There are four different ways to create objects in java:
- Using new keyword
- Using Class.forName():
- Using clone():
- Using Object Deserialization:
- Using newIntance() method
Using new keyword:
This is the most common way to create an object in java. Almost 99% of objects are created in this way.
MyObject object=new Object();
Using Class.forName():
- If we know the name of the class & if it has a public default constructor we can create an object in this way.
- Syntax:
- Myobject obj=(MyObject) class.forName("object").newInstance();
Using clone():
- The clone() can be used to create a copy of an existing object.
- Syntax:
- MyObject obj=new MyObject();
- MyObject object=(MyObject )obj.clone();
Using Object Deserialization:
- Object deserialization is nothing but creating an object from its serialized form.
- Syntax:
- objectInputStream istream=new objectInputStream(some data);
- MyObject object=(MyObject) instream.readObject();
Using newInstance() method
Object obj = DemoClass.class.getClassLoader().loadClass("DemoClass").newInstance();
Java Program on creating object using new keyword:
package com.instanceofjava;
public class Employee
{
private int id;
private String name;
Employee(int id,String name){
this.id=id;
this.name=name;
}
public void display(){
System.out.println(id+" "+name);
}
public static void main (String args[]){
Emploee e=new Employee(1,"Indhu");
Employee e1=new Employee(2,"Sindhu");
e.display();
e1.display();
}
}
Output:
Indhu
Sindhu
Java Program on creating object using clone() method:
package com.instanceofjava;
public class Empcloneable implements Cloneable {
int a;
String name;
Empcloneable(int a,String name){
this.a=a;
this.name=name;
}
public Empcloneable clone() throws CloneNotSupportedException{
return (Empcloneable) super.clone();
}
public static void main(String[] args) {
Empcloneable e=new Empcloneable(2,"Indhu");
System.out.println(e.name);
try {
Empcloneable b=e.clone();
System.out.println(b.name);
} catch (CloneNotSupportedException e1) {
e1.printStackTrace();
}
}
}
Output:
Indhu
Indhu
Java Program on creating object using Deserialization
package com.instanceofjava;
import java.io.*;
public class Files
{
public static void main(String [] args)
{
Employee e = null;
try
{
FileInputStream fileIn = new FileInputStream("/E/employee.txt");
ObjectInputStream in = new ObjectInputStream(fileIn);
e = (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("Name: " + e.name);
}
}
Output:
Name:Indhu
Java Program on creating object using class.forName();
package com.instanceofjava;
public class Sample{
public static void main(String args[]){
try {
Class s= Class.forName("com.instanceofjava.Sample");
Sample obj=(Sample) s.newInstance();
System.out.println(obj.hashcode());
} catch (Exception e) {
e.printStackTrace();
}
}
}
Output:
2007759836
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