1 . Introduction
2 . Basics
Find the Smallest Element in an Array
Check Whether a Number is Prime or Not
Number of Vowels in a String
Length of the String
Reverse a Given String
Second Largest Element in an Array
Find Factorial of a Number
Remove Spaces From a String
Swap two numbers Without Using the Third Variable
Count Number of Digits in a Number
Find Nth Fibonacci Number
Toggle the Case of Every Character in the String
Calculate the Number of Times a Digit Appears in a Number
Separate 0's and 1's from an Array
Separate Even and Odd Numbers in an Array
Count the Number of Capital Letters in a String
Sum of Largest and Smallest Element in an Array
Find x Power n Using Recursion
Reverse an Array Without Using the reverse() Method
Check Whether a String is Palindrome or Not
Check Two Strings are Anagrams or not
Find the Index of the First and the Last Occurrence of an Element
3 . Intermediate
Find Unique Character in a String
Check Whether Given Number is Armstrong or Not
Minimum Characters to Make a String Palindrome
Find Missing Number in a Number Sequence
Print Repeated Elements in a String
4 . Advanced
Find Leaders in an Array
Check If A Given String Is A Palindrome
Count the Number of Words in a String Using HashMap
Check Whether a String is a Valid Email Address
Permutation of a String
Find Longest Palindromic Substring in a Given String
Combinations of List Elements Whose Sum Equals the Target Value
5 . Theory Questions
Java Virtual Machine(JVM)
Types of Memory Area Allocated by JVM
JIT Compiler
Exceptions in Java
Static and Non-Static Method
Final Variable, Method and Class
No Pointers in Java
Overloading the main() Method
JVM, JRE, JDK
Wrapper Class
Making a Constructor final
Difference Between an Interface and an Abstract Class
Java Functional Interface
Multiple Inheritance not Supported in Java
Difference Between "throw" and "throws"
Overriding Static Method
Overriding an Overloaded Method
Does a class Inherit Constructors of its Superclass?
Create Instances When Constructor is not Defined
main() Method in Java
equals() Method and == operator
Garbage Collection in Java
HashMap and Hashtable
Local Variable and Instance Variable
Heap Memory and Stack Memory
main() isn't Declared as static
String, StringBuilder, StringBuffer
Multithreading in Java
final, finalize and finally
Enums
System Class
Global Variables
Synchronized Methods or Blocks
Iterator and ListIterator
Polymorphism
6 . Java Coding Challenges