Entity: In general entity is an object that has some distinct value. In a persistent storage mechanism, an entity is a business object. Each entity has an associated table in relational database. Each instance of the entity represents a row of the table.

Entity class is an annotated POJO (Plain Old java Object). Here are some points to be noted during writing entity class:

· Class must have constructor

· Create getter setter for each field

· Don?t define any field static or final.

Example:

Here is an entity class named Employee.java.It mapped the employee table.

package net.roseindia.table;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import java.util.Date;

@Entity
@Table(name = "employee")
public class Employee {
    @Id
    @GeneratedValue
    @Column(name = "emp_id")
    private int id;

    @Column(name = "name")
    private String name;

    @Column(name = "salary")
    private int salary;

    @Column(name = "date_of_join")
    private Date dateOfJoin;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getSalary() {
        return salary;
    }

    public void setSalary(int salary) {
        this.salary = salary;
    }

    public Date getDateOfJoin() {
        return dateOfJoin;
    }

    public void setDateOfJoin(Date dateOfJoin) {
        this.dateOfJoin = dateOfJoin;
    }

}