Java Questions

Q:

What is a ResultSet ?

Answer

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.

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0 2184
Q:

What is local class?

Answer

Local class is class defined inside method


EX;


class A { // top level class


  public static void main(string[] args) {


   class B { // local class


   }


}


}

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Subject: Java

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Q:

How to call argument constructor?

Answer

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);


    }


}

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Subject: Java

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Q:

What is the difference between path and classpath?

Answer

Path contains path of .exe files(commands).


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

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Q:

What is the purpose of the wait(), notify(), and notifyAll() methods ?

Answer

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..

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Q:

How to create Directory on the HD?

Answer

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

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Subject: Java

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Q:

What is the Set interface ?

Answer

- 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

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Q:

What is the similarity between Dynamic Binding and linking?

Answer

Dynamic binding is orthogonal to dynamic linking. Binding refers to the linking of a procedure call to the code to be executed in response to the call. Dynamic binding It is associated with polymorphism and inheritance, it(also known as late binding) means that the code associated with a given procedure call is not known until the time of the call at run-time.

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