Java Questions

To do multi threading in java we use interfaces and classes defined in java.lang package.

Those classes and interfaces are:

Java.lang.Runnable, Java.lang. Thread, Java.lang.ThreadGroup

To create directory on the HD we use mkDir() method:

boolean mkDir();

This method returns true if the directory is created on HD

This method returns false if the directory is already existing on HD

- By using method overriding a sub class can change the definition of super class method.

- By using overriding a sub class can modify the functionality of the super class.

DriverManager is a class in java.sql package. It is the basic service for managing a set of JDBC drivers.

If constructor opens the file 

finalize() method closes that file.

If constructor opens the connection 

finalize() method closes that connection.

To perform finalization operation we must overriding finalize method.

SimpleTimeZone is a concrete subclass of TimeZone class. The TimeZone class represents a time zone, that is to be used with Gregorian calendar.

The SimpleTimeZone is created by using the base time zone offset from GMT time zone ID and rules, for starting and ending the time of daylight.

A static initializer block is a block of code that declares with the static keyword. It normally contains the block of code that must execute at the time of class loading. The static initializer block will execute only once at the time of loading the class only.

By using super call we can call super class constructors  from sub class constructors and we can initialize super class private data.