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JAVA INTERVIEW QUESTIONS AND ANSWERS EBOOK

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resourceone.info: Java Interview Questions & Answers eBook: Venkatesh: Kindle Store. JAVA: Top Java Interview Questions with Answers - Kindle edition by NEELAM. Download it once and read it on your Kindle device, PC, phones or tablets. Java Interview Questions & Answers is a collection of all latest and most frequently asked interview questions with their detailed and precise answers. This book.


Java Interview Questions And Answers Ebook

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Most Important Java Interview Questions and Answers: Crack That Next Interview With Higher Salary In Less Preparation Time eBook: Vamsee Puligadda. I was getting a lot of emails and comments to create java interview questions and answers PDF eBook. It was hard and time taking, but finally, it's done. (a) CORE JAVA Interview Questions, Answers and proven strategies for getting hired as an IT professional (b) Dozens of examples to respond to interview.

This is clearly the right book for Java developer doesn't matter if you are going to core Java, J2EE or Android interview.

Java Interview Questions and Answers PDF eBook Free Download (250+ Questions, 60 Pages)

I cannot recommend this book enough, certainly you need a copy of it in yourself to prepare for both telephonic and face-to-face Java interviews. Before they released the Java Programming interview exposed, I used to read this book because it also covers a lot of good topics e. A good thing about this book is that it also covers non-technical interviews e. HR interview and how to negotiate with them.

Certainly a great book to prepare for programming job interview, even today I still refer this book to refresh my concepts, particularly on data structure and algorithms. Cracking the Coding Interview: Programming Questions and Solutions This is the third great book to prepare for Java and Programming job interviews.

It's very similar to the previous book Programming Interviews Exposed, but it got more questions and also covers more topics. Pass by value and Pass by reference is an age old programming concept, where Pass by value passes only the value of a variable in a method call, where pass by reference passes the address of the variable via pointers to the method, hence any changes to the variable in the called function actually reflects the change in the called function. Java is Pass by Value, and does not support Pass by Reference.

Related Questions: Primitive data types are passed by reference or pass by value? Everything in java is passed by Value. Objects are passed by value or by reference? Pass By Value, friends. Differentiate between HashMap and Map?

HashMap itself is an unordered collection, and does not follow the order of insertion. HashMap internally uses the hashing algorithm and buckets to put objects in memory, and gives an O 1 time complexity for insertion and retrieval of values, hence has an clear advantage over the other Data Structures.

Differences between HashMap and HashTable? Preferred when we are not Thread Safe and Synchronized. Performance trade-off due to An equivalent thread safe map can be created by synchronization overhead.

No guarantee over the order of insertion in HashMap. All the data is kept in the order of insertion in HashTables.

Suggested by Java. Differentiate between Vector and ArrayList? The Vector class was deprecated by Java when they introduced the ArrayList class. The differences between Vector and ArrayList are: Vector ArrayList Deprecated Class. New implementation provided by Java. Thread safe and Synchronized.

Un-Synchronized, thread unsafe. There is a little performance trade-off with Better performance than Vectors. Differentiate between Map and Set? Set holds unique values, whereas the Map holds unique Keys and can have any amount of duplicate Values assigned to the unique keys.

Maps are part of java collection framework but do not extend the Collection Interface, Set is a part of collection framework and also extends Collection Interface.

Differentiate between AWT and Swing? What is the difference between a constructor and any ordinary method? Constructor is a special method that is used to initialize objects before we start using them. A constructor does not have a return type and has the same name as the class name itself. Java provides a default constructor to every class unless the programmer has defined any constructor himself.

The default constructor enables us to create objects of our class by the line of code: What is an Iterator?

Iterator is just another java object that lets you iterate over an java collection. Yes you can always use our favorite foreach loop to scan over the collection, but sometimes we may need to modify the collection while in iteration, here the iterator comes to our rescue.

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We can remove the element from the iterator while being inside the iteration iterators are fail fast , the foreach loop would blow off in this situation with a ConcurrentModificationException. Again we must be clear that there are two obvious ways for accessing Java Interview Again there is a third way with static methods and static variables that can be accessed directly by the class name.

Now discussing about the access modifiers: This is the most relaxed access modifier. It is not available to any class extending it, nor can be accessed by objects of the class.

Outside the package protected access specified properties are only accessible via Inheritance. This is another restrictive access modifier. There is no way to access a default property outside the package. We insist you to type down the code below, and play with it to get your concepts in place.

Typing just two Java classes should not be a very difficult task. What is the significance of a static modifier? On a direct note: Everything is packed inside that little object in the Heap, and if we have 10 such objects created, each of these little objects would have their own properties and methods working on those properties, such that on modifying any property of the first object would have no effect on the other 9 objects. So basically we have 10 people with their own data, and their own powers.

Now say we need to have a data that needs to be shared across these 10 people, what do we do? Just for the information, the static data lands up in the Heap only — a special heap area known as perm heap or permanent generation , but not inside an object or the Heap where objects are present.

This area contains all static data of any class along with other metadata information. We would be talking a little over this in the third section of the book in the Java Memory Allocation question. Greedy for learning more? Go on, do some surfing over it, you might learn something totally awesome.

Different usage of static key word: Static variable: One per class, shared variable. Static Method: Belongs to class, similar to static variable. It can access only static data and static methods directly.

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Else we need to create object of the class and call the methods from the object exactly what we do in our main method most of the times. A static method cannot use32 the this and super keyword inside itself. It can also be accessed via thePage ClassName. Java Interview Static Block: Your program can also have an interesting thing known as the static block.

A static block is a piece of code which you want to execute before any part of your class is used. A static blocks is the 1st thing that would be executed by the JVM, even before the constructor. The static block would be executed only once. Open your IDE and try this piece of code instantly and observe the order of execution: Anything that is marked final in java becomes final i.

Page committed. A variable marked final cannot be changed by re-assigning any value to it again. Any Java Interview And any class marked final cannot be extended by any other class. Can main method be declared as private?

Why not, there is no compilation error for sure if my main method is private; but then I am not able to run my code. Wondering why? Who calls our program.. Etc etc.. So it requests you — please provide me a main method which I can call.

Where can I get Core Java interview questions and answers with explanation?

I would be treating this method as the entry point to your program. Now, How does the JVM make the method call? Simple, it just uses the ClassName. So understanding this, we can now think that if the main is not public, how would it be visible to the JVM. What if the static modifier is removed from the main method signature?

What if I do not provide the String array as the argument to the method? VM would again Fail, not being able to find the correct method. What if I write static public void main, instead of public static void main? Its just fine. No issues here.

What is the first argument of the String array in main method? It just holds the parameters provided to the program.

If I do not provide any arguments on the command line, then the String array of Main method will be empty or null? How can we check if the argument array is empty or NULL? We can check it programmatically: Why not, just while executing you must specify the entry point class name, where it should look for the main method.

Generally it makes more sense to have only one main, since there should logically one entry point only in the applications. So in case of multiple main application, while bundling the application the entry point has to be specified which the JVM would call to use the application.

Generally you would distribute your application as a JAR, and there you have to mention which class is going to be the entry point for the app. So even if you have multiple classes with multiple mains, The JVM knows which class to call. Related Question: Can I have multiple main methods in the same class? Yes, of course, all you are trying to do is overload the main method, so its all valid as long as they stand upto method overloading rules.

Do we have to import java. No, java.

You can assume JVM does that for us. Yes, a package can be imported N- number of times without any issue. Instead package import is just a qualified name of the class, i.

Math class. What are Checked and Un-Checked Exception? The exceptions are broadly classified into two types: Checked Exceptions: In general these are the exceptions which the programmer has to handle in his code because they are the ones very liable to occur.

UnChecked Exceptions: This is a relaxation from Java, since these arise only because of the programming logic issue or system errors these are not mandatory to be handled or are un-recoverable and therefore unhand able. The diagram below must buy you some more clarity: What are the differences between Error and Exceptions? Errors unlike exceptions are generally unrecoverable. Exceptions are both Checked and Unchecked, whereas all the Errors are Unchecked. Name an unrecoverable Error?

Does it mean that we cannot catch Errors? Yes we can catch them, but still there would be no guarantee of the code being stable, since Errors are mostly Unrecoverable. What is Dynamic Method Dispatching? Dynamic method dispatch is the mechanism by which a call to an overridden method is resolved at Run Time, rather than at Compile Time. Dynamic method dispatch is important because this is how Java implements Runtime Polymorphism. Method Overriding is a Runtime Polymorphism mechanism in java, where you can override the definition of any method in the parent class and provide your own new definition for the method.

Overriding is also known as Dynamic Method Invocation or Runtime Polymorphism, because the JVM itself does not know which method would be called until its executing the code at runtime.

Need Answers to the Top 10 Interview Questions?

It would give you the unresolved symbol compilation error. Which one should be preferred. In a program, multiple threads are creating thousands of large temporary StringBuilder objects. Life span of all those objects is 1 GC cycle. But somehow we are getting JVM pauses in our application. How would you troubleshoot the problem? What is difference between Primary Key and Unique Key?

What is clustered and non-clustered index in Sybase database?

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What is Outer and Inner Join? What is ADT?Can I have multiple main methods in the same class?

Thank you. Which is better, extending the Thread class or implementing the Runnable Interface? VM would again Fail, not being able to find the correct method. Flex 4 Cookbook.

Interviewing for a Java-related job can be difficult. What are the differences between Error and Exceptions? Get fast, free shipping with Amazon Prime.