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Showing posts with label HYDERABAD. Show all posts
Showing posts with label HYDERABAD. Show all posts
Saturday, October 06, 2018
Technical Support Associate posts for Freshers at IBM Hyderabad
Sunday, September 30, 2018
Orbcomm Hyderabad vacancies for Automation Engineer
Automation Engineer: No of Positions : 1 ;
Role Overview
As a QA Automation Engineer, you will be involved throughout the development lifecycle of the Orbcomm team with particular responsibility in the quality assurance both software manual testing and test automation. You'll be involved in the converting business requirements to test scripts and test scenarios so that they can be effectively tested. You will be working closely with PM’s as ensure requirements are being met and to the correct quality, and you will conduct automated (and manual tests where necessary) to ensure the software created is fit for purpose. During testing you will be thinking “outside of the box” to understand the various scenarios and configurations that customers use to ensure quality is maintained and through doing so drive regression testing across the products. You will be responsible for defining and driving innovative automated testing strategies and toolsets into our overall development processes that support and enhance the current Quality Assurance processes. Ensure that all tests are executed and give regular feedback to the team lead on the status of quality.
Required:
Strong background in, and at least 5+ years of working in tooling or QA automation
Thorough understanding of SDLC, specifically automated QA processes in agile development environments
Experience in writing, executing and monitoring automated test suites using a variety of technologies including, strong in Selenium(Java), Cucumber, SoapUI, TestNG
Proficient with bug tracking and test management toolsets to support development processes
Strong working knowledge of testing fundamentals such as TDD & BDD
Proficient working with relational databases such as MySQL, Oracle.
Use appropriate measures and KPIs to validate and report on software quality
Advantageous:
Building test infrastructures using containerization technologies such as Docker and working within continuous delivery / continuous release pipeline processes
Testing enterprise applications deployed to cloud environments such as AWS
Knowledge on Telematic products.
Experience mentoring QA staff and end users on quality objectives and testing processes
Understanding of NoSQL database technologies such as MongoDB or DynamoDB
CTFL, ISTQB, CSQA or CSTE certified
Degree level qualifications in a technical related subject
SaaS experience
Proactive 'self-starter' attitude
Lifelong learner - thrives from developing and sharing knowledge.
Education: BE/BTech, ME/MTech, MCA or equivalent experience
Apply below
kommireddy.mallikarjunreddy@orbcomm.com
Orbcomm Hyderabad vacancies for Java Developer
Hi All,
We are looking for following position for our Hyderabad office. Looking forward for your referral
Java Developer: No of Positions – 2
Should have a BE / B.Tech / ME/ M.Tech / MCA / MS with consistently good academic record.
More than 5 -8 years of Strong Core Java Experience and advanced working knowledge of J2EE (JSPs, Servlets, Core Java, XML, Webservices and JDBC), Hibernate and Web Services related technologies…
Experience on AJAX, jQuery, HTML5,Spring would be an added advantage.
Experience on low level device interfaces would be an added advantage.
XML and Spring, Hibernate is a must for the position.
Should have strong SQL skills and developer experience on databases like MySQL, SQL Server, Oracle
Should have the ability to analyse the requirements and come up with the most appropriate solution.
Should be able to independently design the solution for quality and reusability.
Have the ability to pick up any ad-hoc technology and continuous curiosity for new technologies on the horizon.
Should be a good communicator - both verbal and written communication.
Extensive experience developing applications using Open Source Frameworks, IDEs, and Java Application Servers.
Solid understanding of SQL and Relational Database Management Systems.
Send resume below
Wednesday, September 26, 2018
Database Developer posts @Wipro for Candiates with 1-3 year Exp #Hyderabad
Wednesday, April 18, 2018
Friday, March 16, 2018
Thursday, March 15, 2018
Friday, March 09, 2018
Amazon is hiring for Non-Technical Process for Hyderabad Location
Amazon is hiring for Non-Technical Process for Hyderabad Location, this is a Contract Role for a period of 6 Months. Please find below Job description and eligibility. Please drop into the below venue if you are interested in applying for this position.
Interview Date: 10th March 2018
Walk-In Time: 10:00 AM - 3:00 PM
Venue:
Amazon Development Centre India Pvt Ltd
Building no. 12-C, 2nd Floor, Mindspace
Raheja IT Park, Madhapur
Ranga Reddy District, Hyderabad – 500081
Job Description
CSP Support Analyst
Through Create Space services, one can sell books, CDs, and DVDs for a fraction of the cost of traditional manufacturing, while maintaining more control over their materials. We make it simple to distribute publisher’s books, music, and video through Internet retail outlets, their own website, other bookstores, retailers, libraries, and academic institutions.
The Create Space Support Analyst will serve as the primary support interface for publishers & vendors using the Create Space services and ensure all their concerns are duly attended to such that the system works smoothly.
Opportunities await strong candidates looking for a fast-growing, dynamic, challenging, innovative, and fun work environment.
This is a unique opportunity to be a part of a revolutionary product that will change the way people read.
Process and respond to phone calls and emails received from publishers.
Experience in a technical support process, especially for web-enabled software products or services is highly preferred
Experience in a front line external (customer or supplier) facing role requiring email, voice or message board type of interactions with customers / external parties is highly preferred.
Excellent verbal and written communication skills required. Must be able to interact with an external party like customers and suppliers comfortably
Should be willing to work night shifts.
Should be able to understand a complex problem and respond to publishers.
Basic familiarity with web technologies and HTML is highly desirable
Strong analytical skills required. Must be able to understand problems that vendors are facing, categorize, document, and decide on a course of action on when and to whom to escalate
Detail oriented and process focused. Must be able to follow the process and document interactions as per requirements in clear and concise manner
Prior experience in process improvement initiatives or six sigma type of projects is preferred but not required
Eligibility
- Candidates must have completed graduation, 2017 pass out’s must have the provisional certificate or consolidated mark sheet
- Fresher’s or candidates with 0-3 years of work experience can apply
- Candidates must be willing to join immediately
Interview Process
- System based Voice Assessment.
- Face to Face Interviews.
Kindly acknowledge this mail and confirm your participation at the earliest. Candidates who have attended an interview for the same role in the last 6 months are not eligible to reapply. Please write back to me if you require further clarifications in this regard.
Please ask for Ruban upon Reaching the Venue, Candidates without interview invite will not be allowed to be part of the interview process. Please carry a valid ID Proof
Thanks & Regards,
Stephy Janet. E
Recruiting Coordinator | Intl Corp/Kindle Content | India
SJJANET@AMAZON.COM
Monday, February 05, 2018
Monday, January 29, 2018
Friday, December 15, 2017
CMR Institute Of Technology Hyderabad conducting Open Walkin for all graduates
Hyderabad Candidates:
Open walk-in recruitment drive on 16th Dec'17. No registration required.
Eligibility:
Degree: B.E, B.Tech, BSC, BCA, and MCA
Streams: CS, IT are eligible...(ECE and EEE students with certification in Java or testing are only eligible)...BSC and BCA students from all streams will be allowed except Chemistry.
Percentage: B.E / BTech / MCA - 65 % and above starting 10th to highest degree. BSC / BCA 60 % and above starting a 10th highest degree.
2016 and 2017 passed out students are only allowed.
Venue:
CMR Institute Of Technology, Kandlakoya Village, Medchal Road, Hyderabad.
Time: 8 AM to 3 PM
Date: 16th Dec'17
Wishing you all the best.
Tech Mahindra Hyderabad Hiring All graduates for the post of Tech Support via walkin
Company Name: Tech Mahindra.
Profile: tech support
Greetings from Tech Mahindra !!
Skills Required:
1.Should be very fluent in Urdu language and can speak English.
2. Minimum 12th passed / Intermediate, Graduates also eligible but not postgraduates.
3. Should be willing to work rotational shifts.
4. Transport is available for both sides.
5. Should know numbers in the Urdu language.
Skills Required:
1. Should be able to converse in URDU language and comprehend the English language
2.Should know numbers in the Urdu language
3. Should have experience in Voice process.
4. Knowledge of Telecom
5. Good knowledge of Customer Service, C-SAT, Customer Support
6. Commitment and need for a job - To gauge stability
7. Willing to work in rotational shifts.
8.Transport is available for both sides.
Contact HR: Rizwana
Walk-In Date: 16-Dec-2017
Walk In Timings: 9AM to 12PM
Documents to be carried:
1. Updated CV
2. Carry original ID proof like Adarcard/ Pancard / Voter ID
Venue:
Tech Mahindra, SEZ Tower 1,
Opp Ananth Technologies,
Besides Oracle, Hitec city,
Hyderabad.
Tuesday, December 12, 2017
Karvy Computershare Pvt Ltd hiring all graduates at Hyderabad Office Via Walkin
Company Name Karvy Computershare Pvt Ltd
Qualification Any Graduate
Experience 0 - 3 Years
Job Location Hyderabad
Job Role Back Office Executive
Salary INR 1,25,000 - 2,00,000 P.A
Karvy Job Description
KARVY Computershare Pvt Ltd conducting walk-in interviews at Hyderabad Location.
Designation: Trainee, Investor Relationship Officer, SB Officer.
Salary: 1.35 LPA to 2.50 LPA.
Karvy Computershare Requisites
Any Graduate, Any Post Graduate.
Good Communication skills.
No Night Shifts - No Transport.
Please note salary will be paid in the training period.
Typing Speed of 25WPM.
Ready to Join Immediate.
Fresher, 0 to 2 years of experience.
Knowledge of Mutual funds preferred.
Knowledge of computers.
6 Day Working (Monday to Saturday) (Alternate Saturday and Sunday Fixed OFF).
Karvy Computershare Interview Process
Ops, HR Screening (Communication check Round).
On-line Assessment.
Final Round of Interview.
If interested kindly walkin with the below documents for immediate offer roll-out
One Passport Photo.
All Academic Certificates Xerox Copies.
Experience related documents (Payslips, Appointment Letter, Recent Hike Letter if any).
Address proof and ID proof Photocopy.
Print out of this copy.
Karvy Walkin Details
Walkin Date: 13th and 14th December 2017
Walkin Time: 10:00 AM - 3:00 PM
Venue
Karvy Computershare Pvt Ltd,
Selenium Building - Ground Floor
Tower B | Plot 31-32 |
Gachibowli Financial District |
Nanakramguda | Hyderabad 500 032.
Landmark: Back Side of the ICICI Towers, ISB Road.
Recruiter Name: M Vijay Kishore
Friday, December 08, 2017
Very Important and frequently asked Java interview Questions in an interview 2018
VERY IMPORTANT JAVA INTERVIEW QUESTIONS :
1. What are the important features of Java 8 release?
Java 8 has been released in March 2014, so it’s one of the hot topics in java interview questions. If you answer this question clearly, it will show that you like to keep yourself up-to-date with the latest technologies.
Java 8 has been one of the biggest releases after Java 5 annotations and generics. Some of the important features of Java 8 are:
- – Interface changes with default and static methods
- – Functional interfaces and Lambda Expressions
- – Java Stream API for collection classes
- – Java Date Time API
Platform independence means that you can run the same Java Program on any Operating System. For example, you can write a java program in Windows and run it in Mac OS.
3. What is JVM and is it platform independent?
Java Virtual Machine (JVM) is the heart of Java programming language. JVM is responsible for converting bytecode into machine-readable code. JVM is not platform independent, that's why you have different JVM for different operating systems. We can customize JVM with Java Options, such as allocating minimum and maximum memory to JVM. It’s called virtual because it provides an interface that doesn’t depend on the underlying OS.
4. What is the difference between JDK and JVM?
Java Development Kit (JDK) is for development purpose and JVM is a part of it to execute the java programs.
JDK provides all the tools, executables and binaries required to compile, debug and execute a Java Program. The execution part is handled by JVM to provide machine independence.
5. What is the difference between JVM and JRE?
Java Runtime Environment (JRE) is the implementation of JVM. JRE consists of JVM and java binaries and other classes to execute any program successfully. JRE doesn’t contain any development tools like java compiler, debugger etc. If you want to execute any java program, you should have JRE installed.
6. Which class is the superclass of all classes?
java.lang.Object is the root class for all the java classes and we don’t need to extend it.
7. Why Java doesn’t support multiple inheritance?
Java doesn’t support multiple inheritance in classes because of “Diamond Problem”.
However multiple inheritance is supported in interfaces. An interface can extend multiple interfaces because they just declare the methods and implementation will be present in the implementing class. So there is no issue of diamond problem with interfaces.
8. Why Java is not pure Object Oriented language?
Java is not said to be pure object oriented because it support primitive types such as int, byte, short, long etc. I believe it brings simplicity to the language while writing our code. Obviously java could have wrapper objects for the primitive types but just for the representation, they would not have provided any benefit.
As we know, for all the primitive types we have wrapper classes such as Integer, Long etc that provides some additional methods.
9. What is difference between path and classpath variables?
PATH is an environment variable used by operating system to locate the executables. That’s why when we install Java or want any executable to be found by OS, we need to add the directory location in the PATH variable.
Classpath is specific to java and used by java executables to locate class files. We can provide the classpath location while running java application and it can be a directory, ZIP files, JAR files etc.
10. What is the importance of main method in Java?
main() method is the entry point of any standalone java application. The syntax of main method is public static void main(String args[]).
main method is public and static so that java can access it without initializing the class. The input parameter is an array of String through which we can pass runtime arguments to the java program.
11. What is overloading and overriding in java?
When we have more than one method with same name in a single class but the arguments are different, then it is called as method overloading.
Overriding concept comes in picture with inheritance when we have two methods with same signature, one in parent class and another in child class. We can use @Override annotation in the child class overridden method to make sure if parent class method is changed, so as child class.
12. Can we overload main method?
Yes, we can have multiple methods with name “main” in a single class. However if we run the class, java runtime environment will look for main method with syntax as public static void main(String args[]).
13. Can we have multiple public classes in a java source file?
We can’t have more than one public class in a single java source file. A single source file can have multiple classes that are not public.
14. What is Java Package and which package is imported by default?
Java package is the mechanism to organize the java classes by grouping them. The grouping logic can be based on functionality or modules based. A java class fully classified name contains package and class name. For example, java.lang.Object is the fully classified name of Object class that is part of java.lang package.
java.lang package is imported by default and we don’t need to import any class from this package explicitly.
15. What are access modifiers?
Java provides access control through public, private and protected access modifier keywords. When none of these are used, it’s called default access modifier.
A java class can only have public or default access modifier.
16. What is final keyword?
final keyword is used with Class to make sure no other class can extend it, for example String class is final and we can’t extend it.
We can use final keyword with methods to make sure child classes can’t override it.
final keyword can be used with variables to make sure that it can be assigned only once. However the state of the variable can be changed, for example we can assign a final variable to an object only once but the object variables can change later on.
Java interface variables are by default final and static.
17. What is a static keyword?
static keyword can be used with class level variables to make it global i.e all the objects will share the same variable.
static keyword can be used with methods also. A static method can access only static variables of class and invoke only static methods of the class.
18. What is finally and finalize in java?
finally, block is used with try-catch to put the code that you want to get executed always, even if an exception is thrown by the try-catch block. finally block is mostly used to release resources created in the try block.
finalize() is a special method of Object class that we can override in our classes. This method get’s called by the garbage collector when the object is getting garbage collected. This method is usually overridden to release system resources when the object is garbage collected.
19. Can we declare a class as static?
We can’t declare a top-level class as static however an inner class can be declared as static. If inner class is declared as static, it’s called static nested class.
The static nested class is same as any other top-level class and is nested for only packaging convenience.
20. What is a static import?
If we have to use any static variable or method from other class, usually we import the class and then use the method/variable with the class name.
import java.lang.Math;
//inside class
double test = Math.PI * 5;
We can do the same thing by importing the static method or variable only and then use it in the class as if it belongs to it.
import static java.lang.Math.PI;
//no need to refer class now
double test = PI * 5;
Use of static import can cause confusion, so it’s better to avoid it. Overuse of static import can make your program unreadable and unmaintainable.
21. What is try-with-resources in java?
One of the Java 7 features is a try-with-resources statement for automatic resource management. Before Java 7, there was no auto resource management and we should explicitly close the resource. Usually, it was done in the final block of a try-catch statement. This approach used to cause memory leaks when we forgot to close the resource.
From Java 7, we can create resources inside try block and use it. Java takes care of closing it as soon as the try-catch block gets finished.
22. What is a multi-catch block in java?
Java 7 one of the improvement was a multi-catch block where we can catch multiple exceptions in a single catch block. This makes our code shorter and cleaner when every catch block has similar code.
If a catch block handles multiple exceptions, you can separate them using a pipe (|) and in this case, exception parameter (ex) is final, so you can’t change it.
23. What is static block?
Java static block is the group of statements that gets executed when the class is loaded into memory by Java ClassLoader. It is used to initialize static variables of the class. Mostly it’s used to create static resources when the class is loaded.
24. What is an interface?
Interfaces are a core part of Java programming language and used a lot not only in JDK but also java design patterns, most of the frameworks and tools. Interfaces provide a way to achieve abstraction in Java and used to define the contract for the subclasses to implement.
Interfaces are good for starting point to define Type and create a top-level hierarchy in our code. Since a Java class can implement multiple interfaces, it’s better to use interfaces as a superclass in most of the cases.
25. What is an abstract class?
Abstract classes are used in java to create a class with some default method implementation for subclasses. An abstract class can have an abstract method without body and it can have methods with implementation also.
the abstract keyword is used to create an abstract class. Abstract classes can’t be instantiated and mostly used to provide a base for sub-classes to extend and implement the abstract methods and override or use the implemented methods in abstract class.
26. What is the difference between abstract class and interface?
the abstract keyword is used to create abstract class whereas an interface is the keyword for interfaces.
Abstract classes can have method implementations whereas interfaces can’t.
A class can extend only one abstract class but it can implement multiple interfaces.
We can run abstract class if it has main() method whereas we can’t run an interface.
27. Can an interface implement or extend another interface?
Interfaces don’t implement another interface, they extend it. Since interfaces can’t have method implementations, there is no issue of the diamond problem. That’s why we have multiple inheritances in interfaces i.e an interface can extend multiple interfaces.
From Java 8 onwards, interfaces can have default method implementations. So to handle the diamond problem when a common default method is present in multiple interfaces, it’s mandatory to provide an implementation of the method in the class implementing them.
28. What is Marker interface?
A marker interface is an empty interface without any method but used to force some functionality in implementing classes in Java. Some of the well-known marker interfaces are Serializable and Cloneable.
29. What are Wrapper classes?
Java wrapper classes are the Object representation of eight primitive types in Java. All the wrapper classes in Java are immutable and final. Java 5 autoboxing and unboxing allows easy conversion between primitive types and their corresponding wrapper classes.
30. What is Enum in Java?
Enum was introduced in Java 1.5 as a new type whose fields consists of a fixed set of constants. For example, in Java, we can create Direction as an enum with fixed fields as EAST, WEST, NORTH, SOUTH.
enum is the keyword to create an enum type and similar to a class. Enum constants are implicitly static and final.
31. What are Java Annotations?
Java Annotations provide information about the code and they have no direct effect on the code they annotate. Annotations are introduced in Java 5. Annotation is metadata about the program embedded in the program itself. It can be parsed by the annotation parsing tool or by the compiler. We can also specify annotation availability to either compile time only or till runtime also. Java Built-in annotations are @Override, @Deprecated and @SuppressWarnings.
32. What is Java Reflection API? Why it’s so important to have?
Java Reflection API provides the ability to inspect and modify the runtime behavior of java application. We can inspect a java class, interface, enum and get their methods and field details. Reflection API is an advanced topic and we should avoid it in normal programming. Reflection API usage can break the design pattern such as Singleton pattern by invoking the private constructor i.e violating the rules of access modifiers.
Even though we don’t use Reflection API in normal programming, it’s very important to have. We can’t have any frameworks such as Spring, Hibernate or servers such as Tomcat, JBoss without Reflection API. They invoke the appropriate methods and instantiate classes through reflection API and use it a lot for other processing.
33. What is a composition in java?
The composition is the design technique to implement has-a relationship in classes. We can use Object composition for code reuse.
Java composition is achieved by using instance variables that refer to other objects. The benefit of using composition is that we can control the visibility of another object to client classes and reuse only what we need.
34. What is the benefit of Composition over Inheritance?
One of the best practices of Java programming is to “favor composition over inheritance”. Some of the possible reasons are:
Any change in the superclass might affect subclass even though we might not be using the superclass methods. For example, if we have a method test() in the subclass and suddenly somebody introduces a method test() in the superclass, we will get compilation errors in a subclass. The composition will never face this issue because we are using only what methods we need.
Inheritance exposes all the superclass methods and variables to the client and if we have no control in designing superclass, it can lead to security holes. Composition allows us to provide restricted access to the methods and hence more secure.
We can get runtime binding in composition where inheritance binds the classes at compile time. So composition provides flexibility in the invocation of methods.
35. How to sort a collection of custom Objects in Java?
We need to implement Comparable interface to support sorting of custom objects in a collection. The comparable interface has compareTo(T obj) method which is used by sorting methods and by providing this method implementation, we can provide a default way to sort custom objects collection.
However, if you want to sort based on different criteria, such as sorting an Employees collection based on salary or age, then we can create Comparator instances and pass it as sorting methodology.
36. What is an inner class in java?
We can define a class inside a class and they are called nested classes. Any non-static nested class is known as inner class. Inner classes are associated with the object of the class and they can access all the variables and methods of the outer class. Since inner classes are associated with the instance, we can’t have any static variables in them.
We can have local inner class or anonymous inner class inside a class.
37. What is an anonymous inner class?
A local inner class without a name is known as anonymous inner class. An anonymous class is defined and instantiated in a single statement. Anonymous inner class always extend a class or implement an interface.
Since an anonymous class has no name, it is not possible to define a constructor for an anonymous class. Anonymous inner classes are accessible only at the point where it is defined.
38. What is Classloader in Java?
Java Classloader is the program that loads bytecode program into memory when we want to access any class. We can create our own classloader by extending ClassLoader class and overriding loadClass(String name) method.
39. What are different types of classloaders?
There are three types of built-in Class Loaders in Java:
Bootstrap Class Loader – It loads JDK internal classes, typically loads rt.jar and other core classes.
Extensions Class Loader – It loads classes from the JDK extensions directory, usually $JAVA_HOME/lib/ext directory.
System Class Loader – It loads classes from the current classpath that can be set while invoking a program using -cp or -classpath command line options.
40. What is a ternary operator in java?
Jaa ternary operator is the only conditional operator that takes three operands. It’s a one-liner replacement for if-then-else statement and used a lot in java programming. We can use ternary operator if-else conditions or even switch conditions using nested ternary operators.
41. What does super keyword do?
the super keyword can be used to access superclass method when you have overridden the method in the child class.
We can use super keyword to invoke super class constructor in child class constructor but in this case it should be the first statement in the constructor method.
package com.journaldev.access;
public class SuperClass {
public SuperClass(){
}
public SuperClass(int i){}
public void test(){
System.out.println(“super class test method”);
}
}
Use of super keyword can be seen in below child class implementation.
package com.journaldev.access;
public class ChildClass extends SuperClass {
public ChildClass(String str){
//access super class constructor with super keyword
super();
//access child class method
test();
//use super to access super class method
super.test();
}
@Override
public void test(){
System.out.println(“child class test method”);
}
}
42. What is break and continue statement?
We can use break statement to terminate for, while, or do-while loop. We can use a break statement in a switch statement to exit the switch case. You can see the example of break statement at java break. We can use break with a label to terminate the nested loops.
The continue statement skips the current iteration of a for, while or do-while loop. We can use continue statement with label to skip the current iteration of outermost loop.
43. What is this keyword?
this keyword provides reference to the current object and it’s mostly used to make sure that object variables are used, not the local variables having same name.
//constructor
public Point(int x, int y) {
this.x = x;
this.y = y;
}
We can also use this keyword to invoke other constructors from a constructor.
public Rectangle() {
this(0, 0, 0, 0);
}
public Rectangle(int width, int height) {
this(0, 0, width, height);
}
public Rectangle(int x, int y, int width, int height) {
this.x = x;
this.y = y;
this.width = width;
this.height = height;
}
44. What is default constructor?
No argument constructor of a class is known as default constructor. When we don’t define any constructor for the class, java compiler automatically creates the default no-args constructor for the class. If there are other constructors defined, then compiler won’t create default constructor for us.
45. Can we have try without catch block?
Yes, we can have a try-finally statement and hence avoiding catch block.
46. What is Garbage Collection?
Garbage Collection is the process of looking at heap memory, identifying which objects are in use and which are not, and deleting the unused objects. In Java, the process of deallocating memory is handled automatically by the garbage collector.
We can run the garbage collector with code Runtime.getRuntime().gc() or use utility method System.gc().
47. What are Serialization and Deserialization?
We can convert a Java object to a Stream that is called Serialization. Once an object is converted to Stream, it can be saved to file or send over the network or used in socket connections.
The object should implement Serializable interface and we can use java.io.ObjectOutputStream to write object to file or to any OutputStream object.
The process of converting stream data created through serialization to Object is called deserialization.
48. How to run a JAR file through command prompt?
We can run a jar file using java command but it requires a Main-Class entry in jar manifest file. Main-Class is the entry point of the jar and used by java command to execute the class.
49. What is the use of System class?
Java System Class is one of the core classes. One of the easiest ways to log information for debugging is System.out.print() method.
System class is final so that we can’t subclass and override its behavior through inheritance. System class doesn’t provide any public constructors, so we can’t instantiate this class and that’s why all of its methods are static.
Some of the utility methods of System class are for array copy, get the current time, reading environment variables.
50. What is an instanceof keyword?
We can use an instanceof keyword to check if an object belongs to a class or not. We should avoid it’s usage as much as possible. Sample usage is:
public static void main(String args[]){
Object str = new String(“abc”);
if(str instanceof String){
System.out.println(“String value:”+str);
}
if(str instanceof Integer){
System.out.println(“Integer value:”+str);
}
}
Since str is of type String at runtime, first if statement evaluates to true and second one to false.
51. Can we use String with switch case?
One of the Java 7 features was an improvement of switch case of allowing Strings. So if you are using Java 7 or higher version, you can use String in switch-case statements.
52. Java is Pass by Value or Pass by Reference?
This is a very confusing question, we know that object variables contain a reference to the Objects in heap space. When we invoke any method, a copy of these variables is passed and gets stored in the stack memory of the method. We can test any language whether it passes by reference or pass by value through a simple generic swap method.
53. What is the difference between Heap and Stack Memory?
The major difference between Heap and Stack memory are as follows:
Heap memory is used by all the parts of the application whereas stack memory is used only by one thread of execution.
Whenever an object is created, it’s always stored in the Heap space and stack memory contains the reference to it. Stack memory only contains local primitive variables and reference variables to objects in heap space.
Memory management in the stack is done in LIFO manner whereas it’s more complex in Heap memory because it’s used globally.
54. Java Compiler is stored in JDK, JRE or JVM?
The task of java compiler is to convert java program into bytecode, we have javac executable for that. So it must be stored in JDK, we don’t need it in JRE and JVM is just the specs.
55. What will be the output of following programs?
static method in class
package com.journaldev.util;
public class Test {
public static String toString(){
System.out.println(“Test toString called”);
return “”;
}
public static void main(String args[]){
System.out.println(toString());
}
}
Answer: The code won’t compile because we can’t have an Object class method with the static keyword. Note that Object class has toString() method. You will get compile time error as “This static method cannot hide the instance method from Object”. The reason is that static method belongs to the class and since every class base is Object, we can’t have the same method in the instance as well as in class. You won’t get this error if you change the method name from toString() to something else that is not present in superclass Object.
static method invocation
package com.journaldev.util;
public class Test {
public static String foo(){
System.out.println(“Test foo called”);
return “”;
}
public static void main(String args[]){
Test obj = null;
System.out.println(obj.foo());
}
}
Answer: Well this is a strange situation. We all have seen NullPointerException when we invoke a method on an object that is NULL. But here this program will work and prints “Test foo called”.
The reason for this is the java compiler code optimization. When the java code is compiled to produced bytecode, it figures out that foo() is a static method and should be called using class. So it changes the method call obj.foo() to Test.foo() and hence no NullPointerException.
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