Anonymous object in Java

An object which has no reference variable is called anonymous object in Java. Anonymous means nameless.  If you want to create only one object in a class then the anonymous object is a good approach.

Declaration of Anonymous object

The syntax to create an anonymous object in Java is given below.
Syntax:

new Class_name();

For example:
         new Student();

We can pass the parameter to the constructor like this:
         new Student(“Shubh”);

If you want to call a method through the anonymous object then you can write code like this:
        new Student().display();

We can also pass the parameter to the calling method like this:
        new Student().display(“Shubh”, 25);


Let’s create a program where we will implement all these concepts in a program.
Program source code 1:

package anonymousObject; 
 public class Multiplication 
 { 
// Declare the instance variables.
     int a; 
     int b; 
     int c; 
     int d; 
// Declare the parameterize constructor and initialize the parameters. 
     Multiplication(int p, int q)
     { 
       a = p; 
       b = q; 
       int ab = a * b; 

       System.out.println("Multiplication of a and b:" +ab); 
      } 
// Declare an instance method and initialize parameters. 
     void multiply(int x, int y )
     { 
       c = x; 
       d = y; 
       int cd = c * d; 
       System.out.println("Multiplication of c and d:" +cd); 
     } 
public static void main(String[] args) 
 { 
// Create the anonymous object and pass the values to the constructor and calling method. 
      new Multiplication(25,25).multiply(10, 20); 

// We can also pass the different values with the same anonymous object. // but we cannot create another new anonymous object. 
      new Multiplication(20,20).multiply(30, 30); 
    } 
 }

 

Output: 
       Multiplication of a and b: 625 
       Multiplication of c and d: 200 
       Multiplication of a and b: 400 
       Multiplication of c and d: 900

Let’s make another program where we will create an anonymous object and calculate area and perimeter of square by passing different values to constructor and method.

Program source code 2:

package anonymousObject; 
 public class Calculation 
 { 
// Declare instance variable. 
     int a; 

// Declaration of one parameter constructor. 
     Calculation(int p)
     { 
      a = p; 
     } 
// Declaration of instance methods. 
    void area()
    { 
      int area = a * a; 
      System.out.println("Area of square: " +area); 
    } 
void perimeter(int b)
{ 
   int peri = 4 * b; 
   System.out.println("Perimeter of square: " +peri); 
 } 
public static void main(String[] args)
 { 
// Create anonymous object. 
     new Calculation(50).area(); 
     new Calculation(10).perimeter(100); 
     new Calculation(20).area(); 
     new Calculation(30).perimeter(200); 
  } 
}
Output: 
       Area of square: 2500 
       Perimeter of square: 400 
       Area of square: 400 
       Perimeter of square: 800

Hope that this tutorial has covered all important points related to anonymous object. Remember the following points related to Java anonymous object.

Learn by Heart
1. A class that does not have name is called anonymous class in Java.
2. An object that does not have reference variable is called anonymous object.
Thanks for reading!!!
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