Java Questions

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

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

boolean isDirectory();

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

Path contains path of .exe files(commands).

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

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);

    }

}

A table of data representing a database result set, which is usually generated by executing a statement that queries the database.

ResultSet object maintains a cursor pointing to its current row of data. Initially the cursor is positioned before the first row. The next method moves the cursor to the next row, and because it returns false when there are no more rows in the ResultSet object, it can be used in a while loop to iterate through the result set.

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