Java Questions

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

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.

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 use an iterator to traverse through the contents of a collection, follow these steps:

- Obtain an iterator to the start of the collection by calling the collections iterator() method.

- Set up a loop that makes a call to hasNext(). Have the loop iterate as long as hasNext() returns true.

- Within the loop, obtain each element by calling next().

Java applications can call code written in C, C++, or assembler. This is sometimes done for performance and sometimes to access the underlying host operating system or GUI API using the JNI.

The steps for doing that are:

First write the Java code and compile it

Then create a C header file

Create C stubs file

Write the C code

Create shared code library (or DLL)

Run application

- The Set interface provides methods for accessing the elements of a finite mathematical set

- Sets do not allow duplicate elements

- Contains no methods other than those inherited from Collection

- It adds the restriction that duplicate elements are prohibited

- Two Set objects are equal if they contain the same elements

Local class is class defined inside method

EX;

class A { // top level class

  public static void main(string[] args) {

   class B { // local class

   }

}

}