How to create a POJO

Question

Recently I ve started hearing about  POJOs   Plain Old Java Objects   I googled it  but still don t understand the concept well  Can anyone give me a clear description of a POJO   Consider a class  Person  with variables  id  name  address  salary  -- how would I create a POJO for this scenario  Is the code below a POJO   public class Person         variables     People people   new People        private int id      private String name      private String address      private int salary        public int getId             return id             public String getName             return name             public String getAddress             return address             public int getSalary             return salary             public void setId             this id   id             public void setName             this name   name             public void setAddress             this address   address             public void setSalary             this salary   salary

User · Answer

there are mainly three options are possible for mapping purpose

serialize
XML mapping
POJO mapping.(Plain Old Java Objects)

While using the pojo classes,it is easy for a developer to map with the database. POJO classes are created for database and at the same time value-objects classes are created with getter and setter methods that will easily hold the content.

So,for the purpose of mapping in between java with database, value-objects and POJO classes are implemented.

User · Answer

POJO -  POJO is a Java object not bound by any restriction other than those forced by the Java Language Specification   Properties of POJO   All properties must be public setter and getter methods    All instance variables should be private  Should not Extend prespecified classes  Should not Implement prespecified interfaces   Should not contain prespecified annotations   It may not have any argument constructors   Example of POJO  public class POJO        private String value       public String getValue              return value             public void setValue String value            this value   value

User · Answer

File-setting-plugins-Browse repositories Search RoboPOJOGenerator and install  Restart Android studio Open Project and right click on package select on Generate POJO from JSON Paste JSON in dialogbox and select option according your requirements Click on Generate button

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According to Martin Fowler     The term was coined while Rebecca Parsons  Josh MacKenzie and I were preparing for a talk at a conference in September 2000  In the talk  we were pointing out the many benefits of encoding business logic into regular java objects rather than using Entity Beans  We wondered why people were so against using regular objects in their systems and concluded that it was because simple objects lacked a fancy name  So we gave them one  and it   s caught on very nicely    Generally  a POJO is not bound to any restriction and any Java object can be called a POJO but there are some directions  A well-defined POJO should follow below directions    Each variable in a POJO should be declared as private  Default constructor should be overridden with public accessibility  Each variable should have its Setter-Getter method with public accessibility  Generally POJO should override equals    hashCode   and toString   methods of Object  but it s not mandatory   Overriding compare   method of Comparable interface used for sorting  Preferable but not mandatory     And according to Java Language Specification  a POJO should not have to   Extend pre-specified classes Implement pre-specified interfaces Contain pre-specified annotations   However  developers and frameworks describe a POJO still requires the use prespecified annotations to implement features like persistence  declarative transaction management etc  So the idea is that if the object was a POJO before any annotations were added would return to POJO status if the annotations are removed then it can still be considered a POJO      A JavaBean is a special kind of POJO that is Serializable  has a no-argument constructor  and allows access to properties using getter and setter methods that follow a simple naming convention    Read more on Plain Old Java Object  POJO  Explained

User · Answer

POJO class acts as a bean which is used to set and get the value   public class Data     private int id      private String deptname      private String date      private String name      private String mdate      private String mname       public int getId             return id             public void setId int id            this id   id             public String getDeptname             return deptname             public void setDeptname String deptname            this deptname   deptname             public String getDate             return date             public void setDate String date            this date   date             public String getName             return name             public void setName String name            this name   name             public String getMdate             return mdate             public void setMdate String mdate            this mdate   mdate             public String getMname             return mname             public void setMname String mname            this mname   mname

User · Answer

When you aren t doing anything to make your class particularly designed to work with a given framework  ORM  or other system that needs a special sort of class  you have a Plain Old Java Object  or POJO   Ironically  one of the reasons for coining the term is that people were avoiding them in cases where they were sensible and some people concluded that this was because they didn t have a fancy name  Ironic  because your question demonstrates that the approach worked   Compare the older POD  Plain Old Data  to mean a C   class that doesn t do anything a C struct couldn t do  more or less  non-virtual members that aren t destructors or trivial constructors don t stop it being considered POD   and the newer  and more directly comparable  POCO  Plain Old CLR Object  in  NET

User · Answer

A POJO is a Plain Old Java Object   From the wikipedia article I linked to      In computing software  POJO is an   acronym for Plain Old Java Object  The   name is used to emphasize that a given   object is an ordinary Java Object  not   a special object  and in particular   not an Enterprise JavaBean   Your class appears to already be a POJO

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A POJO is just a plain  old Java Bean with the restrictions removed   Java Beans must meet the following requirements     Default no-arg constructor Follow the Bean convention of getFoo  or isFoo for booleans  and setFoo methods for a mutable attribute named foo  leave off the setFoo if foo is immutable  Must implement java io Serializable   POJO does not mandate any of these   It s just what the name says  an object that compiles under JDK can be considered a Plain Old Java Object   No app server  no base classes  no interfaces required to use     The acronym POJO was a reaction against EJB 2 0  which required several interfaces  extended base classes  and lots of methods just to do simple things   Some people  Rod Johnson and Martin Fowler among them  rebelled against the complexity and sought a way to implement enterprise scale solutions without having to write EJBs   Martin Fowler coined a new acronym   Rod Johnson wrote  J2EE Without EJBs   wrote Spring  influenced EJB enough so version 3 1 looks a great deal like Spring and Hibernate  and got a sweet IPO from VMWare out of it   Here s an example that you can wrap your head around   public class MyFirstPojo       private String name       public static void main String    args               for  String arg   args                     MyFirstPojo pojo   new MyFirstPojo arg       Here s how you create a POJO           System out println pojo                        public MyFirstPojo String name                    this name   name             public String getName     return this name          public String toString     return this name

User · Answer

public class UserInfo           String LoginId          String Password          String FirstName          String LastName          String Email          String Mobile          String Address          String DOB           public String getLoginId                 return LoginId                     public void setLoginId String loginId                LoginId   loginId                     public String getPassword                 return Password                     public void setPassword String password                Password   password                     public String getFirstName                 return FirstName                     public void setFirstName String firstName                FirstName   firstName                     public String getLastName                 return LastName                     public void setLastName String lastName                LastName   lastName                     public String getEmail                 return Email                     public void setEmail String email                Email   email                     public String getMobile                 return Mobile                     public void setMobile String mobile                Mobile   mobile                     public String getAddress                 return Address                     public void setAddress String address                Address   address                     public String getDOB                 return DOB                     public void setDOB String DOB                this DOB   DOB

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import java io Serializable   public class Course implements Serializable        protected int courseId      protected String courseName      protected String courseType       public Course             courseName   new String            courseType   new String               public Course String courseName  String courseType            this courseName   courseName          this courseType   courseType             public Course int courseId  String courseName  String courseType            this courseId   courseId          this courseName   courseName          this courseType   courseType             public int getCourseId             return courseId             public void setCourseId int courseId            this courseId   courseId             public String getCourseName             return courseName             public void setCourseName String courseName            this courseName   courseName             public String getCourseType             return courseType             public void setCourseType String courseType            this courseType   courseType              Override     public int hashCode             return courseId              Override     public boolean equals Object obj            if  obj    null    obj instanceof Course                Course c    Course  obj              if  courseId    c courseId  amp  amp  courseName equals c courseName                       amp  amp  courseType equals c courseType                   return true                    return false              Override     public String toString             return  Course     courseId         courseName         courseType

[java] How to create a POJO?

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