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5 ways to create an object in java

As we know that creation of an object in java is a cost-effective affair. Therefore we should have knowledge of different ways to create Objects in java so that we can use a particular way in the given scenario to handle the situation in a better way. Here we will find out 5 ways to create an object in Java.

Using new keyword :

This way of creating object in Java is the most common way in all.

Object obj= new Object();

Using newInstance() method of class ‘Class’ :

You must be aware of the Reflection API in Java. However, under reflection API we have these classes ‘Class’ & ‘Constructor’. Moreover, both classes have newInstance() method in it to create objects in Java. Therefore, we will see newInstance() method of class ‘Class’ in this section:

Class c=Class.forName("com.dev.SampleClass");  
  SampleClass s=(SampleClass)c.newInstance();  

           OR  

SampleClass sc=SampleClass.class.newInstance();

Using newInstance() method of class ‘java.lang.reflect.Constructor’:

Class.newInstance() can only invoke the zero-argument constructor, while Constructor.newInstance() may invoke any constructor, regardless of the number of parameters.

Constructor<Test> ctor = Test.class.getDeclaredConstructor();
    ctor.setAccessible(true);
    Test test = (Test)ctor.newInstance();

Using clone() method of class java.lang.Object:

clone() method creates and returns a copy of this object. In order to use clone() method class should implement Cloneable interface then it should implement clone() method accordingly. In this case, constructor of the class will not be called.

public class Student implements Cloneable {
		String name;
		int rollno;

		Student(String name, int rollno) {
			this.name = name;
			this.rollno = rollno;
		}

		public Object clone() throws CloneNotSupportedException {
			return super.clone();
		}

		public static void main(String args[]) {
			try {
				Student s1 = new Student("Vicky",1234);

				Student s2 = (Student) s1.clone();

				System.out.println(s1.rollno + " " + s1.name);
				System.out.println(s2.rollno + " " + s2.name);

			} catch (CloneNotSupportedException c) {
			}

		}
	}

Using Deserialization :

The other way is to create an instance is by de-serializing the Object. We have to serialize the object before deserializing it as below:

public class Student implements Serializable {
		
		   public static void main(String[] args) throws Exception {
			   Student obj = new Student();
		      // serialization
		      FileOutputStream fos = new FileOutputStream("serialization.txt");
		      ObjectOutputStream oos = new ObjectOutputStream(fos);
		      oos.writeObject(obj);
		      // de-serialization
		      FileInputStream fis = new FileInputStream("serialization.txt");
		      ObjectInputStream ois = new ObjectInputStream(fis);
		      Student student = (Student)ois.readObject();
		      
		   }
		}	

However, we have seen 5 ways to create an object in Java. Furthermore, we have other ways like the one which is used by Spring Container for bean instantiation. Every java developer should know about creation of objects as we can’t stay tuned with java without knowing it. Additionally, we will extend the article if we find any other update in this topic. Please don’t hesitate to comment if you find any update on this topic.

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