Top 10 Java Interview Questions and Answers 2014

Top 10 Java Interview Questions and Answers 2014

• 1.
  TOP 10 JAVA INTERVIEW QUESTIONS& ANSWERS 2014 SOURCE -> hirist.com
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  What is JVM? Whyis Java called the ‘Platform Independent Programming Language’? #1 Java Virtual Machine, is an interpreter which accepts „Bytecode‟ and executes it. It primarily works on the notion of „compile once, run everywhere‟. The translation into Bytecode makes a program easier to be executed across a wide range of platforms JVMs for various platforms might vary in configuration but they all understand the same set of Bytecode     SOURCE -> hirist.com
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  Which two methods do youneed to implement for key Objects in HashMap ? #2 It must implement equals and hashcode method in Java Equals and hashcode method is used to put and get object from HashMap   SOURCE -> hirist.com
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  What is the Difference between JDK and JRE? #3 The“JDK” is the Java Development Kit. i.e., the JDK is bundle of software that you can use to develop Java based software The “JRE” is the Java Runtime Environment. I.e., the JRE is an implementation of the Java Virtual Machine which actually executes Java programs. Each JDK contains one (or more) JRE‟s along with the various development tools like the Java source compilers, bundling and deployment tools, debuggers, development libraries, etc.    SOURCE -> hirist.com
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  What is immutable object? Can youwrite immutable object? #4 Immutable classes are Java classes whose objects can not be modified once created Any modification in Immutable object result in a new object For example, is String is immutable in Java    SOURCE -> hirist.com
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  What are the Data Types supported byJava? #5 There are eight Primitive Data types supported by Java • Byte : 8-bit signed two‟s complement integer • Short : 16-bit signed two‟s complement integer. • Int : 32-bit signed two‟s complement integer. • Long : 64-bit signed two‟s complement integer. • Float, Double, Autoboxing, Unboxing   SOURCE -> hirist.com
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  What is Autobox ing and Unboxin g? #6 Autoboxing:The Java compiler brings about an automatic transformation of primitive type (int, float, double etc.) into their object equivalents or wrapper type (Integer, Float, Double,etc) for the ease of compilation. Unboxing: The automatic transformation of wrapper types into their primitive equivalent is known as Unboxing.   SOURCE -> hirist.com
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  What is Function Over-Riding and Over- Loadingin Java? #7 Over-Riding: An override is a type of function which occurs in a class which inherits from another class. An override function “replaces” a function inherited from the base class, but does so in such a way that it is called even when an instance of its class is pretending to be a different type through polymorphism. Over-Loading: Overloading is the action of defining multiple methods with the same name, but with different parameters. It is unrelated to either overriding or polymorphism. Functions in Java could be overloaded by two mechanisms ideally: • Varying the number of arguments. • Varying the Data Type.   SOURCE -> hirist.com
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  What is the difference betweenAr ray List and Linked List ? #8 Array List - Random access - Only objects can be added Linked List - Sequential access - Implemented using nodes linked to each other   SOURCE -> hirist.com
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  What is difference between CyclicBarrier and CountDownLa tch inJava #9 Main difference between both of them is that you can reuse CyclicBarrier even if Barrier is broken but you cannot reuse CountDownLatch in Java.  SOURCE -> hirist.com
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  What is the useof the ‘SimpleDa teFormat’ #10 SimpleDateFormat is one such concrete class which is widely used by Java developers for parsing and formatting of dates. This is also used to convert Dates to String and vice-versa.. Almost every Enterprise level Java Application invariably uses the SimpleDateFormat for handling user dates   SOURCE -> hirist.com
• 13.
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