Question 1:

What is up-casting and what is down-casting? Explain it by using examples with code.

Question 2:

What is polymorphism? What are required to implement polymorphism?

Question3:

Implement a method to count number of a and A in the string, for example, if the string is String str = "ab12cd1A4"; the number of a and A in str is 2.

public class StringManipulation {

public static void main(String[] args) {

}

// implement this method

public static int numberofAs (String str) {

}

}

Question 4:

What are the differences between FlowLayout and BorderLayout?

Answer:

What is the default layout manager of JFrame and JPanel, respectively?

Answer