Convergys Sample Technical Placement Paper

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Convergys Technical Latest Sample Placement Paper

1. What are printf and scanf call by reference or call by value?

ANS: Printf : Call by value Scanf : Call by reference

2. What is the important aspect of a real-time system or Mission Critical Systems?

ANS: A real time operating system has well defined fixed time constraints. Process must be done within the defined constraints or the system will fail. An example is the operating system for a flight control computer or an advanced jet airplane. Often used as a control device in a dedicated application such as controlling scientific experiments, medical imaging systems, industrial control systems, and some display systems. Real-Time systems may be either hard or soft real-time. Hard real-time: Secondary storage limited or absent, data stored in short term memory, or read-only memory (ROM), Conflicts with time-sharing systems, not supported by general-purpose operating systems. Soft real-time: Limited utility in industrial control of robotics, Useful in applications (multimedia, virtual reality) requiring advanced operating-system features.

3. What is the difference between Hard and Soft real-time systems?

ANS: A hard real-time system guarantees that critical tasks complete on time. This goal requires that all delays in the system be bounded from the retrieval of the stored data to the time that it takes the operating system to finish any request made of it. A soft real time system where a critical real-time task gets priority over other tasks and retains that priority until it completes. As in hard real time systems kernel delays need to be bounded.

4. What is the cause of thrashing? How does the system detect thrashing? Once it detects thrashing, what can the system do to eliminate this problem?



ANS: Thrashing is caused by under allocation of the minimum number of pages required by a process, forcing it to continuously page fault. The system can detect thrashing by evaluating the level of CPU utilization as compared to the level of multiprogramming. It can be eliminated by reducing the level of multiprogramming.

5. What is multi-tasking, multi programming, multi-threading?

ANS: Multi programming: Multiprogramming is the technique of running several programs at a time using timesharing. It allows a computer to do several things at the same time. Multiprogramming creates logical parallelism. The concept of multiprogramming is that the operating system keeps several jobs in memory simultaneously. The operating system selects a job from the job pool and a start executing a job, when that job needs to wait for any i/o operations the CPU is switched to another job. So the main idea here is that the CPU is never idle. Multi-tasking: Multitasking is the logical extension of multiprogramming .The concept of multitasking is quite similar to multiprogramming but difference is that the switching between jobs occurs so frequently that the users can interact with each program while it is running. This concept is also known as time-sharing systems. A time-shared operating system uses CPU scheduling and multiprogramming to provide each user with a small portion of time-shared system. Multi-threading: An application typically is implemented as a separate process with several threads of control. In some situations a single application may be required to perform several similar tasks for example a web server accepts client requests for web pages, images, sound, and so forth. A busy web server may have several of clients concurrently accessing it. If the web server ran as a traditional single-threaded process, it would be able to service only one client at a time. The amount of time that a client might have to wait for its request to



be serviced could be enormous. So it is efficient to have one process that contains multiple threads to serve the same purpose. This approach would multithread the web-server process, the server would create a separate thread that would listen for client requests when a request was made rather than creating another process it would create another thread to service the request. To get the advantages like responsiveness, Resource sharing economy and utilization of multiprocessor architectures multithreading concept can be used.

6. What is a string?

ANS: A combination of characters is called as string.

7. What is a package?

ANS: A package is a collection of classes and interfaces that provides a high-level layer of access protection and name space management.

8. How do you declare an array?

ANS: Array variable indicates the type of object that the array holds. Ex: int arr[];

9. What is a reflection package?

ANS: java.lang.reflect package has the ability to analyze itself in runtime.

10. What is the argument type of program’s main ( ) method?

ANS: String array.

11. What is an interface and its use?

ANS: Interface is similar to a class which may contain method’s signature only but not bodies and it is a formal set of method and constant declarations that must be defined by the class that implements it. Interfaces are useful for: a) Declaring methods that one or more classes are expected to implement b) Capturing similarities between unrelated classes without forcing a class relationship.



c) Determining an object’s programming interface without revealing the actual body of the class.

12. What is a compilation unit?

ANS: Java source code file.

13. What is an abstract class?

ANS: An abstract class is a class designed with implementation gaps for subclasses to fill in and is deliberately incomplete.

14. What declarations are required for every Java application?

ANS: A class and the main ( ) method declarations.

15. What is the difference between Integer and int?

ANS: a) Integer is a class defined in the java.lang package, whereas int is a primitive data type defined in the Java language itself. Java does not automatically convert from one to the other. b) Integer can be used as an argument for a method that requires an object, whereas int can be used for calculations.

16. What are the three OOPs principles and define them?

ANS: Encapsulation, Inheritance and Polymorphism are the three OOPs Principles. Encapsulation: Is the Mechanism that binds together code and the data it manipulates, and keeps both safe from outside interference and misuse? Inheritance: Is the process by which one object acquires the properties of another object? Polymorphism: Is a feature that allows one interface to be used for a general class of actions?

17. What is a cloneable interface and how many methods does it contain?



ANS: It is not having any method because it is a TAGGED or MARKER interface.

18. What are the two parts in executing a Java program and their purposes?

ANS: Two parts in executing a Java program are: Java Compiler and Java Interpreter. The Java Compiler is used for compilation and the Java Interpreter is used for execution of the application.

19. What is the difference between abstract class and interface?

ANS: a) All the methods declared inside an interface are abstract whereas abstract class must have at least one abstract method and others may be concrete or abstract. b) In abstract class, key word abstract must be used for the methods whereas interface we need not use that keyword for the methods. c) Abstract class must have subclasses whereas interface can’t have subclasses.

20. In order for a source code file, containing the public class Test, to successfully compile, which of the following must be true? A)It must have a package statement B)It must be named Test.java C)It must import java.lang D)It must declare a public class named Test

ANS: B

21. Can you have an inner class inside a method and what variables can you access?

ANS: Yes, we can have an inner class inside a method and final variables can be accessed.

22. What is the use of bin and lib in JDK?

ANS: Bin contains all tools such as javac, applet viewer, awt tool etc., whereas Lib contains all packages and variables.



23. What is the difference between String and String Buffer?

ANS: a) String objects are constants and immutable whereas StringBuffer objects are not. b) String class supports constant strings whereas StringBuffer class supports growable and modifiable strings.

24. What is the difference between constructor method and method?

ANS: Constructor will be automatically invoked when an object is created. Whereas method has to be call explicitly.

25. In Java, what is the difference between an Interface and an Abstract class?

ANS: An Abstract class declares have at least one instance method that is declared abstract which will be implemented by the subclasses. An abstract class can have instance methods that implement a default behavior. An Interface can only declare constants and instance methods, but cannot implement default behavior.

26. What is an array?

ANS: An array is an object that stores a list of items.

27. Can you have virtual functions in Java? Yes or No. If yes, then what are virtual functions?

ANS: Yes, Java class functions are virtual by default. Virtual functions are functions of subclasses that can be invoked from a reference to their superclass. In other words, the functions of the actual object are called when a function is invoked on the reference to that object.

28. How do you assign values to variables?

ANS: Values are assigned to variables using the assignment operator =.

29. What are the advantages of OOPL?

ANS: Object oriented programming languages directly represent the real life objects. The features of OOPL as inheritance, polymorphism and encapsulation make it powerful.



30. What do mean by polymorphism, inheritance and encapsulation?

ANS: Polymorphism: is a feature of OOPl that at run time depending upon the type of object the appropriate method is called. Inheritance: is a feature of OOPL that represents the "is a" relationship between different objects (classes). Say in real life a manager is a employee. So in OOPL manger class is inherited from the employee class. Encapsulation: is a feature of OOPL that is used to hide the information.

31. What do you mean by static methods?

ANS: By using the static method there is no need creating an object of that class to use that method. We can directly call that method on that class. For example, say class A has static function f(), then we can call f() function as A.f(). There is no need of creating an object of class A.

32. What is meant by variable?

ANS: Variables are locations in memory that can hold values. Before assigning any value to a variable, it must be declared.

33. What do you mean by virtual methods?

ANS: Virtual methods are used to use the polymorphism feature in C++. Say class A is inherited from class B. If we declare say function f() as virtual in class B and override the same function in class A then at runtime appropriate method of the class will be called depending upon the type of the object.

34. What are variable types?

ANS: Variable types can be any data type that java supports, which includes the eight primitive data types, the name of a class or interface and an array.

35. What do you mean by multiple inheritance in C++?

ANS: Multiple inheritance is a feature in C++ by which one class can be of different types. Say class teachingAssistant is inherited from two classes say teacher and Student.



36. What is a method?

ANS: Encapsulation of a functionality which can be called to perform specific tasks.

37. What is a class?

ANS: A class is a blueprint, or prototype, that defines the variables and the methods common to all objects of a certain kind. 38. What is an object?

ANS: An object is a software bundle of variables and related methods. An instance of a class depicting the state and behavior at that particular time in real world.

39. What is encapsulation? Explain with an example.

ANS: Encapsulation is the term given to the process of hiding the implementation details of the object. Once an object is encapsulated, its implementation details are not immediately accessible any more. Instead they are packaged and are only indirectly accessible via the interface of the object.

40. What is inheritance? Explain with an example.

ANS: Inheritance in object oriented programming means that a class of objects can inherit properties and methods from another class of objects.

Convergys Sample Technical Placement Paper

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