Java new Keyword

The Java new keyword is used to create an instance of the class. In other words, it instantiates a class by allocating memory for a new object and returning a reference to that memory. We can also use the new keyword to create the array object.

Syntax

Points to remember

It is used to create the object.
It allocates the memory at runtime.
All objects occupy memory in the heap area.
It invokes the object constructor.
It requires a single, postfix argument to call the constructor

Examples of Java new Keyword

Example 1

Let's see a simple example to create an object using new keyword and invoking the method using the corresponding object reference.

public class NewExample1 {

	void display()
	{
		System.out.println("Invoking Method");
	}
	
	public static void main(String[] args) {
		NewExample1 obj=new NewExample1();
		obj.display();
	}
	
}

Output:

Invoking Method

Example 2

Let's see a simple example to create an object using new keyword and invoking the constructor using the corresponding object reference.

public class NewExample2 {

	NewExample2()
	{
		System.out.println("Invoking Constructor");
	}
	
	public static void main(String[] args) {
		NewExample2 obj=new NewExample2();
	
	}
	
}

Output:

Invoking Constructor

Example 3

Here, we create an object using new keyword and invoke the parameterized constructor.

public class NewExample3 {

	int a,b;
	NewExample3(int a,int b)
	{
		this.a=a;
		this.b=b;
	}
	
	void display()
	{
		System.out.println(a+b);
	}
	
	public static void main(String[] args) {
		NewExample3 obj=new NewExample3(10,20);
		obj.display();
	}
	
}

Output:

Example 4

Let's see an example to create an array object using the new keyword.

public class NewExample4 {

	static int arr[]=new int[3];
	
	
	public static void main(String[] args) {
		System.out.println("Array length: "+arr.length);
	}
	
}

Output:

Array length: 3

Example 5

Let's see an example to use new keywords in Java collections.

import java.util.*;

public class NewExample5 {

	public static void main(String[] args) {
		List obj=new ArrayList();
		obj.add("Java");
		obj.add("C++");
		obj.add("Python");
		System.out.println(obj);
	}
	
}

Output: