In this post, we will see how to read object from file in java. In last post, we have already seen how to write object to a file and created employee.ser , now in this post, we are going to read same file and retrieve back Employee object.
Java Serialization Tutorial:
- Serialization in javaJava
- Serialization interview questions and answers
- serialversionuid in java serialization
- externalizable in java
- Transient keyword in java
- Difference between Serializable and Externalizable in Java
Steos for reading object from file are:
Reading object from file using ObjectInputStream may be referred as Deserialization.
Lets take an example:
Create Employee.java same as last example in src->org.arpit.java2blog
Create Employee.java same as last example in src->org.arpit.java2blog
1.Employee.java
package org.arpit.java2blog;
import java.io.Serializable;
public class Employee implements Serializable{
private static final long serialVersionUID = 1L;
int employeeId;
String employeeName;
String department;
public int getEmployeeId() {
return employeeId;
}
public void setEmployeeId(int employeeId) {
this.employeeId = employeeId;
}
public String getEmployeeName() {
return employeeName;
}
public void setEmployeeName(String employeeName) {
this.employeeName = employeeName;
}
public String getDepartment() {
return department;
}
public void setDepartment(String department) {
this.department = department;
}
}
Create DeserializeMain.java in src->org.arpit.java2blog
2.DeserializeMain.java
package org.arpit.java2blog;
import java.io.IOException;
import java.io.ObjectInputStream;
public class DeserializeMain {
/**
* @author Arpit Mandliya
*/
public static void main(String[] args) {
Employee emp = null;
try
{
FileInputStream fileIn =new FileInputStream("employee.ser");
ObjectInputStream in = new ObjectInputStream(fileIn);
emp = (Employee) in.readObject();
in.close();
fileIn.close();
}catch(IOException i)
{
i.printStackTrace();
return;
}catch(ClassNotFoundException c)
{
System.out.println("Employee class not found");
c.printStackTrace();
return;
}
System.out.println("Deserialized Employee...");
System.out.println("Emp id: " + emp.getEmployeeId());
System.out.println("Name: " + emp.getEmployeeName());
System.out.println("Department: " + emp.getDepartment());
}
}
3.Run it:
When you run above DeserializeMain.java and you will get following output:
Deserialized Employee... Emp id: 101 Name: Arpit Department: CS
These are some simple steps to read object from file. If you want to go through some complex scenario you can go through Serialization in java
