Interfaces and Abstract Classes -Java Programming MCQ Questions and Answers

import java.io.*;
class filesinputoutput 
{
    public static void main(String args[]) 
    {
        InputStream obj = new FileInputStream("inputoutput.java");
        System.out.print(obj.available());
    }
}

interface calculate
{
    void cal(int item);
}
class displayA implements calculate
{
    int x;
    public void cal(int item)
    {
        x = item * item;            
    }
}
class displayB implements calculate
{
    int x;
    public void cal(int item)
    {
        x = item / item;            
    }
}
class interfaces 
{
    public static void main(String args[])
    {
        displayA arr1 = new displayA;
        displayB arr2 = new displayB;
        arr1.x = 0;
        arr2.x = 0;      
        arr1.cal(2);
        arr2.cal(2);
        System.out.print(arr1.x + " " + arr2.x);
    }
}

import java.io.*;
class files 
{
    public static void main(String args[]) 
    {
        File obj = new File("/java/system");
        System.out.print(obj.getParent());
        System.out.print(" " + obj.isFile());
    }
}

class Output
{
    public static void main(String args[])
    {
        Double y = new Double(257.57812);
  Double i = new Double(257.578123456789);  
        try
        {
      int x = i.compareTo(y);
            System.out.print(x);
        }
        catch(ClassCastException e)
        {
            System.out.print("Exception");
        }
}
}

public class BoxDemo
{
    public static <U> void addBox(U u, java.util.List<Box<U>> boxes)
    {
       Box<U> box = new Box<>();
       box.set(u);
       boxes.add(box);
    }
    public static <U> void outputBoxes(java.util.List<Box<U>> boxes)
    {
        int counter = 0;
        for (Box<U> box: boxes)
        {
            U boxContents = box.get();
            System.out.println("Box #" + counter + " contains [" + boxContents.toString() + "]");
            counter++;
        }
    }
    public static void main(String[] args)
    {
        java.util.ArrayList<Box<Integer>> listOfIntegerBoxes = new java.util.ArrayList<>();
        BoxDemo.<Integer>addBox(Integer.valueOf(10), listOfIntegerBoxes);
        BoxDemo.outputBoxes(listOfIntegerBoxes);
    }
}

import java.util.*;
class LOCALE_CLASS
{
    public static void main(String args[])
    {
        Locale obj = new Locale("HINDI", "INDIA") ;
        System.out.print(obj.getCountry());
    }
}