Course

Introduction

Print an Integer (Entered by the User)Add Two Integers Multiply two Floating Point Numbers Find ASCII Value of a character Compute Quotient and Remainder Swap Two Numbers Check Whether a Number is Even or Odd Check Whether an Alphabet is Vowel or Consonant Find the Largest Among Three Numbers Find all Roots of a Quadratic Equation Find the Frequency of Character in a String Remove All Whitespaces from a String Round a Number to n Decimal Places Check if a String is Empty or Null

Type Conversion

Convert Character to String and Vice-Versa convert char type variables to int convert int type variables to char convert long type variables into int convert int type variables to long convert boolean variables into string convert string type variables into boolean convert string type variables into int convert int type variables to String convert int type variables to double convert double type variables to int convert string variables to double convert double type variables to string convert primitive types to objects and vice versa

Functions

Display Prime Numbers Between Intervals Using Function Display Armstrong Numbers Between Intervals Using Function Check Whether a Number can be Expressed as Sum of Two Prime Numbers Find the Sum of Natural Numbers using Recursion Find Factorial of a Number Using Recursion Find G.C.D Using Recursion Convert Binary Number to Decimal and vice-versa Convert Octal Number to Decimal and vice-versa Convert Binary Number to Octal and vice-versa Reverse a Sentence Using Recursion calculate the power using recursion Call One Constructor from another implement private constructors pass lambda expression as a method argument Pass the Result of One Method Call to Another Method Calculate the Execution Time of Methods

Arrays

Calculate Average Using Arrays Find Largest Element of an Array Calculate Standard Deviation Add Two Matrix Using Multi-dimensional Arrays Multiply Two Matrix Using Multi-dimensional Arrays Multiply two Matrices by Passing Matrix to a Function Find Transpose of a Matrix Print an Array Concatenate Two Arrays Check if An Array Contains a Given Value

Object and Class

Add Two Complex Numbers by Passing Class to a Function Calculate Difference Between Two Time Periods Determine the class of an object Create an enum class Print object of a class Create custom exception Create an Immutable Class

String

Convert String to Date Convert a Stack Trace to a String Compare Strings Check if a String is Numeric Check if two strings are anagram Compute all the permutations of the string Create random strings Clear the StringBuffer Capitalize the first character of each word in a String Iterate through each characters of the string.Differentiate String == operator and equals() method Implement switch statement on strings Check if a string contains a substring Check if a string is a valid shuffle of two distinct strings

Collections

Join Two Lists Convert a List to Array and Vice Versa Convert Map (HashMap) to List Convert Array to Set (HashSet) and Vice-Versa Sort a Map By Values Sort ArrayList of Custom Objects By Property Implement LinkedList Implement stack data structure Implement the queue data structure Get the middle element of LinkedList in a single iteration Convert the LinkedList into an Array and vice versa Convert the ArrayList into a string and vice versa Iterate over an ArrayList Iterate over a HashMap Iterate over a Set Merge two lists Update value of HashMap using key Remove duplicate elements from ArrayList Get key from HashMap using the value Detect loop in a LinkedList Calculate union of two sets Calculate the intersection of two sets Calculate the difference between two sets Check if a set is the subset of another set Sort map by keys Pass ArrayList as the function argument Iterate over ArrayList using Lambda Expression Implement Binary Tree Data Structure Perform the preorder tree traversal Perform the postorder tree traversal Perform the inorder tree traversal Count number of leaf nodes in a tree Implement the graph data structure Remove elements from the LinkedList.Add elements to a LinkedList Access elements from a LinkedList.

Algorithms

Implement Bubble Sort algorithm Implement Quick Sort Algorithm Implement Merge Sort Algorithm Implement Binary Search Algorithm

Files

Get Current Working Directory Create String from Contents of a File Append Text to an Existing File Convert File to byte array and Vice-Versa Create File and Write to the File Read the Content of a File Line by Line Delete File in Java Delete Empty and Non-empty Directory Get the File Extension Get the name of the file from the absolute path Get the relative path from two absolute paths Count number of lines present in the file

I/O Stream

Convert InputStream to String Convert OutputStream to String Convert a String into the InputStream Convert the InputStream into Byte Array Load File as InputStream

Advanced

Get Current Date/Time Convert Milliseconds to Minutes and Seconds Add Two Dates Convert Byte Array to Hexadecimal Lookup enum by String value Calculate simple interest and compound interest Implement multiple inheritance Determine the name and version of the operating system Check if two of three boolean variables are true Iterate over enum Check the birthday and print Happy Birthday message Access private members of a class

Java Program to Determine the class of an object

To understand this example, you should have the knowledge of the following Java programming topics:

Example 1: Check the class of an object using getClass()


              
class Test1 {
// first class
}

class Test2 {
// second class
}

class Main {
  public static void main(String[] args) {
    // create objects
    Test1 obj1 = new Test1();
    Test2 obj2 = new Test2();

    // get the class of the object obj1
    System.out.print("The class of obj1 is: ");
    System.out.println(obj1.getClass());

    // get the class of the object obj2
    System.out.print("The class of obj2 is: ");
    System.out.println(obj2.getClass());
  }
}

Output


              
The class of obj1 is: class Test1
The class of obj2 is: class Test2

In the above example, we have used the getClass() method of the Object class to get the class name of the objects obj1 and obj2.

To learn more, visit Java Object getClass().

Example 2: Check the class of an object using instanceOf operator


              
class Test {
// class
}

class Main {
  public static void main(String[] args) {
    // create an object
    Test obj = new Test();

    // check if obj is an object of Test
    if(obj instanceof Test) {
      System.out.println("obj is an object of the Test class");
    }
    else {
      System.out.println("obj is not an object of the Test class");
    }
  }
}

Output


              
obj is an object of the Test class

In the above example, we have used the instanceof operator to check if the object obj is an instance of the class Test.

Example 3: Check the class of an object using isInstance()


              
class Test {
// first class
}

class Main {
  public static void main(String[] args) {
    // create an object
    Test obj = new Test();

    // check if obj is an object of Test1
    if(Test.class.isInstance(obj)){
      System.out.println("obj is an object of the Test class");
    }
    else {
      System.out.println("obj is not an object of the Test class");
    }
  }
}

Output


              
obj is an object of the Test class

Here, we have used the isInstance() method of the class Class to check if the object obj is an object of the class Test.

The isInstance() method works similarly to the instanceof operator. However, it is preferred during the run time.