Java Questions

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

Path contains path of .exe files(commands).

Classpath contains path of packages. packages can be stored in folder or .jar files

boolean isDirectory();

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

new ClassName( arg1, arg2, .... argN);

Ex:

Class sample {

   Sample(int a) {

   System.out.println("arg con a =" +a);

   }

}

class Demo {

    Public static void main( String[] args) {

     Sample s1= new Sample(23);

     Sample s2= new Sample(45);

    }

}

JDBC technology is an API (included in both J2SE and J2EE releases) that provides cross-DBMS connectivity to a wide range of SQL databases and access to other tabular data sources, such as spreadsheets or flat files. With a JDBC technology-enabled driver, you can connect all corporate data even in a heterogeneous environment.

Two types of classes:

1) Top Level Class

2) Classes within Class

       i) member classes

             a) static member class

             b) non static member class

      ii) local classes

      iii) anonymous classes

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