Java Questions

Path contains path of .exe files(commands).

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

Constructor chaining is the process of calling one constructor from another constructor with respect to current object.

Within same class: It can be done using this() keyword for constructors in same class

From base class: by using super() keyword to call constructor from the base class.

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

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

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

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);

    }

}

abstract method is a method declared with abstract modifier but  with out body.

The wait(), notify(), and notifyAll() methods are used to provide an efficient way for threads to wait for a shared resource. When a thread executes an object's wait() method, it enters the waiting state. It only enters the ready state after another thread invokes the object's notify() or notifyAll() methods..