Explain different ways of creating a thread. Which one would you prefer and why ?

Correct Answer: When an object is passed by value, this means that a copy of the object is passed Thus, even if changes are made to that object, it doesn?t affect the original value When an object is passed by reference, this means that the actual object is not passed, rather a reference of the object is passed Thus, any changes made by the external method, are also reflected in all places

Correct Answer: Dynamic method dispatch which is also known as runtime polymorphism is a process in which a call to an overridden method is resolved at runtime rather than at compile-time In this process, an overridden method is called through the reference variable of a superclass The determination of the method to be called is based on the object being referred to by the reference variable

Correct Answer: Dynamic binding is orthogonal to dynamic linking Binding refers to the linking of a procedure call to the code to be executed in response to the call Dynamic binding It is associated with polymorphism and inheritance, it(also known as late binding) means that the code associated with a given procedure call is not known until the time of the call at run-time

Correct Answer: Cloning refers to creating duplicate copies of objects in java Shallow Cloning: Shallow cloning is a bitwise copy of an object New object is created which is an exact copy that of the original one In case any objects are referring the fields of these objects, just the references are copied Deep Cloning: In deep cloning, complete duplicate copy of the original copy is created Deep cloning creates not only the primitive values of the original objects but also copies all its sub objects as well Clonable interface is used to perform cloning in java

Correct Answer: Dealing with primitives as objects is easier at times Most of the objects collection store objects and not primitive types Many utility methods are provided by wrapper classes To get these advantages we need to use wrapper classes As they are objects, they can be stored in any of the collection and pass this collection as parameters to the methods Features of the Java wrapper Classes: - Wrapper classes convert numeric strings into numeric values - The way to store primitive data in an object - The valueOf() method is available in all wrapper classes except Character - All wrapper classes have typeValue() method This method returns the value of the object as its primitive type

Correct Answer: - A process is an execution of a program, while a Thread is a single execution sequence within a process - A process can contain multiple threads A Thread is sometimes called a lightweight process

Correct Answer: Java Collections Framework provides a well designed set of interfaces and classes that support operations on a collections of objects The most basic interfaces that reside in the Java Collections Framework are: Collection, which represents a group of objects known as its elements Set, which is a collection that cannot contain duplicate elements List, which is an ordered collection and can contain duplicate elements Map, which is an object that maps keys to values and cannot contain duplicate keys

Correct Answer: The Big-O notation simply describes how well an algorithm scales or performs in the worst case scenario as the number of elements in a data structure increases The Big-O notation can also be used to describe other behavior such as memory consumption Since the collection classes are actually data structures, we usually use the Big-O notation to chose the best implementation to use, based on time, memory and performance Big-O notation can give a good indication about performance for large amounts of data

Correct Answer: Enumeration is twice as fast as compared to an Iterator and uses very less memory However, the Iterator is much safer compared to Enumeration, because other threads are not able to modify the collection object that is currently traversed by the iterator Also, Iteratorsallow the caller to remove elements from the underlying collection, something which is not possible with Enumerations

Correct Answer: 1 2 3

Explanation:

In argument[0] = args;, the reference variable arg[0], which was referring to an array with two elements, is reassigned to an array (args) with three elements.
Output:
$ javac main_arguments.java
$ java main_arguments
1 2 3