Because it is not a regular Java Class that is executed by a JVM. It is a special Java class that is executed by the Web Container which initializes and loads the servlet and the service methods get executed everytime it receives a request.
Constructor is used to do something (written in constructor) immediately after object creation.
Constructor is necessary when you are about to use instance of a class.
When we are initializing our object with different internal state then we can use the constructor overloading.
A JavaBean is nothing but a regular Java Class and hence it can be instantiated using the new keyword and invoking the bean constructor
default constructor is used only when the programmer does not use a constructor to initialize objects. Once the programmer defines a constructor then the default constructor is no longer used
You are free to override the default constructor whenever you like. In fact, if you want to keep the default constructor when you also need a parameterized constructor, you have to override the default constructor in order to use it. Once you've written the parameterized constructor, the default constructor goes away.
A Private constructor is simply a constructor that can only be used within the class it was declared in. By default java creates you a constructor which is public though. Hope that helps
A constructor is simply a function that is called when a new object is created.
Java Servlet is used for Server Side programming for developing Web Applications. It easily employs Database Connectivity. We can also use JSP however it cannot replace a Java Servlet.
Http servlet and Generic servlet
to create an instance of object