Question

Copyright laws were established A. to allow authors to distribute their work while maintaining certain ownership rights. B. to allow authors to maintain ownership of their ideas. C. to restrict access to publications to certain groups within society. D. to allow ideas to be traced back to their origins. Which of the following describes only the portion of a database available to a particular user? A. Database model B. Schema C. Subschema D. DBMS Which of the following relational operations combine data from more than one relation? A. SELECT B. PROJECT C. JOIN A class that cannot be instantiated is called a/an ____. a) Abstract class. b) Anonymous class. c) Concrete class. d) Non-inheritable. Which of the following statements about comparing objects is cancel? a) The equals method is used to compare whether two references arc to the same object. b)The equals c) The -- operator is used Co compare whether two objects have the same contents. d) The equal a method and the -- operator arc perform the same actions. In the following, which is the interface? public class ClassZ extends Class Y implements ClassX a. ClassX b. ClassY c. ClassZ d. None of the above To test whether an object belongs to a particular type, use _____. a) the this reserved word. b) the 8ubclaaaot reserved word. c) the instance of operator. d) the equals method. Event listeners are often installed as ____ classes so that they can have access to the surrounding fields, methods, and final variables. a) Inner b) Interface c) Abstract

Answer 1

Answers:

(27). (B) to allow authors to maintain ownership of their ideas.

The main idea of establishing the copyright law was to maintain the ownership. The author does so much research work and applies his/her creativity to do some writing. He/she may have invest so much time and money also in this task so no one should be able to use it without permission of the person who invented it. So this law protects the work.

(28). (C) Subschema

Subschema means the part of the schema which may or may not display the complete structure, some rules are applied before displaying the data so that only required things are displayed based on user as well.

(29). (C) JOIN

Join is the keyword which is used to merge 2 tables i.e. relations and display it as the single relation.

The join is applied to some common column on two relations and returns the results for which this column has same values in both the tables.

(30). (A) Abstract class

Abstract class can not have any object. This class shows the methods the objects are performed on, but how thie methods are performed, that is not mentioned so it gives abstract information and so it is abstract class.

(31). (B)

You can use both equals() and == for two objects in different way.
Both does not perform the same action.

== checks whether 2 objects points to i.e. references to the same object. If it is so, it returns true.

equals() method is used to compare the content of the object variables.

So, (B) is the correct option.

(32). (A) ClassX

In Java, class is always extended and the interface is always implemented.

So, the word extends specifies that ClassZ is extending ClassY functionality and ClassY is implementing ClassX which means ClassX is the interface whose methods are implemented in the ClassY.

(33). (C) the instanceof operator

instanceof operator is used to check whether the object is of particular class or not.

If you write obj instanceof c1, it returns true if 'obj' is the instance of class c1, otherwise it returns false.

(34). (A) Inner

The inner class can have access to the surrounding fields and methods as mentioned in the question so event listeners are written as inner classes.

Do comment if there is any question. Thank you. :)