Home Java

Instance initializer block

The instance data member is initialized using the Instance Initializer block. Every time an object belonging to the class is created, it runs.
Although the instance variable can be initialized directly, additional operations may be carried out as part of the initialization process in the instance initializer block.

Rules for instance initializer block

Instance initializer block is created,When a class instance is created.
After calling the parent class constructor, or after calling super(), the instance initializer block is called.
They appear in the order that they do in the instance initializer block.

Example of instance initializer block

Java example of instance initializer block

 // Java example of instance initializer block

class Car{ 
	int Speed ;
	Car(){  
	 System.out.println("Max speed of Car : "+Speed);  
	} 
	{Speed=140;}  //initialize variable
}    
class Main{
	public static void main(String args[]){  
		Car car=new Car();   
	}  
}

Output:

Max speed of Car : 140

Instance initializer block with constructor

Java example of instance initializer block with constructor

 // Java example of instance initializer block with constructor

class Main{   
    Main(){
    	System.out.println("constructor ");
    }   
    {System.out.println("Instance initializer block");}  
       
    public static void main(String args[]){  
    	Main b1=new Main();  
    	Main b2=new Main();  
    }      
}

Output:

Instance initializer block

constructor

Instance initializer block

constructor

The Java compiler copies the instance initializer block code into each constructor.

Learn more about java super keyword Next »

Another Example of instance initializer block

Java example of instance initializer block

 // Java example of instance initializer block

class A{  
	A(){  
	 System.out.println("parent class constructor");  
	}  
}    
class B extends A{  
	B(){  
	 super();  
	 System.out.println("child class constructor");  
	}
	{System.out.println("instance initializer block");}  
}

class Main{
	public static void main(String args[]){  
		B b=new B();   
	}  
}

Output:

parent class constructor

child class constructor

Instance initializer block

Java instanceof Next »

« Perv Next »

Instance initializer block

Rules for instance initializer block

Example of instance initializer block

Java example of instance initializer block

Instance initializer block with constructor

Java example of instance initializer block with constructor

Another Example of instance initializer block

Java example of instance initializer block

Post your comment

Useful Links

Contact Us

About DockerTpoint