Page 9 - ComputerScience_Class_11

The students are required to do lab assignments in the computer lab concurrently with the lectures.
Programming assignments should start with development of appropriate algorithm followed by coding
using Java and Python.
4. Introduction to Object Oriented Programming using Java
Note that topics 5 to 11 should be introduced almost simultaneously along with Classes and their
definitions.
5. Objects

(a) Objects as data (attributes) + behaviour (methods or methods); object as an instance of a class.
Difference between object and class should be made very clear. BlueJ (www.bluej.org) and Greenfoot
(www.greenfoot.org) can be used for this purpose.
(b) Analysis of some real-world programming examples in terms of objects and classes.
Use simple examples like a calculator, date, number etc. to illustrate how they can be treated as
objects that behave in certain well- defined ways and how the interface provides a way to access
behaviour. Illustrate behaviour changes by adding new methods, deleting old methods or modifying
existing methods.

(c) Basic concept of a virtual machine; Java Virtual Machine (JVM); compilation and execution of Java
programs (the javac and Java programs).
The JVM is a machine but built as a program and not through hardware. Therefore it is called a
virtual machine. To run, JVM machine language programs require an interpreter. The advantage is
that such JVM machine language programs (.class files) are portable and can run on any machine
that has the Java program.
(d) Compile time and run time errors; basic concept of an exception, the Exception class, try-catch,
throw, throws and finally.
Differentiate between compile time and run time errors. Run time errors crash the program.
Recovery is possible by the use of exceptions. Explain how an exception object is created and
passed up until a matching catch is found. This behaviour is different from the one where a value
is returned by a deeply nested method call.
6. Primitive values, Wrapper classes, Types and casting
Primitive values and types: byte, int, short, long, float, double, boolean, char. Corresponding wrapper
classes for each primitive type. Class as type of the object. Class as mechanism for user defined types.
Changing types through user defined casting and automatic type coercion for some primitive types.
Ideally, everything should be a class; primitive types are defined for efficiency reasons; each primitive
type has a corresponding wrapper class. Classes as user defined types. In some cases types are
changed by automatic coercion or casting – e.g. mixed type expressions. However, casting in general
is not a good idea and should be avoided, if possible.
7. Variables, Expressions
Variables as names for values; named constants (final), expressions (arithmetic and logical) and their
evaluation (operators, associativity, precedence). Assignment operation; difference between left-hand
side and right-hand side of assignment.
Variables denote values; variables are already defined as attributes in classes; variables have types that
constrain the values it can denote. Difference between variables denoting primitive values and object
values – variables denoting objects are references to those objects.
NOTE: Library functions for solving expressions may be used as and when required.