constructor of Derived Class as "super must be the first statement in constructor body".

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

_{Like Discuss Correct / Improve constructor}

Q1490. What will the following code print upon executing main method of Main class ?

public class BaseClass {
BaseClass(int x){
System.out.println("Hello I am in Base Class Constructor");
}
}

public class DerivedClass extends BaseClass{
DerivedClass(){
System.out.println("Hello I am in Derived Class Constructor");
}
}

public class Main {

public static void main(String[] args) {
DerivedClass derivedClass = new DerivedClass();
}
}

Ans. Compilation error as there is no default constructor available in BaseClass.

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

_{Like Discuss Correct / Improve constructor}

previous 30

next 30