java - Can we create a non parameterized constructor in servlet? -

what know till now:

• instance of servlet first created container via reflection , no argument constructor gets used.
• then parameterized init method gets called.

also suggested should not create constructor in servlet class of no use. , agree that.

lets say, have created no argument constructor in servlet class , within calling parameterized constructor. question is, called container?

public class demoservlet extends httpservlet{      public demoservlet() {       this(1);    }    public demoservlet(int someparam) {       //do parameter    } } 

will demoservlet() called container , if put initializing stuff inside it, executed? guess yes it's guess based on understanding.

this might pretty useless, asking out of curiosity.

you correct guess. demoservlet() called container , initialization code within executed - if initialization done through constructor-chaining , matter of fact way have dependency injection , create thread-safe servlet testable typically written way

public class demoservlet extends httpservlet {    private final someparam; //someparam final once set cannot changed     //default constructor called runtime.    public demoservlet()    {        //constructor-chained paramaterized constructor        this(1);    }     //observe paramaterized constructor has   //package-level visibility. useful being invoked through   //  unit , functional tests typically reside within same    //package. allow test code inject required values   //verify behavior while testing.    demoservlet(int someparam)    {       this.param = param    }     //... other class code... }