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Java Interview Questions on Collection - 13 Questions

Question: 1

Find the output of below program

import java.util.*; 

public class Main
{
	public static void main(String[] args) {
	    List<Integer> mylist = new ArrayList();
	    System.out.println(mylist.size());
	}
}

(A) Compilation Error
(B) Exception
(C) 1
(D) 0

[Posted by: Admin | Location: Chicago, USA]

Question: 2

import java.util.*; 

public class Main
{
	public static void main(String[] args) {
	    List<Integer> mylist = new ArrayList();
	    mylist.remove(0);
	    System.out.println(mylist.size());
	}
}

(A) Nothing is printed
(B) IndexOutOfBoundsException
(C) Compilation Error
(D) 0

[Posted by: Admin | Location: Chicago, USA]

Question: 3

Find the output of below program

import java.util.*; 

public class Main
{
	public static void main(String[] args) {
	    List<Integer> mylist = new ArrayList();
	    mylist.add(5);
	    System.out.println(mylist.remove(0));
	}
}

(A) Nothing is printed
(B) Compilation Error
(C) Exception
(D) 5

[Posted by: Admin | Location: Chicago, USA]

Question: 4

Find the output of below program

import java.util.*; 

public class Main
{
	public static void main(String[] args) {
	    List<Integer> mylist = new ArrayList();
	    System.out.println(mylist.add(5));
	}
}

(A) Nothing is printed
(B) 5
(C) 0
(D) true

[Posted by: Admin | Location: Chicago, USA]

Question: 5

import java.util.*; 

public class Main
{
	public static void main(String[] args) {
	    List<Integer> mylist = new ArrayList();
	    mylist.add(-2);
	    mylist.add(-1);
	    mylist.add(0);
	    int a = mylist.get(-1);
	    System.out.println(a);
	}
}

(A) -1
(B) 0
(C) IndexOutOfBoundsException
(D) None of the above

[Posted by: Admin | Location: Chicago, USA]

Question: 6

Find the output of below program

import java.util.*; 

public class Main
{
	public static void main(String[] args) {
	    List<Integer> mylist = new ArrayList();
	    mylist.add(-2);
	    mylist.add(-1);
	    mylist.add(0);
	    System.out.println(mylist.get((mylist.remove(2))));
	}
}

(A) true
(B) -2
(C) Compilation Error
(D) 0

[Posted by: Admin | Location: Chicago, USA]

Question: 7

Find the output of below program

import java.util.*; 

public class Main
{
	public static void main(String[] args) {
	    List<Integer> mylist = new ArrayList();
	    mylist.add(-2);
	    mylist.add(-1);
	    mylist.add(0);
	    
	    System.out.print(mylist.size());
	    for(int i = 0; i<mylist.size(); i++){
	        mylist.remove(i);
	        System.out.print(mylist.size());
	    }
	    
	}
}

(A) 331
(B) 3321
(C) 310
(D) 321

[Posted by: Admin | Location: Chicago, USA]

Question: 8

List is part of Java Collections API

(A) True
(B) False

[Posted by: Admin | Location: Chicago, USA]

Question: 9

Find the output of below program

import java.util.*;

public class Main
{
public static void main(String[] args) {
    List<Integer> list = new ArrayList();
    list.add(10);
    System.out.print(list.size());
    List<Integer> list2 = new ArrayList(list);
    System.out.print(list2.size());

    }
}

(A) 22
(B) 12
(C) 11
(D) 21

[Posted by: Admin | Location: Chicago, USA]

Question: 10

Java List has an instance variable to handle the size.
It is incremented when you add, and decremented when you remove. Calling list.size() returns a variable, and is therefore O(1)

(A) True
(B) False

[Posted by: Admin | Location: Chicago, USA]

Question: 11

What is Big-O complexity notation to search an element in List

(A) O(1)
(B) O(n)
(C) O(log(n))
(D) None of these

[Posted by: Admin | Location: Chicago, USA]

Question: 12

What is Big-O complexity notation to insert an element in List

(A) O(n)
(B) O(1)
(C) O(log(n))
(D) None of these

[Posted by: Admin | Location: Chicago, USA]

Question: 13

Which collection framework allows null values and is unsynchronized?

(A) HashTable
(B) EnumSet
(C) Vector
(D) ArrayList

[Posted by: Admin | Location: Chicago, USA]

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