Solution COMPUTER APPLICATION 10 -ICSE 31 October 2018 10:27:48 Computer Applications Solution (ICSE) X Contents Revision Tour I ...........................................................................................................3 Revision Tour II ........................................................................................................19 Class as the Basis of All Computation .....................................................................93 User-Defined Methods .........................................................................................126 Constructors .........................................................................................................170 Library Classes ......................................................................................................201 Encapsulation ........................................................................................................219 Arrays ....................................................................................................................239 String Manipulation ..............................................................................................296 Model Test Paper-1 ...............................................................................................325 Model Test Paper-2 ...............................................................................................335 Model Test Paper-3 ...............................................................................................345 Model Test Paper-4 ...............................................................................................355 Model Test Paper-5 ...............................................................................................363 Chapter 1 Revision Tour I Mental Drill A. Tick () the correct option. 1. Name the programming technique that implements programs as an organised collection of interactive objects. a. Procedure Oriented Programming b. Modular Programming c. Object Oriented Programming d. None of these Ans. c. Object Oriented Programming 2. Name the characteristics of Object Oriented Programming that hides the complexity and provides a simple interface. a. Encapsulation b. Polymorphism c. Abstraction d. Inheritance Ans. c. Abstraction 3. Which among the following operator is used to access individual members of an object? a. (dot) b. + (plus) c. – (minus) d. / (divide) Ans. a. (dot) 4. Which among the following modifier is used in a ‘class’? a. public b. default c. Both a and b d. None of these Ans. c. Both a and b 5. Which among the following is a valid class name? a. Simple Interest b. SimpleInterest c. 1SimpleInterest d. Simple@Interest Ans. b. SimpleInterest 6. Which among the following is a valid object name? a. obj1 b. 1obj c. Obj 1 d. Obj#1 Ans. a. obj1 5 Revision Tour I 7. Which among the following is a valid float literal? a. 12.36f b. 12.36F c. 12.36 d. Both a and b Ans. d. Both a and b 8. Which among the following is a valid octal integer literal? a. 0178 b. 675 c. 0675 d. 0X675 Ans. c. 0675 9. Which among the following is a valid method of initialising? a. boolean f=true; b. boolean f=True; c. boolean f=’true’; d. None of these Ans. a. boolean f=true; 10. Which among the following is not a punctuator? a. ; semicolon b. , comma c. : colon d. dot Ans. d. dot 11. Which among the following is not a primitive data type? a. int b. float c. String d. char Ans. c. String 12. What is the largest possible value that can be stored in short data type? a. 215-1 b. 231-1 c. 27-1 d. 263-1 Ans. a. 215-1 13. If a is of type int and b is of type float what would be the resultant data type of a+b? a. int b. float c. double d. short Ans. b. float B. State whether the following statements are True (T) or False (F). 1. Encapsulation refers to the art of hiding the complexities and giving a simple interface. F 2. Procedure Oriented Language follows top down approach. T 3. Java is an example of Object Oriented Language. T Computer Applications – X (ICSE Course) Answers 6 4. Hiding the complexity and giving a simple interface is called Inheritance. F 5. Abstraction is same as encapsulation. F 6. An object is called a class factory. F 7. A class is an instance of an object. F 8. A class is a mechanism to implement encapsulation. T 9. Data members in a class is used to represent the characteristic of an object. T 10. The new operator is used to create an object. T 11. It’s a rule to have a class-name beginning in capital letter. F C. Fill in the blanks. 1. A class is a template that binds together data and methods together. 2. The values in the attributes of an object is called the state of an object. 3. The dot operator is used to access the individual members of a class. 4. The keyword new is used to allocate memory space for an object. 5. The default and public access modifier is used with a class. 6. An object is an identity with certain characteristic and behaviour. 7. The values/attributes of the characteristics of an object are called the state of an object. 8. All the complexities of a program should be encapsulated in such a way so that abstraction is obtained. 9. Inheritance allows us to encompass the parent class’ state and behaviours into its child.. 10. Poly-means many and Morphism means forms. Section A Answer the following questions: 1. How are objects implemented in software? Ans. In a software the characteristics of an object are represented through data members and behaviour is represented through member functions. 2. What is abstraction? How is encapsulation related to it? Ans. Abstraction is a principle of Object Oriented Programming (OOP) that hide certain details and only show the essential features of the object. 3. Define Encapsulation. Ans. Encapsulation is a principle of Object Oriented Programming (OOP) that binds together characteristics and behaviour of an object into a single unit represented by a class. 7 Revision Tour I 4. What is Inheritance? Ans. Inheritance is the concept that when a class of objects is defined, any subclass that is defined can inherit the definitions of one or more general classes. 5. What is Object Oriented Programming? Ans. Object Oriented Programming (or OOP) is a technique of implementing programs which are organized as a co-interactive collection of objects, each of which represents an instance of a class. 6. State three differences between Procedure Oriented Language and Object Oriented Languages. Ans. Procedure Oriented Programming Object Oriented Programming A large program is divided into smaller A program is represented as an object. segments or procedures. More importance is given to the program More importance is given to the data rather rather than the data. than the program. It follows top down approach. It follows bottom up approach. 7. State the four characteristics/principles of Object Oriented Programming. Ans. Encapsulation, Abstraction, Polymorphism and Inheritance. 8. What are keywords? Give an example. Ans. A keyword is a reserved word that has a special significance to the compiler and cannot be used anywhere else other than what it is intended for. Example- for, if, else, while etc. 9. What are identifiers? Ans. Identifiers are the names of variables, methods, classes, packages and interfaces. 10. What is a literal? Ans. Literal is a constant value that can be assigned to a variable. 11. Why is an object called an instance of a class? Ans. An object is called an instance of a class as every object created from a class gets its own instances of the variables defined in the class. Multiple objects can be created from the same class. 12. Write one difference between primitive data type and composite data type. Ans. Fundamental data type Composite data type These are inbuilt data type provided by the These are data types created by the user using Java Language. fundamental or user defined data type or both. Computer Applications – X (ICSE Course) Answers 8 The size of it is fixed. The size of different user-defined data type depends upon the size of the individual components of it. These data types are available in all parts of These data types are available only as specified a program within a class. by the access specifiers. 13. Give one example each of primitive data type and composite data type. Ans. Primitive data type: int, short, boolean, char etc. Composite data type: class, arrays, interface etc. 14. State two differences between a class and an object. Ans. Object Class Class is a blueprint or template from which Object is an instance of a class. objects are created. Object is a real world entity such as pen, laptop, Class is a group of similar objects. mobile, bed, keyboard, mouse, chair etc. Object is a physical entity. Class is a logical entity. Object is created through new keyword mainly Class is declared using class keyword e.g. e.g. Student s1=new Student(); class Student{} Object is created many times as per Class is declared once. requirement. Class doesn’t allocated memory when it is Object allocates memory when it is created. created. 15. Give one point of difference between unary and binary operators. Ans. Unary operator works on a single operand and Binary operator works on 2 operands. 16. What do you understand by type conversion? Ans. Type conversion is the process of converting one Primitive data type to another primitive data type. It may be done either implicitly or explicitly. 17. State the difference between a Boolean literal and a character literal. Ans. A boolean literal consist of only two values