Java ArrayList

Here are 10 essential multiple-choice questions on Java ArrayList, covering key concepts.

Last Updated : Apr 1, 2025

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Question 1

What is the default initial capacity of an ArrayList when it is created using the no-arg constructor?

A
5
B
10
C
20
D
1

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Question 2

What will be the output of the following code?

Java

import java.util.*;
public class Test {
    public static void main(String[] args) {
        ArrayList<Integer> list = new ArrayList<>();
        list.add(1);
        list.add(2);
        list.add(3);
        list.remove(1);
        System.out.println(list);
    }
}

A
[1, 3]
B
[2, 3]
C
[1, 2]
D
[1, 2, 3]

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Question 3

Which method of ArrayList is used to add an element at a specific index?

A
addAtIndex()
B
insert()
C
add()
D
add(index, element)

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Question 4

What will be the result of the following code?

Java

import java.util.*;
public class Test {
    public static void main(String[] args) {
        ArrayList<Integer> list = new ArrayList<>();
        list.add(10);
        list.add(20);
        list.add(30);
        list.add(40);
        list.set(2, 50);
        System.out.println(list);
    }
}

A
[10, 20, 50, 40]
B
[10, 20, 30, 40]
C
[10, 20, 40, 50]
D
[50, 20, 30, 40]

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Question 5

Which of the following methods is used to check if an ArrayList is empty?

A
isEmptyList()
B
isNull()
C
isEmpty()
D
empty()

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Question 6

What will be the output of the following code?

Java

import java.util.*;
public class Test {
    public static void main(String[] args) {
        ArrayList<String> list = new ArrayList<>();
        list.add("Apple");
        list.add("Banana");
        list.add("Cherry");
        list.add("Date");
        list.remove("Banana");
        System.out.println(list);
    }
}

A
[Apple, Cherry, Date]
B
[Apple, Banana, Cherry, Date]
C
[Banana, Apple, Cherry, Date]
D
[Apple, Cherry, Date, Banana]

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Question 7

Which of the following methods returns the number of elements in an ArrayList?

A
size()
B
length()
C
count()
D
getSize()

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Question 8

What will happen if you try to access an element with an index greater than the size of the ArrayList?

A
It throws an ArrayIndexOutOfBoundsException
B
It throws a NoSuchElementException
C
It returns null
D
It throws an IndexOutOfBoundsException

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Question 9

What is the time complexity of the add() method in an ArrayList (amortized case)?

A
O(1)
B
O(n)
C
O(log n)
D
O(n^2)

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Question 10

What is the maximum capacity of an ArrayList?

A
1000 elements
B
The maximum value of an integer
C
2^31 - 1 elements
D
There is no maximum capacity

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