Part 3
Interview questions on Collections in java for experienced covered in this post:
Can you explain internal working of ArrayList?
-
When you create an object of ArrayList default size of the
ArrayList is 10.
-
Means the initial size of the ArrayList is 10.
-
When the ArrayList gets to fill 75% then internally JVM
performs many operations.
-
Internally JVM creates a new ArrayList, Copy all the elements
of the old ArrayList into the new ArrayList.
-
New ArrayList object size will be calculated by this
formula.
1.
New Size = ((Current Size * 3 ) / 2) + 1.
-
Old ArrayList objects will be eligible for garbage
collection.
-
Reference variable points to the new ArrayList object.
-
Every time JVM performs the same process when an object gets
full of 75%.
- Please refer below image to better understanding.
What is LinkedList?
-
Basically, LinkedList is a type of data structure that can be
used to save the data and address of the next node.
-
LinkedList is an implementation of the List interface.
-
Linkedlist has three types.
1.
Singly LinkedList.
2.
Doubly LinkedList.
3.
Ciruclar LinkedList.
-
Please refer to the below example.
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package simplifiedjava.crackedInterview; import java.util.LinkedList; class SinglyLinkedList { public static void main(String[] args) {
LinkedList<Integer> linkedList
= new
LinkedList<Integer>();
linkedList.add(50);
linkedList.add(100);
linkedList.add(150);
linkedList.add(200); linkedList.add(250);
for(Integer i
: linkedList) {
System.out.println(i);
}
}
} |
- Graphically representation of linked list.
 
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What are the characteristics of LinkedList?
-
Insertion order preserved.
-
Duplicates objects are allowed.
-
Heterogeneous (Different types of Object) objects are
allowed.
-
The NULL insertion is possible.
-
LinkedList is Clonable because LinkedList implements a
Clonable interface.
-
LinkedList is Serializable because LinkedList implements a
Serializable interface.
-
LinkedList is the worst choice if want to perform a serach or
sort operation.
-
LinkedList has not implemented RandomAccess.
What is Vector? What are the characteristics of Vector?
-
A vector can be defined as a dynamic array that can grow or
shrink on its own.
-
Vector will grow when more elements are added to it and will
shrink when elements are removed from it.
-
But similar to arrays, vector elements can be accessed using
integer indices.
-
Default size of vector is 10.
-
Vector is a legacy class.
- Please refer to the below example.
|
package simplifiedjava.crackedInterview;
import
java.util.Iterator; import java.util.Vector; public class VectorDemo {
public
static
void
main(String[] args) {
Vector<Integer> v
= new
Vector<Integer>();
v.add(10);
v.addElement(20);
v.add(30); v.addElement(40);
// Using foreach.
for(Integer i
: v) {
System.out.println(i);
}
// Using iterator
Iterator<Integer> itr
= v.iterator();
while(itr.hasNext()) {
Integer i
= itr.next();
System.out.println("Value of Vector "+ i);
}
}
} |
What are the characteristics of Vector?
-
Resizable / Growable array.
-
Insertion order preserved.
-
Duplicated objects are allowed.
-
Heterogeneous (Different types of Object) objects are
allowed.
-
The NULL insertion is allowed.
-
Vector is thread-safe.
-
Vector is Serializable because LinkedList implements a
Serializable interface.
-
Vector is the worst choice if want to perform serach or sort
operation.
-
Vector has implemented RandomAccess.
What is the initial capacity of Vector?
-
Vectors initial capacity is 10.
What is Stack and what are the characteristics of Stack?
-
Stack is a linear data structure.
-
Stacks works with LIFO (Last In First Out).
-
Stack is a child class of Vector.
-
Real-Life example: We have observed many times in the
cafeteria, Waiter always picks the top of the plate to serve the food to
each customer.
Which collection classes implements RandomAccess interface? What are the benefits of RandomAccess interface?
-
ArrayList and Vector are implemented Random Access
Interface.
-
The presence of a marker interface is that it indicates ( or
expects ) specific behaviour from the implementing class.
-
So, in our case, ArrayList implements the RandomAccess marker
interface.
-
So, the expectation from the ArrayList class, is that it
should produce RandomAccess behaviour to the clients of the ArrayList class
when the client wants to access some element at some index.
Which scenario are the best example to implement of LinkedList and ArrayList?
-
LinkedList: If
you want to perform addition and deletion kind of operation in between the
list then we should go for LinkedList.
-
ArrayList: If
you want to perform a searching, sorting kind of operation then we should go
for ArrayList.
Which Collection objects implements Queue interface?
-
LinkedList implements Queue interface.
-
Java interview questions and answers all MNC - Click here
-
Basic core java interview questions and answers for freshers
- Click here
-
Core java interview questions for 3 years experience - Click here
-
Core java interview questions and answers for 3-5 years exp
- Click here
-
Core java interview questions and Answers for 5 - 7 Years exp
- Click here
-
Basic Java Interview Questions and Answers - Click here
-
Java interview questions and answers on oops - Click here
-
Java interview questions and answers on Strings - Click here
-
Java interview questions on exception handling - Click here
-
Interview questions on multithreading in java for experienced
- Click here
-
Interview questions on serialization in java for experienced
- Click here
-
Interview questions on inner class in java for experienced
- Click here
-
Interview questions on Collections in java for experienced
- Click here
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