About ISC Computer Practical – writing the program and Viva Voce Questions

ISC students get three programs in their computer practical and they have to answer only one. Fiirstly they have to write the program on their copy along with algorithm and variable descriptions. Once they have completed their writing job, they cannot modify their copy anymore.

The next step of the practical examination is that they will edit the program on BlueJ editor following their copy. It may happen that the program may show many errors – compile time or run time. There may be logical error also. Don’t worry, rectify the program on computer but don’t try to rectify in your copy. Certain percentage of deviation between the program on your copy and computer is permitted.

Atleast one program of ISC computer practical is based on String class. In viva, details about different String class methods (which are used in your program) are asked by the external examiner. Return type of the methods, other overloaded versions of the methods may be asked. In your program there may be ‘throws’ clause. The examiner may ask the meaning of throws – what actually it throws and to whom. The examiner may ask in viva about Exception handling.

Difference between bubble sort and selection sort is a common question in ISC computer practical examination viva. My observation is that most of the students do not use ‘break’ in bubble sort (I am also an external examiner of a school for last 4-5 years). Students should know the utility of ‘break’ statement in bubble sort.

If there is any program where StringTokenizer class is used, in viva the examiner may ask about the other overloaded version of constructors of the class.

BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); - questions may come from the above statement. What is System.in? What is the need of creating object of InputStreamReader by using the statement new InputStreamReader? Who carries the terminal input towards program in the above statement?

Regarding Exception handling - what is the difference between throws and try...catch.

Use of valueOf () function of String class and toString () function of Object class.

valueOf () is a static function of String class which converts any type of non string value into String object.
toString () is a function of Object which is automatically called by java compiler when any non string value is passed as argument in print () and println() function. This function also converts the non string value into string value. Example:
System.out.println("Value="+a)
Suppose value of 'a' is 5. The function toString () will be called automatically and numeric 5 will be converted into "5". Here '+' operator concatenates the strings "Value=" and "5" into "Value=5".

Describe each terms of System.out.println()

System.is a class of java.lang package. 'out' is the object of PrintWriter class of Java.io package which is a static data member of System class and println () is the function of PrintWriter class.

Example of operator overloading in java

print () and println () functions displays only string values. In the statement System.out.println("Value="+a), addition between a string value and an numeric value is not possible. toString () function of Object class converts the numeric value into string value and then '+' operator concatenates the string values into one string value. This is an example of operator overloading.

I wish Best of luck to all students appearing in computer practical examination on 20th February 2014.