Java Programming Practice MCQs Codetantra. CBT-6

Java Programming Practice MCQs Codetantra. CBT-6

The topics to be included in that will be Files and IO Streams, Annotations & Assertions (L53-55), and Collections (L56-60) And PEV106 Practice MCQs

01 What will be the output of the following code snippet?

 	Map <Integer, String> map= new HashMap<>();
	map.put(5, "Amit");
	map.put(3, "Naveen");	
	map.put(2, "Amit");	
	map.put(5, "Rajan");	
	map.put(null, "Sanchit");
	System.out.println(map.get(null) + " " + map.get(5));

Sanchit Amit
Sanchit Rajan
NullPointerException
Compilation Error: Incompatible types

02. Suppose e:\Unit4 and d:\Java\ABC.txt exists but

e:\Unit4\CBT6.txt does not exist.

What will happen when the following program is compiled and executed?

import java.nio.file.*;
import java.io.*;

class Demo
{
  public static void main(String [] arg) throws Exception
  {
	Path p1 = Paths.get("d:\\Java\\ABC.txt");	 
	Path p2 = Paths.get(e:\\Unit4\\CBT6.txt);     
	Files.copy(p1, p2);
  }
}

CBT6.txt will be created inside e:\Unit4 directory but
d:\Java\ABC.txt will not be removed
CBT6.txt will be created inside e:\Unit4 directory and
d:\Java\ABC.txt will be removed
Code will not compile
NoSuchFileException will occur

03. Suppose e:\Unit4 and d:\Java\ABC.txt exists but

e:\Unit4\CBT6.txt does not exist.

What will happen when the following program is compiled and executed?

import java.nio.file.*;
import java.io.*;

class Demo
{
  public static void main(String [] arg) throws Exception
  {
	Path p1 = Paths.get("d:\\Java\\ABC.txt");	 
	Path p2 = Paths.get(e:\\Unit4\\CBT6.txt);     
	Files.move(p1, p2);
  }
}

CBT6.txt will be created inside e:\Unit4 directory and
d:\Java\ABC.txt will be removed
CBT6.txt will be created inside e:\Unit4 directory but
d:\Java\ABC.txt will not be removed
Code will not compile
NoSuchFileException will occur

04. What will be the output of the following code snippet?

 	HashMap <Integer, String> map= new TreeMap<>();
	map.put(5, "Amit ");
	map.put(3, "Naveen ");	
	map.put(2, "Amit ");	
	map.put(3, "Rajan ");	
	map.put(5, "Sanchit "); 
	Collection <String> val = map.values();
	System.out.println(val);

[Amit, Naveen, Rajan, Sanchit]
[Amit, Naveen, Sanchit]
Compilation Error
[Amit, Rajan, Sanchit]

05. What will be the output of the following code snippet?

	Comparator <Integer> c = (x, y) -> {
			if(x > y) return 1;
			else return -1;
			     };
 	Set <Integer> set= new TreeSet<>(c);
	set.add(5);
	set.add(3);
	set.add(4);
	set.add(2);
	set.add(3);
	System.out.println(set);

[5, 4, 3, 3, 2]
[5, 4, 3, 2]
[2, 3, 4, 5]
[2, 3, 3, 4, 5]

06. Which of the following statement is TRUE about the following program?

import java.io.*;

class Demo
{
  public static void main(String [] arg) 
  {
     try(FileInputStream fin = new FileInputStream("d:\\Java\\abc.txt");
	FileOutputStream fout = new FileOutputStream("result.txt"))
       {
	byte b = fin.read();  //Line 1
	fout.write(b);      //Line 2
       }	
     catch(IOException ex) { System.out.println(ex); }
  }
}

Compilation Error in Line 1
Compilation Error in Line 2
abc.txt and result.txt files must exist to execute the program successfully.
It will throw FileNotFoundException is result.txt is not present.

07. Which of the following statement is TRUE about the following program?

import java.nio.file.*;
import java.io.*;

class Demo
{
  public static void main(String [] arg) throws Exception
  {
	Path p1 = Paths.get("d:\\Java\\ABC.txt");	     
	Files.delete(p1);
  }
}

NoSuchFileException will be thrown if ABC.txt file does not exist.
FileNotFoundException will be thrown if ABC.txt file does not exist.
DirectoryNotEmptyException will be thrown if the directory d:\Java is not empty.
None of These

08. What will be the output of the following code snippet?

	ArrayList <Integer> al = new ArrayList<>();
	al.add(5);   al.add(2);
 	Set <Integer> set= new TreeSet<>((a, b) -> a > b ? 1 : -1 );
	set.add(5);
	set.add(3);
	set.add(5);
	set.remove(2);
	set.addAll(al);
	System.out.println(set);

[2, 3, 5]
[5, 3, 2]
None of These
[3, 5]

09. What will be the output of the following code snippet?

 	Map <Integer, String> map= new TreeMap<>();
	map.put(5, "Amit ");
	map.put(3, "Naveen ");	
	map.put(2, "Amit ");	
	map.put(3, "Rajan ");	
	map.put(5, "Sanchit "); 
	Collection <String> val = map.values();
	System.out.println(val);

[Amit, Naveen, Rajan, Sanchit]
[Amit, Naveen, Sanchit]
Compilation Error
[Amit, Rajan, Sanchit]

10. What will be the output of the following code snippet?

	ArrayList <Integer> al = new ArrayList<>();
	al.add(5);  al.add(2);
 	Set <Integer> set= new LinkedHashSet<>();
	set.add(5);
	set.add(3);
	set.add(5);
	set.remove(2);
	set.addAll(al);
	System.out.println(set);

[2, 3, 5]
[5, 3, 2]
None of These
[3, 5]

11. Predict the output of below given code snippet:

import java.io.*;
import java.util.*;
class Main {	
	public static void main(String[] args) {
		ArrayList<Integer> arrayList = new ArrayList<Integer>();
			arrayList.add(48);
		    arrayList.add(80);
			arrayList.add(112);
	    	arrayList.remove(1);
		    System.out.println(arrayList);
		    System.out.print(arrayList.get(2));
	}
}

[48, 112]
Exception in thread "main" java.lang.IndexOutOfBoundsException
[48, 112]
80
[80, 112]
80
error: cannot find symbol System.out.print(arrayList.get(1));
[80, 112]
112

12. Which of the following statement is TRUE about the following program?

import java.io.*;

class Demo
{
  public static void main(String [] arg) 
  {
     byte b = 65;
     try(FileOutputStream fout = new FileOutputStream("d:\\Java\\abc.txt", true))
       {
	fout.write(b);
       }	
     catch(IOException ex) { System.out.println(ex); }
  }
}

It will append "A" in the file abc.txt if it is already existing.
It will overwrite the content of abc.txt with "A" if abc.txt is already existing.
Compilation Error
It will throw FileNotFoundException is abc.txt is not present.

13. Suppose e:\Unit4 and d:\Java\ABC.txt exists but

e:\Unit4\CBT6.txt does not exist.

What will happen when the following program is compiled and executed?

import java.nio.file.*;
import java.io.*;

class Demo
{
  public static void main(String [] arg) throws Exception
  {
	Path p1 = Paths.get("d:\\Java\\ABC.txt");	 
	Path p2 = Paths.get(e:\\Unit4\\CBT6.txt);     
	Files.copy(p2, p1);
  }
}

NoSuchFileException will occur
CBT6.txt will be created inside e:\Unit4 directory and
d:\Java\ABC.txt will be removed
Code will not compile
CBT6.txt will be created inside e:\Unit4 directory but
d:\Java\ABC.txt will not be removed

14. Which of the following statement is TRUE about the following program?

import java.io.*;

class Demo
{
  public static void main(String [] arg) 
  {
     byte b = 65;
     try
       {
	FileOutputStream fout = new FileOutputStream("d:\\Java\\abc.txt", true);
	fout.write(b);
       }	
     catch(FileNotFoundException ex) { System.out.println(ex); }
  }
}

Compilation Error: Unreported Exception
It will always create a new file abc.txt and "A" will be written on that file.
It will append "A" in the file abc.txt if it is already existing.
It will throw FileNotFoundException is abc.txt is not present.

15. Which of the following statement is TRUE about the following program?

import java.nio.file.*;
import java.io.*;

class Demo
{
  public static void main(String [] arg) throws Exception
  {
	Path p1 = Paths.get("d:\\Java\\ABC");	     
	Files.delete(p1);
  }
}

DirectoryNotEmptyException will be thrown if the directory d:\Java\ABC is not empty.
NoSuchDirectoryException will be thrown if ABC directory does not exist.
None of These
FileNotFoundException will be thrown if ABC does not exist.

16. What will be the output of the following code snippet?

	List <Integer> al = new ArrayList<>();
	al.add(5);
	al.add(7);
	al.add(4);
	al.add(1, 4);
	al.set(4, 9);
	al.remove(2);
	System.out.println(al);

[4, 7, 9]
[5, 7, 9]
IndexOutOfBoundsException
[5, 4, 9]

17. Which of the following statement is TRUE about the following program?

import java.io.*;

class Student implements Serializable { }
class PartTimeStudent extends Student { }

class Demo
{
  public static void main(String [] arg) 
  {
     try(ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("students.txt")))
       {
	out.writeObject(new PartTimeStudent());  //Line 1
	out.writeObject(new Student());         //Line 2
       }	
     catch(IOException ex) { System.out.println(ex); }
  }
}

Objects of PartTimeStudent and Student both will be written in the file students.txt.
It will throw NotSerializableException because PartTimeStudent is not Serializable.
Compilation Error in Line 2
Compilation Error in Line 1

18. What will be the output of the following code snippet?

 	Map <Integer, String> map= new LinkedHashMap<>();
	map.put(5, "Amit ");
	map.put(3, "Naveen ");	
	map.put(2, "Amit ");	
	map.put(3, "Rajan ");	
	map.put(5, "Sanchit "); 
	Set<Integer> keys = map.keySet();
	for(Integer k: keys)
	System.out.print(map.get(k) + " ");

Amit Rajan Sanchit
Sanchit Rajan Amit
Compilation Error
Amit Rajan Sanchit

19.What will be the output of the following code snippet?

 	Map <Integer, String> map= new HashMap<>();
	map.put(5, "Amit ");
	map.put(3, "Naveen ");	
	System.out.print(map.put(2, "Amit "));	
	System.out.print(map.put(3, "Rajan "));	
	System.out.print(map.put(5, "Sanchit "));

nullNaveen Amit
Naveen Amit
None of These
Amit Rajan Sanchit

20.What will be the output of the following code snippet?

	Comparator <Integer> c = (x, y) -> {
			if(x < y) return 1;
			else return -1;
			   };
 	Set <Integer> set= new TreeSet<>(c);
	set.add(5);
	set.add(3);
	set.add(4);
	set.add(2);
	set.add(3);
	System.out.println(set);

[5, 4, 3, 3, 2]
[5, 4, 3, 2]
[2, 3, 4, 5]
[2, 3, 3, 4, 5]

21.What will be the output of the following code snippet?

	ArrayList <Integer> al = new ArrayList<>();
	al.add(5);
	al.add(7);
	al.add(4);
	al.add(1, 4);
	al.set(3, 9);
	al.remove(2);
	System.out.println(al);

[4, 7, 9]
[5, 7, 9]
IndexOutOfBoundsException
[5, 4, 9]

22.What will be the output of the following code snippet?

	List <Integer> al = new ArrayList<>();
	al.add(5);
	al.add(7);
	al.add(4);
	al.add(1, 4);
	al.set(2, 3);
	al.remove(3);
	System.out.println(al);

[4, 7, 3]
[5, 7, 4]
IndexOutOfBoundsException
[5, 4, 3]

23. Predict the output of below given code snippet:

import java.util.*;
public class Main {
	public static void main(String args[]) {
		HashMap<Integer, String> hash = new HashMap<Integer, String>();
		hash.put(-8, "1");
		hash.put(-8, "9");
	    hash.put(-8, "14");
		System.out.println(hash.get(-8));
		for (Map.Entry<Integer, String> iterator : hash.entrySet())
			System.out.println(iterator.getKey() + ":" + iterator.getValue());
	}
}

14
-8:14
1
9
14
-8:14
Compile time error
14
-8:1 9 14

24. Which of the following statement is TRUE about the following program?

import java.io.*;

class Demo
{
  public static void main(String [] arg) 
  {
     byte b = 65;
     try(FileOutputStream fout = new FileOutputStream("d:\\Java\\abc.txt", false))
       {
	fout.write(b);
       }	
     catch(IOException ex) { System.out.println(ex); }
  }
}

It will overwrite the content of abc.txt with "A" if abc.txt is already existing.
It will throw FileNotFoundException is abc.txt is not present.
Compilation Error
It will append "A" in the file abc.txt if it is already existing.

25. Predict the output of below given code snippet:

import java.io.*;
import java.util.*;
class Main {	
	public static void main(String[] args) {
		ArrayList<Integer> arrayList = new ArrayList<Integer>();
			arrayList.add(43);
		    arrayList.add(75);
			arrayList.add(107);
	    	arrayList.remove(1);
		    System.out.println(arrayList);
		    System.out.print(arrayList.get(1));
	}
}

[43, 107]
107
[75, 107]
107
error: cannot find symbol System.out.print(arrayList.get(1));
[75, 107]
75

26.What will be the output of the following code snippet?

	List <Integer> al = new ArrayList<>();
	al.add(5);
	al.add(7);
	al.add(2);
	al.add(1, 4);
	al.add(2, 5);
	al.remove(2);
	System.out.println(al);

[5, 4, 7, 2]
[5, 4, 5, 7]
IndexOutOfBoundsException
[5, 5, 7, 2]

27. What will be the output of the following code snippet?

	ArrayList <Integer> al = new ArrayList<>();
	al.add(5);   
    al.add(2);
 	Set <Integer> set= new TreeSet<>();
	set.add(5);
	set.add(3);
	set.add(5);
	set.remove(2);
	set.addAll(al);
	System.out.println(set);

[2, 3, 5]
[5, 3, 2]
None of These
[3, 5]

28. What will be the output of the following code snippet?

	Set <Integer> set= new LinkedHashSet<>();
	set.add(5);
	set.add(3);
	set.add(5);
	set.add(2);
	set.remove(5);
	set.add(3);
	set.add(5);
	System.out.println(set);

[2, 3, 5]
[5, 3, 2]
[3, 2, 5]
[5, 2, 3]

29. What will happen when the following program is compiled and executed?

import java.nio.file.*;
import java.io.*;

class Demo
{
  public static void main(String [] arg) 
  {
	Path p1 = Paths.get("d:\\Java\\ABC.txt");	 
	Path p2 = Paths.get(e:\\Unit4\\CBT6.txt);     
	Files.move(p1, p2);
  }
}

Code will not compile
NoSuchFileException will occur
CBT6.txt will be created inside e:\Unit4 directory and
d:\Java\ABC.txt will be removed
CBT6.txt will be created inside e:\Unit4 directory but
d:\Java\ABC.txt will not be removed

30. Suppose d:\Java\ABC.txt exists but

e:\Unit4 does not exist.

What will happen when the following program is compiled and executed?

import java.nio.file.*;
import java.io.*;

class Demo
{
  public static void main(String [] arg) throws Exception
  {
	Path p1 = Paths.get("d:\\Java\\ABC.txt");	 
	Path p2 = Paths.get(e:\\Unit4\\CBT6.txt);     
	Files.move(p1, p2);
  }
}

NoSuchFileException will occur
CBT6.txt will be created inside e:\Unit4 directory and
d:\Java\ABC.txt will be removed
Code will not compile
CBT6.txt will be created inside e:\Unit4 directory but
d:\Java\ABC.txt will not be removed

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