Question

I have a doubt, following is the code for the bufferedwriter

BufferedWriter out = new BufferedWriter(new FileWriter(testcasename+".html"));

Constructor of BufferedWriter accepts only parameter of reference type ‘Writer’ abstract class, how does ‘filewriter‘ class is instantiated in the above code ?

Answer 1

Not sure what you mean.

But you did new FileWriter(path) which creates a FileWriter instance and FileWriter extends Writer which makes it perfectly valid.

Writer isn’t an interface but an abstract class that can be extended or subclassed etc.

Interfaces are implemented. And new creates an object and returns a pointer or reference to that object. The reference is passed by value into the BufferedWriter constructor (think of a constructor as a special method) which accepts a Writer object.

I really hope my explanation made it clear.