Java beans are special type of POJOs.

Specialities listed below with reason

In summary: similarities and differences are:

   java beans:                          Pojo:
-must extends serializable              -no need to extends or implement.
 or externalizable.                     
-must have public class .               - must have public class
-must have private instance variables.      -can have any access specifier variables.
-must have public setter and getter method. - may or may not have setter or getter method.
-must have no-arg constructor.           - can have constructor with agruments.

All JAVA Beans are POJO but not all POJOs are JAVA Beans.

You've seen the formal definitions above, for all they are worth.

But don't get too hung up on definitions. Let's just look more at the sense of things here.

JavaBeans are used in Enterprise Java applications, where users frequently access data and/or application code remotely, i.e. from a server (via web or private network) via a network. The data involved must therefore be streamed in serial format into or out of the users' computers - hence the need for Java EE objects to implement the interface Serializable. This much of a JavaBean's nature is no different to Java SE application objects whose data is read in from, or written out to, a file system. Using Java classes reliably over a network from a range of user machine/OS combinations also demands the adoption of conventions for their handling. Hence the requirement for implementing these classes as public, with private attributes, a no-argument constructor and standardised getters and setters.

Java EE applications will also use classes other than those that were implemented as JavaBeans. These could be used in processing input data or organizing output data but will not be used for objects transferred over a network. Hence the above considerations need not be applied to them bar that the be valid as Java objects. These latter classes are referred to as POJOs - Plain Old Java Objects.

All in all, you could see Java Beans as just Java objects adapted for use over a network.

There's an awful lot of hype - and no small amount of humbug - in the software world since 1995.

All Pojo(s) are JavaBean(s), but not the opposite.

What is POJO?

1. A POJO has no naming convention for properties or methods. We don't follow any real convention for constructing, accessing, modifying the class's state.

   Example:

    public class Pojo {
   
     public String firstname;
     public String LASTName;
   
     public String name() {
        return this.firstname + " " + this.LASTName;
     }
    }
   

   here, I could have replaced firstname by first_name or Firstname or by any noun and the same with the variable LASTName.

The term has most likely gained widespread acceptance because of the need for a common and easily understood term that contrasts with complicated object frameworks.[2]

Reflection using POJO.

it may limit a framework's ability to favor convention over configuration, understand how to use the class, and augment its functionality.[1]

  List<String> propertyNames =
                Arrays.stream(PropertyUtils.getPropertyDescriptors(Pojo.class))
                        .map(PropertyDescriptor::getDisplayName)
                        .collect(Collectors.toList());
        System.out.println(propertyNames);

If we use Third Party Libraries PropertyUtils for reflection we may face issues, as this will result in

[]

What is Java Beans?

A JavaBean is still a POJO but introduces a strict set of rules around how we implement it:

• Access levels – our properties are private and we expose getters and setters.
  
• Method names – our getters and setters follow the getX and setX convention (in the case of a boolean, isX can be used for a getter)
  
• Default Constructor – a no-argument constructor must be present so an instance can be created without providing arguments, for example during deserialization
  
• Serializable – implementing the Serializable interface allows us to store the state.

Example:

@Getter
@Setter
 class Pojo implements Serializable {
    public String firstName;
    public String lastName;
}

Reflection using Java Bean.

[firstName,lastName]