JNTU B.Tech II JAVA PROGRAMMING Previous Question Paper (April/May - 2023 - R13)

A Default Constructor is a constructor that takes no arguments. If a class does not explicitly define any constructor, the Java compiler automatically provides a no-argument default constructor to initialize object members to their default values (e.g., 0, null, or false).

A Parameterized Constructor is a constructor that accepts one or more arguments. It is used to provide different values to distinct objects at the time of their creation, allowing for custom initialization of instance variables.

There are three primary ways to read input from the console in Java:

1. Scanner Class: Part of the java.util package, this is the most common and easiest way to read primitive types and strings using regular expressions. It provides methods like nextInt(), nextDouble(), and nextLine().
2. BufferedReader Class: Found in the java.io package, this is used with an InputStreamReader. It reads data as a stream of characters and is generally faster than Scanner because it buffers the input, though it requires manual parsing of data types.
3. Console Class: Introduced in Java 6, the java.io.Console class is specifically designed for console-based applications. It provides methods like readLine() and readPassword(), the latter of which allows for secure input by not echoing characters to the screen.